Anonymous1: No no no Tai, what are you doing here, don't put your dick inside your Little Sister's asshole, you must put your dick inside youe Little Sister's pussy, so that you can fill her little girl womb up with your hot seed so that she can become pregnant like she is supposed to, so be a good Big Brother & switch holes now.
Oh & as for you Kari, don't even try to fight it Kari, be a good Little Sister & just let your Big Brother impregnate you, then just accept that your life as it once was is onver & that now your faith is to be Tai's babymaking machine and nothing eles.
Anonymous6(1): @Anonymous: Not in all cultures and nations, just look at The Royal Family House of Habsburg, for example.
@Anonymous: Yes she is 8 years old & that is the age girls starts to become fertile & can become pregnant.
Anonymous7(2): @Anonymous: My guy, females don't just "become fertile". When girls start to have periods, thats when pregnancy cano course and that can be anywhere from 10-literally never. Some girls just aren't fertile and can't have children. And for all you know, Kari could be one of those people. Also, the while reason why Royal families were incestual was to keep the royalty in the family line, which still doesn't justify it as "a comepletely normal and ok thing to sexualize"
Anonymous9(2): @Anonymous: Not to mention that in Japan (Digimon is set in Odaiba, Tokyo) only consensual, adult incest is allowed. This doesn't look consensual nor are they adults.
Anonymous10(1): @Anonymous: Some girls becomes fertile when they start to have periods and for all you know, Kari could be one of those people who are now able to become pregnant. Also in the digital world Kari is referd to as Queen Kari & that is why she must now keep her royaly family line pure.
Anonymous13(2): @Anonymous: But is it canonically true that Kari is actually part of a Royal Family? No, it's a nickname -- that's like saying since Joker is called the "Clown prince of Crime" he's an actual prince, you cuck.
And if you're the type of person who wants an 8 year old impregnated so desperately you'll say "yeah well maybe she is fertile mate" you seem like you need mental help and to be stuck in a jail cell.
Anonymous14(2): @Anonymous: Stop trying to justify your pedophilic, incestual wants. We get it, you think the little 8 year old is sexy and should have babies which by the way is an extremely painful process, one she might pass away during birth. So unless necrophilia makes you horny too, hope you feel good.
Anonymous15(1): @Anonymous: It didn't seem like a nickname to the Numemon who made her their Queen. All i want is for young Tai to impregnate young Kari & that's all.
Anonymous16(1): @Anonymous: Dude i have seen some pictures of her her where she is talking way bigger stuff than a baby in her little pussy, don't worry she will be fine.
Anonymous18(2): @Anonymous: Is Tai a Numemon? No, I didn't think so, so the idea that "It's okay because technically she's a queen to a different species" is complete butllshit, mate.
And still, if you "want it" or not, it's illegal as fuck. Just saying.
Anonymous21(2): @Anonymous: And you say that as if I'm suddenly going to thrown myself to your feet and grovel forgiveness because "all I like is incest loli x shorta nothing else". Shove a cactus up your ass, buddy.
Anonymous22(1): @Anonymous: I don't keep pictures of awesome hentai, i only watch pictures of awesome hentai pictures. @Anonymous: Well duh we are on R34, are you new here or something.
Anonymous24(2): @Anonymous: I'm gonna just bulk reply because I'm tired of this.
First of all, you "watch" pictures? that's pretty damn advanced tbh. Secondly, no, I am not new but saying that there's pictures of her taking larger than a baby as evidence is stupid because it's NOT CANON. Just like how belly bulge images are anatomically incorrect because if that happened your intestines would be ruptured.
Third: Oh yummy yummy, the "why are you here retard xdxd". I'm here to masturbate and defend fictional little girls, dumbass. I wasn't jerking to an 8yo, unlike you. No no, my palette is refined :)
Do you really think that someone could take a dick this large? The human rectum can only stretch up to 8 inches which, while that is a lot, probably still wouldn't be enough to accommodate something like that. Not to mention, again, the whole belly bulge thing. Leon would be fucking dead if this happened. It's, as I said, anatomically incorrect. Kira can't "Take bigger than a baby" physically because she's just a fucking little human girl.
Anonymous26(1): @Anonymous: Aww is the little Anon24(2) tired do you need a nap? She lives in a world where she can fysicly go into the internet, travel to different world, be picked apart by Apocalypmon & then being put back together again with no problem, but who a baby is just too much, you need to stop drinking & smoking so hard. Well then i have never seen anything more wortheless, pointless & pathetic than a user who feels the need to defend fictional little girls on a place like this.
Anonymous29(2): @Anonymous: And I've never seen someone so worthless, pointless and pathetic to the point they wanna impregnate an 8yo then proceed to defend it like they're pedophilic Phoenix Wright. Also, "fysicly"? Aww, what's wrong, little baby? Can't even spell physically and gets so butt hurt when I say your weird little fetishes are nasty? Oh no, let me apologize so the big bad Anon 1 will spare me! I'm so horribly sorry, let me play you a sad song on the world's smallest violin.
Not to mention the fact you used "XD" unironically. What is it, 2013? I feel so sorry that something happened to you as a child to the point you think that an 8yo getting fucked is normal and attractive. I'm tired of dealing with your shit, mate. You're saying I'm taking this argument "up your ass xdxd" when you've been here trying to defend the fact you want to see an 8yo get impregnated by her brother. Eat my shit and perish, you sewer rat.
Anonymous30(2): @Anonymous: Also, like I said way earlier on, it doesn't look like she consented. She bound and gagged and looks uncomfortable, like she, you know, is getting raped. So sure, she can "fysicly" go into the internet and travel to another world and etc etc, but it doesn't justify her getting raped, which is a painful experience both physically and emotionally.
Anonymous31(2): @Anonymous: Let's just stop. Yeah, I think you're hella nasty. You care so much about what other people think, yatta yatta yatta. I'm genuinely tired of dealing with this. Just go back to jerking it to little girls. I don't fucking care anymore, just get away from me, you little shithead.
Anonymous32(1): @Anonymous: You know what, it would be hot to see a picture of Phoenix Wright impregnate Young Trucy Wright. He you are a Grammar Nazi also, figures. For a prude fag like you anything eles than Married Hetro sex is weird. I will forgive you my child but don't play the violin, i like the electric guitarr much better.
I am bringing 2013 back my baby. Who knew you hade the brain to be able to feel the emotion of being sorry for another. Then if you are so tired let me put a diaper on you so that you can take a nap. You can't deny that Loli X Shorta inbreeding is hot as fuck if you have a brain at all to think with. I must say no my DR has orded me to keep a strict non shit diet so i have to decline, but hey more for you am i right.
Anonymous33(2): @Anonymous:
Almost heaven, West Jamaica
True ridge mountains
Shining Minko River
All my friends there
Older than those ridge
Younger than the mountains
Blowin' like a breeze
Country roads take me home
To the place I belong
West Jamaica, my ol' momma
Take me home country roads
I heard her voice
In the mornin' hour she calls me
Said son you remind me of my home far away
And drivin' down the road I feel a sickness, I sure did
Oh yesterday, yesterday
All my memories, oh, gathered 'round her
My old lady stranger to blue water
Dark and dusty painted on the sky
Misty taste of moonshine
Tears gone from my eyes
Country roads take me home
To the place I belong
West Jamaica, my my momma
Won't you take me go home country roads
please just leave me the fuck alone. I wanna eat my subway™ in peace.
Anonymous34(2): @Anonymous: also I literally sent the link to a pic where Leon from re2 just got fucked by Mr. X so idk what you mean when you say I hate anything that isnt hetero married sex,,?
Anonymous35(1): @Anonymous: Consent doesn't exist in the digital world, there everyone is free game, besides she will get used to it & love it after a wheil.
@Anonymous: You first my little pal. that is because you are very mean & prude. Again if you feel so tierd let me put you in a diaper so that you can take a nap then. I am llready done jerking so i must wait 30 mins to recharge. Then good then you have become normal like the rest of us here. But i want to have sex with you cockface.
Anonymous39(2): Almost heaven, West Jamaica
True ridge mountains
Shining Minko River
All my friends there
Older than those ridge
Younger than the mountains
Blowin' like a breeze
Country roads take me home
To the place I belong
West Jamaica, my ol' momma
Take me home country roads
I heard her voice
In the mornin' hour she calls me
Said son you remind me of my home far away
And drivin' down the road I feel a sickness, I sure did
Oh yesterday, yesterday
All my memories, oh, gathered 'round her
My old lady stranger to blue water
Dark and dusty painted on the sky
Misty taste of moonshine
Tears gone from my eyes
Country roads take me home
To the place I belong
West Jamaica, my my momma
Won't you take me go home country roads
Anonymous47: First, I want to state for the record that I have been working with high power R.F. transmitters and countermeasures sets, radar, communications, deception repeaters and jammers since 1973, and am quite experienced with in-flight dynamics of VHF signal propagation from both low altitude and high altitude aircraft, both civilian and military. Now, the average person is not too familiar with voltage standing wave ratios, or effective radiated power, insertion or line losses, reflected power, antenna gain factors or for that matter antenna radiation patterns on aircraft, as I am. I have extensive experience in these matters and have the actual aviation experience in a wide variety of aircraft, with regard to everything from H.F. long haul communications to millimeter wave jamming or ECM systems, radar, and navigation equipment. For this discussion we are going to talk strictly about 130 MHz, not 2 MHz, not 17 GHz, and the beam pattern and directionality and effective ranges of these systems on both commercial and military aircraft, both below and above the 12,500 pound weight category.
For those of you who are unfamiliar with path loss nomographs for 130 MHz, I would like you to make it a point to study the diagram below. Notice that no assumption is made for effective radiated power, or system gain factors, and there is a reason for this.
Path Loss Nomograph
This diagram is shown to illustrate the fact that, contrary to assertions by JREF and Unexplained Mysteries bloggers, radio waves do not just "keep on propagating" outwards at their original radiated power levels, without being attenuated over distance. When the path losses and other factors exceed the transmitter power and effective radiated power, as well as minimum discernible signal sensitivity of the receiver system, on any radial from the aircraft, and any angle of incidence, there is no possible communication then. Does this mean that the signals just stop moving thru space? Absolutely not.
But what this does mean is that as the distance increases to a point whereupon the signal power level decays below any possibility of detection by even triple conversion receivers with very selective front end circuitry that have incredibly high (-148 dBm or thereabouts) minimum discernible signal capture capability (which ACARS does not, nominally have, at it’s fairly robust –107 dBm), then beyond that range, detection and demodulation by any terrestrial, high gain, very directional and perhaps non interferometry based receive system, is highly unlikely to happen.
In any case, radio signals do not keep on radiating outwards without attenuation occurring due to signal density issues resultant from the fact that the greater distance from a transmitter from any antenna, the power distribution in fixed space, by laws of physics, will diminish with distance. Due to the totally unpredictable nature of the antenna radiation patterns of VHF blade antennae used by ACARS, it is a false assertion to state that there are no limitations between the RGS stations and the aircraft transmitter antenna for COM3, usually used on most Boeing airplanes, circa 1980’s and onwards, for ACARS.
In any case, what I would like to start with is that the aircraft and the antenna jointly form the transmit and receive radiation pattern in ways that are radically different from these same antenna systems being mounted on flat ground planes that offer at the very least a 90 degree counterpoise to the plane wave or electrical field leaving the antenna. The reason I cite this is that for any isotropic or non-directional antenna system, which these are not, due to their shapes being swept to minimize aerodynamic drag factors and prevent ice pickup or vibration resonances, these antennae used on commercial and military aircraft for VHF COMMUNICATIONS are what are referred to as ‘blade’ antennae of the type used on most commercial aircraft, including B-757/B-767’s.
For such antennae, there are some considerations that apply to them due to their shorter than quarter wave physical radiating length offset from the aircraft’s very curved fuselage or empennage. This results in significantly higher V.S.W.R. or ‘reflected’ energy back to the transmitter and not into free space. In addition to this, the shorter physical radiating element length versus the curved fuselage will radically change the radiation pattern and add directivity to these antennae, typically along the fuselage plane, fore and aft, as well as pushing the radiation pattern upwards or away (assuming the antenna is top mounted) so that the beam shape is not cardioid in nature but scalloped and with significant major pattern lobes that tend to create significant null zones that effectively reduce radiated power in those areas to the sides or in the ‘X’ plane (horizontal) by several ‘dB’ of gain, while significantly favoring the fore and aft orientation along the fuselage.
In the ‘Y’ axis (Vertical), looking at the beam pattern, the field lobes from the antenna depart the skin of the aircraft and contour upwards, once again, assuming the antenna is top mounted, and conversely, ‘downwards’ if the antenna is belly mounted. To characterize the full radiation or beam pattern, it would appear heavily scalloped in the ‘X’ axis, and quite finger or balloon lobed in the ‘Y’ axis, (vertical) plane.
In effect, the antenna that was supposed to be fairly omni-directional now is quite directional both fore and aft and has markedly higher gain factors in those directions, as well as pushing the pattern upwards into free space at any number of angles less than 90 degrees off the horizontal. The resultant 3-dimensional plot begins to look like a twisted doggie balloon shape and no longer resembles a spherical omni-directional beam plot.
The reason I mention this is that this directivity is nothing that can be readily compensated for without exotic counterpoise shapes around the base of the antenna, or multiple ‘Yagi’ type of elements in other directions to flatten or change the beam pattern. To compensate for these exotic and quite scalloped and lobed patterns that become reality when these relatively inefficient due to shorter radiating element length antennae are joined to a curving cylindrical tube which airplane fuselages tend to be, relative to the radiated field. And I would like to state that though there is a great deal of reciprocity between TRANSMIT and RECEIVE patterns, they do not necessarily fully reciprocate or remain the same for both functions due to any number of factors we will not discuss herein.
Anonymous48(47): In any case, what I would like to start with is that the aircraft and the antenna jointly form the transmit and receive radiation pattern in ways that are radically different from these same antenna systems being mounted on flat ground planes that offer at the very least a 90 degree counterpoise to the plane wave or electrical field leaving the antenna. The reason I cite this is that for any isotropic or non-directional antenna system, which these are not, due to their shapes being swept to minimize aerodynamic drag factors and prevent ice pickup or vibration resonances, these antennae used on commercial and military aircraft for VHF COMMUNICATIONS are what are referred to as ‘blade’ antennae of the type used on most commercial aircraft, including B-757/B-767’s.
For such antennae, there are some considerations that apply to them due to their shorter than quarter wave physical radiating length offset from the aircraft’s very curved fuselage or empennage. This results in significantly higher V.S.W.R. or ‘reflected’ energy back to the transmitter and not into free space. In addition to this, the shorter physical radiating element length versus the curved fuselage will radically change the radiation pattern and add directivity to these antennae, typically along the fuselage plane, fore and aft, as well as pushing the radiation pattern upwards or away (assuming the antenna is top mounted) so that the beam shape is not cardioid in nature but scalloped and with significant major pattern lobes that tend to create significant null zones that effectively reduce radiated power in those areas to the sides or in the ‘X’ plane (horizontal) by several ‘dB’ of gain, while significantly favoring the fore and aft orientation along the fuselage.
In the ‘Y’ axis (Vertical), looking at the beam pattern, the field lobes from the antenna depart the skin of the aircraft and contour upwards, once again, assuming the antenna is top mounted, and conversely, ‘downwards’ if the antenna is belly mounted. To characterize the full radiation or beam pattern, it would appear heavily scalloped in the ‘X’ axis, and quite finger or balloon lobed in the ‘Y’ axis, (vertical) plane.
In effect, the antenna that was supposed to be fairly omni-directional now is quite directional both fore and aft and has markedly higher gain factors in those directions, as well as pushing the pattern upwards into free space at any number of angles less than 90 degrees off the horizontal. The resultant 3-dimensional plot begins to look like a twisted doggie balloon shape and no longer resembles a spherical omni-directional beam plot.
The reason I mention this is that this directivity is nothing that can be readily compensated for without exotic counterpoise shapes around the base of the antenna, or multiple ‘Yagi’ type of elements in other directions to flatten or change the beam pattern. To compensate for these exotic and quite scalloped and lobed patterns that become reality when these relatively inefficient due to shorter radiating element length antennae are joined to a curving cylindrical tube which airplane fuselages tend to be, relative to the radiated field. And I would like to state that though there is a great deal of reciprocity between TRANSMIT and RECEIVE patterns, they do not necessarily fully reciprocate or remain the same for both functions due to any number of factors we will not discuss herein.
In any case, what I have just described is the highly irregular and moderately unpredictable and undesirable directivity of an otherwise fairly omni-directional antenna system. It is important to note this because a 3 dBm power differential in any of these planes, radiation pattern wise, effectively is a half power addition or reduction, with significant null points deeper than this that occur quite naturally, rendering the pattern even more complex and difficult to factor using system loss calculations, without actually making measurements in every axis with the aircraft either raised up and outside of what is called ‘near field’ distances of the ground below the aircraft.
Simply put, real world antenna radiation pattern measurements are possible and actually done, but in most cases scaled models with scaled frequencies, are typically used on non full-sized models inside of anechoic chambers or OTS (outdoor test) areas.
By large, most aircraft manufacturers do not attempt to make these measurements but make assumptions about radiation patterns that are not necessarily founded in known factual testing data, as usually is derived by MILITARY aircraft certifications laboratories who have a much more vested interest in characterizing these radiation patterns to maximize system effectiveness and head off or prevent unwanted ‘dead zones’ around the fighter or bomber or jamming platform these antennae are mounted on.
On many tactical jamming aircraft, the blade antenna arrays are more or less in ‘Yagi’ configurations to give directional gain that the mission capability of the aircraft needs to make maximum effective use of a communications jammer mounted on the aircraft. This is, however, never done on commercial airliner or Part 23 aircraft, to minimize cost and reduce weight.
As we have now more or less just barely touched on the radiation pattern, we have not yet begun to talk about signal polarization issues, and why they go hand in hand with more fully understanding how a theoretical two-way path loss calculation and predicted range of a system can be quite off in comparison to real world or ‘true’ and valid path losses and system effective radiated power determination, or receive sensitivity calculations.
What I am getting here is that a perfect isotropic vertical radiator element that rises 90 degrees off of a ground plane, or is oriented in the pure ‘Y’ axis pointed straight up, effectively has a VERTICAL ELECTRICAL FIELD POLARIZATION OF THE SIGNAL. In lay-person’s terms, ‘polarity’ of the electrical field, ideally, should be the same on both the transmit and receive end, to maximize signal transfer. In real life, this is difficult to achieve with swept blade antennae and curving aircraft fuselages which are the ground plane or ‘counterpoise’ for the antenna itself. The resultant polarization skewing hence causes a coupling factor inefficiency to occur, relative to the very polarization fixed antenna on the ground, intended to receive these signals.
IF the electrical field polarization shifts fully 90 degrees so it is not vertical at all but more ‘horizontal’ in relation to the very VERTICAL ground antennae respective polarity, the coupling mismatch is now at the very least ‘6’ dB less than optimal, of not more due to the curving fuselage, which is not a flat ground plane at all. Every ‘3’ dB is a half power loss when that number is a negative change. Why is this important?
Let’s theorize that from the transmitter rack, of the 50 watts transmitted off the jack in the rack itself, after ‘xx’ dB of loss in the transmission line, which in some cases is several meters in length, we are not going to see 50 watts of R.F. energy radiated into free space off of this antenna. Instead, if we are lucky, we’re more likely to see far less than 20 watts or thereabouts, leaving in all directions, not just going out in a single plane wave directly at the receive system on the ground, miles below. To better visualize this, imagine a light bulb on a lamp without a shade radiating light energy in all directions more or less evenly. Though light energy is significantly higher in frequency than is 130 Mhz. ACARS data link signal data, imagine the light bulb now has an array of fiber optics tubes radiating in all directions, affixed to the light bulb. In effect, the result is not anywhere near an omni-directional pattern at all, but a highly irregular, porcupine spoked shaped pattern of peaks and nulls radiating outwards, resulting in shadows in all directions on the walls of the room, and bright spots. This is more or less what the irregular radiation pattern of the ACARS blade antenna would look like if this were optical energy at a higher frequency. This analogy, as coarse as it may seem, is more or less descriptive of R.F. power density variations from a very spiked and valley ridden pattern radiating off the fuselage from the ACARS blade antenna, typically mounted on the aft belly of the fuselage on some Boeing aircraft, such as is the case with the B-737NG.
Anonymous49(47): Why is this important to understand, relative to the ACARS two-way range issue? Well, simply put, the moderately less than optimal V.S.W.R. of the antenna and transmission line and airplane fuselage now has reflected or ‘lost’ significant amounts of outbound R.F. energy that would have gone into free space in any number of ‘X’ and ‘Y’ and in fact, ‘Z’ plane directions from the radiating antenna or ‘blade’ on the fuselage. So we’re not dealing with our original 50 watts any longer, we are now pushing less than half of that into the free space around the airplane, in virtually all directions, in a very far from omni-directional radiation pattern, with deep peaks and nulls radiating outwards in all directions but overall favoring the fore and aft longitudinal axis of the aircraft. Translated, it means the myriad of ground stations around the aircraft will not be seeing anything close to the optimal range nomograph numbers at all, based on free space losses, as well as the very irregular antenna radiation pattern of the aircraft’s VHF blade antennas that are used by ACARS.
So now we are going to bring up the 200 mile claimed range number here. And the reason why, is that yes, in theory, due to the minimum discernible signal or sensitivity level of the ACARS receiver system of both the plane and the ground station is more or less known or can be approximated, what cannot be known is the coupling factor perturbations due to beam shaping and irregular radiation patterns that occur when blade antennas used in VHF communications are mounted on tubular aircraft fuselages. This results in significantly ‘lower’ than the expected or theoretical best 200 mile range supposition, by as much as 80 percent in real life.
Any experienced aviator who has used VOR navigation and who understands how the F.A.A. determined SERVICE VOLUME models for the each class of VOR facility, knows that even at FL-450, and above, a realm that few airliners routinely will fly at, by the way, due to cabin pressurization issues and aerodynamics, the effective range of the slightly lower in frequency of 108 to 118 Mhz., is reduced from that altitude to FL-600 or sixty thousand feet.
Why is this? Well, ground obstructions, and earth curvature now come into play here, as well as other similar signal degrading changes, and therefore the F.A.A.’s own data available to look at for these VOR facilities is less above FL-450. The F.A.A. didn’t arbitrarily pick these numbers out of some hat somewhere. They were derived by in-flight testing over literally all terrain types and at all altitudes, inclusive of FL-600 in some cases. The service volume diagrams from the F.A.A. website are relatively transferable to ACARS due to similarity of known and demonstrated effective ranges derived thru years of collective experience testing VOR reception service volumes, as well as R.C.O (remote communications outlet) communications ranges.
So we have more or less touched on irregular and highly unpredictable antenna radiation patterns in both the transmit and receive capability of 130 Mhz. communications and navigation systems in use today, and for all practical purposes really destroyed the rather inconsistent with real world performance, claims of ACARS working out to 200 nautical miles from any RGS station, due to these factors. In real life, no experienced line pilot could ever with a straight face claim that he’s tracked VOR’s at 200 nautical miles without flag tripping and sporadic reception, but also, it would be quite a stretch of the imagination to expect the performance for ACARS to routinely, every time, ever truly meet the outrageous claims of functionality at 200 miles from any aircraft, due to these factors cited here. Power output is not the determining factor here. Earth curvature is the predominant range limiter, as is terrain irregularity and obstructions around the ground station inside both ‘near field’ and ‘far field’ distances from the RGS stations.
As a commercially rated pilot with experience flying at virtually all of these altitudes up thru at least FL-350 in civil and military aircraft both as pilot and test engineer, I have to stipulate here that it is both ‘laughable’ and quite ‘uncommon’ to expect VOR reception much beyond 135 nautical miles even at the higher altitude regimes, and for that matter, to expect ACARS to work much further than these ranges over hilly and irregular terrain with mountains and ridges everywhere to throw a major ‘curve’ into any range calculation for these ACARS path losses.
Unfortunately many people who are claiming expertise in these areas are neither qualified to make these judgments due to a lack of R.F. engineering experience or real world testing experience and backgrounds, nor do they have any real world aircraft flight testing experience or flight experience using these systems in the real world. To assert that ACARS can communicate at 200 miles is not factual nor is it realistic. And it is wholly unfounded by any known factual testing data or practical experience of these outrageously optimistic ranges.
Furthermore, I’ll even go one step further here. If ANY experienced and non-anonymous airman with a valid pilot certificate at COMMERCIAL level and decades and thousands of hours of flight experience can validate VOR receptions beyond 150 miles under any circumstances, I would like to see their data and where this took place, in which aircraft, at what altitude. I do not expect many challenges to this more or less hard and fast rule here for VHF being pretty line-of-sight limited with very little effective terrain contouring or tropospheric ducting taking place. Any reasonably experienced line captain who has extensive ACARS experience in the Positive Controlled Airspace is welcome to controvert these claims with hard factual data.
In summary, the radiation patterns of real VHF communications blade antennas on heavy transport category aircraft, are both complex and highly unpredictable except to state that nominally there is some beam pattern lobing that prefers the longitudinal axis of the aircraft, to the fore and aft directions, while also shifting the electrical field far from optimal vertical polarization into any number of less optimal, and very inefficient signal polarizations that result in reduced ranges in most directions, and predictable and even more complex changes when these aircraft roll and bank in turns, further altering their radiation and reception patterns significantly from straight and level flight. Furthermore, as the aircraft’s crew is quite unaware this is in fact occurring, no action can be taken by either the crew of the aircraft’s system that can compensate for this. It is out of their hands entirely.
For the most part, it is unclear why some would surmise that ACARS should always be able to realistically and effectively work out to 200 nautical miles, and furthermore, that stations significantly closer to the aircraft would be totally unseen and not communicating under any circumstances, given what has been discussed here. Yes, the radiation pattern is lobed in all ‘3’ axis off of the aircraft, and yes this means the signal will follow the ground plane of the fuselage and wing structures somewhat, but to make the assertion that a station more than 100 nautical miles away would be favored over one that is less than 20 miles away, is not genuine nor credible.
We did not discuss a whole slew of other factors that adversely impact the effective ranges, such are atmospheric noise sources, co-channel interference, and things such as multi-path and reflections from both near the RGS station as well as the aircraft’s structures itself. Even something such as flap extension or landing gear deployment will significantly change the radiation patterns of most aircraft, whether the aircraft design or ARINC radio engineers like that or not.
Anonymous50(47): ACARS is not likely to work much further than 150 miles in most cases, under any and all circumstances, due to very extensive and recognized use of VOR changeover points on LOW ALTITUDE enroute IFR charts, showing that even at low altitudes up to and inclusive of FL-180, various enroute or Victor Airway reception ranges have been know for years and are published in both U.S. Government and Jeppesen/Sanderson IFR enroute charts and terminal charts for very very good reasons. These changeover points are the very best illustration of actual line-of-sight VHF communications ranges being adversely impacted by hilly terrain and other issues much more so than altitude, because if altitude above the ground were the sole arbiter of this, all changeover points for these low altitude airways or Victor Airways would be the same every single time, but they are not.
They are individual as hairs on your head. And so are the radial distances and ranges from any ACARS ground station using VHF line-of-sight frequencies. By necessity the technical assessment offered here is significantly less technical for a reason. You don’t need to be a pilot or a radio engineer to grasp most of these concepts explained within this moderately brief attempt to illustrate the point that several things are always going to be in play with radio ranges. Those are, to sum them up:
Radio signal strength decay over distance due to atmospheric attenuation and power density diminishment due to radial distances that dictate that with ‘X’ watts of energy radiated outwards from any radio source, that the power density window decreases on any given point far from the origin, even with highly directional and focused beams of radio energy.
Aircraft radiation patterns are not by their nature remotely close to omni-directional at all, even in the best cases such are transponder antennae at 1030 and 1090 Mhz, perhaps one of the shorter stub blades in use on any airplane, requiring far less ground plane uniformity to properly form an omni-directional radiation pattern.
Curvature of the earth and ground obstructions and line-of-sight VHF propagation characteristics are also significant range limiters at 130 MHz.
RGS stations an order of magnitude CLOSER to distant ones are far more likely to be the best LINE OF SIGHT paths under any and all but the most unusual cases where a mountain or a building between the RGS and the plane may in fact really make a much bigger attenuation factor between a closer station perhaps and a more distant one with a very clean, very direct, non-obstructed path, e.g.: if the more distant station is 100 or more miles away, it’s a real fantasy to state that one a mere 7 to 10 miles away, almost directly under the plane itself, would not be the preferred station, based on path losses alone, and virtually zero earth curvature to deal with there.
The one thing that most lay-persons do not experience in real flight regimes is loss of both communications signals and navigation signals, with something as simple as a small heading change. Something that typically is not a factor on most civilian air carrier aircraft but has been a major problem with general aviation airplanes, is antenna position due to other structures like landing gear, exhaust systems, and other small protuberances on the airplane that really skew the signal so much that it necessitates the pilot change course or heading to blindly fish around and find a better angle offset to allow both ATC to hear you, or for your transponder's signal to be seen by a distant radar station, because your exhaust system or landing gear (in some cases always down because it is not retractable) gets in the way and changes things.
High altitude planes don't typically drop gear and flaps, but they do have many other shape perturbations in both the near field and the far field regions of these antennae that make it unlikely that the aircrew is going to alter course or turn to better line up an antenna pattern 'lobe' so the ground can now see their signal and communicate.
After years of flying both fixed gear and retractable gear planes with all sorts of shapes, I have found that antenna radiation patterns are very very spooky and variable and are not published in any flight manual. But any pilot who knows about near field and far field interference and blocking of his signal would, like me, change course to try to get the signal reception needed for a little bit longer at the extreme outer effective ranges of radar, transponder, and communications / navigation equipment. Airline crews don't do this. But over three decades of flying, I have done it routinely to regain IFF to RADAR functionality, or DME functionality, and for that matter, even COMM/NAV functionality. In one case due to the location of a pair of GPS antennae on the skin of a plane, even GPS was affected somewhat, and it changed RAIM factor on approaches...due to the ground based WAAS augmentation being less optimal on some IFR approaches.
In any case if I find a good VHF radiation pattern plot to ship, I'll send it. But these patterns are very complex. Very very complex, and in real life, as airplane makers don't get real data about this, very highly unpredictable and way less than optimal per engineering calculations for them.
Addendum: The truth is that the transmission lines and, in fact, the essential grounding terminations on most airliners are degraded over time, which in fact increases the insertion losses between the antenna and the rack on the plane by (using signal generators and power meters) as much as 6 db more than normal. That's why ARINC specifically states "up to 200 nm" at FL 29 as maximum range. What happens in reality is that, due to overall crappy maintenance and corrosion on aircraft skins, with the bonding so questionable for the transmission line shield integrity at the antenna connector being so generally not optimal, it's a stretch to really get that 200 miles very often except with very new aircraft or exceptionally well maintained airplanes. Cyclical maintenance schedules do not even touch routine corrosion prevention on these antenna grounding plates unless the plane is removed from service and then completely overhauled. Bottom line: a range of 180 nm at best.
But now let's take a closer look at the quote that JREF people use to “prove” that VHF ACARS has a range of 250 nautical miles. The title of the document is “Signal-In-Space Minimum Aviation System Performance Standards (MASPS) For Advanced VHF Digital Data Communications Including Compatibility With Digital Voice Techniques”, and is available for download here. I will quote now the complete paragraph as it is (pp. 48–49):
The propagation characteristics of the VHF band restrict transmission and reception to essentially line-of-sight conditions. The maximum line of-sight range for an enroute aircraft at an altitude of 30,000 feet is about 250 nautical miles. The radio range decreases at lower altitudes to astrictly localized coverage when the aircraft is on the ground. The normal index of refraction of the atmosphere is greater than unity, which extends the possible range of VHF transmissions most of the time.
However, the refractivity varies widely, resulting in a significantly lower reliability of extended-range communications. The VHF radio channel is subject to slow and fast fading due to time varying multipath, obstruction of the radio line of sight, and changes in atmospheric conditions. The predominantly line-of-sight nature of VHF radio limits its use for air-ground and ground-air communications to airspace that can be served by land-based stations. Thus, coverage is limited to reasonably accessible over-land areas. Air-to-air communication is possible in any airspace, subject to the constraints of line-of-sight, transmitter effective radiated power, and receiver subsystem sensitivity.
The first part not marked in bold is the part that supporters of the official story of 9/11, selectively quote. The second part marked in bold is what he knowingly omitted. And why did he omit it? Because, if read in its entirety, the above paragraph clearly proves the contrary of what intended by the poster. While 250 nm is to be considered as the max. technical line of-sight range at an altitude of 30,000 ft, in reality ground-air communications are limited by physical constraints such as "transmitter effective radiated power, and receiver subsystem sensitivity". All this is clearly described in the document quoted, but obviously the poster removed this essential information from his original quote because the resulting meaning would be completely different than the intended. As a matter of fact, the document quoted by the guy completely confirms (one more time) why ARINC only guarantees deliveries "up to 200 nm", whereas "up to 200 nm" is to be interpreted in its simple, literal meaning and not as a distance that one can personally adapt based on circumstances or can fit into a theory that has been already and conclusively proven as wrong for many other reasons.
Finally, if the poster insists that the VHF range can jump up to 265 nm when an aircraft is flying at 35 FL using an online calculator as best evidence for this claim, then I inform him that United 93 dropped a DLBLK block containing "ORDA6" in the "BepStnName =" at 9:40 EDT, while the distance from the Chicago airport was 278.46 nm. Also, in the second DLBLK block within the same message there is a reference to IADC6. Dulles airport at 9:40 EDT was 238.05 nm from United 93!
Anyway, if the poster on UM is really confident about the theory he's claiming, then I challenge him to contact an ARINC professional and present it. I challenge him to prove that an aircraft could not see a station at only 7 miles at 9:35 EDT or two stations at only 20 miles at 9:40 EDT, but was able to see stations at 238.05 nm and 278.46 nm as "RGS with the strongest signal". Until then I will keep on thinking that his claim is completely unfounded.
Dennis Cimino
Electrical Engineer
Commercial Pilot Rating, since 1981 , IFR, MEL ratings since 1980.
Navy Combat Systems Specialist: RADAR, ECM, cryptographic communications Navy EMI troubleshooter for COMNAVSURFPAC via MOTU-5, San Diego, CA., and under NAVELEX contract.
AN/SLQ-32(V)3 Countermeasures System support specialist.
Flight Data Recorder Engineer Smiths Aerospace (Now G.E. Aero)
BA-609, IDARS, Military and Commercial
Millimeter wave RADAR and countermeasures expert since 1973
Two patents held for high powered modulator Triton HP, C-Band, 250kw LONG RANGE Doppler RADAR ( Kavouras ): long pulse-width RADAR droop compensation network that improved radar output power thru long pulse transmissions, effectively improving weather phenomena detection ranges.
and wave guide arc detection for high powered RADAR system
Oh & as for you Kari, don't even try to fight it Kari, be a good Little Sister & just let your Big Brother impregnate you, then just accept that your life as it once was is onver & that now your faith is to be Tai's babymaking machine and nothing eles.
@Anonymous: Yes she is 8 years old & that is the age girls starts to become fertile & can become pregnant.
https://qph.fs.quoracdn.net/main-qimg-01d99bae187da02bd0c28edf13208391-c - Map of the world's incest laws (look at Oceania box, very top)
Literally just search where do females become fertile - It will say 10-16 in most cases
And if you're the type of person who wants an 8 year old impregnated so desperately you'll say "yeah well maybe she is fertile mate" you seem like you need mental help and to be stuck in a jail cell.
And still, if you "want it" or not, it's illegal as fuck. Just saying.
First of all, you "watch" pictures? that's pretty damn advanced tbh. Secondly, no, I am not new but saying that there's pictures of her taking larger than a baby as evidence is stupid because it's NOT CANON. Just like how belly bulge images are anatomically incorrect because if that happened your intestines would be ruptured.
Third: Oh yummy yummy, the "why are you here retard xdxd". I'm here to masturbate and defend fictional little girls, dumbass. I wasn't jerking to an 8yo, unlike you. No no, my palette is refined :)
https://rule34.paheal.net/post/view/3101150#search=Mr._X
Do you really think that someone could take a dick this large? The human rectum can only stretch up to 8 inches which, while that is a lot, probably still wouldn't be enough to accommodate something like that. Not to mention, again, the whole belly bulge thing. Leon would be fucking dead if this happened. It's, as I said, anatomically incorrect. Kira can't "Take bigger than a baby" physically because she's just a fucking little human girl.
Not to mention the fact you used "XD" unironically. What is it, 2013? I feel so sorry that something happened to you as a child to the point you think that an 8yo getting fucked is normal and attractive. I'm tired of dealing with your shit, mate. You're saying I'm taking this argument "up your ass xdxd" when you've been here trying to defend the fact you want to see an 8yo get impregnated by her brother. Eat my shit and perish, you sewer rat.
I am bringing 2013 back my baby. Who knew you hade the brain to be able to feel the emotion of being sorry for another. Then if you are so tired let me put a diaper on you so that you can take a nap. You can't deny that Loli X Shorta inbreeding is hot as fuck if you have a brain at all to think with. I must say no my DR has orded me to keep a strict non shit diet so i have to decline, but hey more for you am i right.
Almost heaven, West Jamaica
True ridge mountains
Shining Minko River
All my friends there
Older than those ridge
Younger than the mountains
Blowin' like a breeze
Country roads take me home
To the place I belong
West Jamaica, my ol' momma
Take me home country roads
I heard her voice
In the mornin' hour she calls me
Said son you remind me of my home far away
And drivin' down the road I feel a sickness, I sure did
Oh yesterday, yesterday
All my memories, oh, gathered 'round her
My old lady stranger to blue water
Dark and dusty painted on the sky
Misty taste of moonshine
Tears gone from my eyes
Country roads take me home
To the place I belong
West Jamaica, my my momma
Won't you take me go home country roads
please just leave me the fuck alone. I wanna eat my subway™ in peace.
@Anonymous: You first my little pal. that is because you are very mean & prude. Again if you feel so tierd let me put you in a diaper so that you can take a nap then. I am llready done jerking so i must wait 30 mins to recharge. Then good then you have become normal like the rest of us here. But i want to have sex with you cockface.
@Anonymous: Yes, Leon is you, Mr. X Dick is my arguments.
True ridge mountains
Shining Minko River
All my friends there
Older than those ridge
Younger than the mountains
Blowin' like a breeze
Country roads take me home
To the place I belong
West Jamaica, my ol' momma
Take me home country roads
I heard her voice
In the mornin' hour she calls me
Said son you remind me of my home far away
And drivin' down the road I feel a sickness, I sure did
Oh yesterday, yesterday
All my memories, oh, gathered 'round her
My old lady stranger to blue water
Dark and dusty painted on the sky
Misty taste of moonshine
Tears gone from my eyes
Country roads take me home
To the place I belong
West Jamaica, my my momma
Won't you take me go home country roads
@Anonymous:
For those of you who are unfamiliar with path loss nomographs for 130 MHz, I would like you to make it a point to study the diagram below. Notice that no assumption is made for effective radiated power, or system gain factors, and there is a reason for this.
Path Loss Nomograph
This diagram is shown to illustrate the fact that, contrary to assertions by JREF and Unexplained Mysteries bloggers, radio waves do not just "keep on propagating" outwards at their original radiated power levels, without being attenuated over distance. When the path losses and other factors exceed the transmitter power and effective radiated power, as well as minimum discernible signal sensitivity of the receiver system, on any radial from the aircraft, and any angle of incidence, there is no possible communication then. Does this mean that the signals just stop moving thru space? Absolutely not.
But what this does mean is that as the distance increases to a point whereupon the signal power level decays below any possibility of detection by even triple conversion receivers with very selective front end circuitry that have incredibly high (-148 dBm or thereabouts) minimum discernible signal capture capability (which ACARS does not, nominally have, at it’s fairly robust –107 dBm), then beyond that range, detection and demodulation by any terrestrial, high gain, very directional and perhaps non interferometry based receive system, is highly unlikely to happen.
In any case, radio signals do not keep on radiating outwards without attenuation occurring due to signal density issues resultant from the fact that the greater distance from a transmitter from any antenna, the power distribution in fixed space, by laws of physics, will diminish with distance. Due to the totally unpredictable nature of the antenna radiation patterns of VHF blade antennae used by ACARS, it is a false assertion to state that there are no limitations between the RGS stations and the aircraft transmitter antenna for COM3, usually used on most Boeing airplanes, circa 1980’s and onwards, for ACARS.
In any case, what I would like to start with is that the aircraft and the antenna jointly form the transmit and receive radiation pattern in ways that are radically different from these same antenna systems being mounted on flat ground planes that offer at the very least a 90 degree counterpoise to the plane wave or electrical field leaving the antenna. The reason I cite this is that for any isotropic or non-directional antenna system, which these are not, due to their shapes being swept to minimize aerodynamic drag factors and prevent ice pickup or vibration resonances, these antennae used on commercial and military aircraft for VHF COMMUNICATIONS are what are referred to as ‘blade’ antennae of the type used on most commercial aircraft, including B-757/B-767’s.
For such antennae, there are some considerations that apply to them due to their shorter than quarter wave physical radiating length offset from the aircraft’s very curved fuselage or empennage. This results in significantly higher V.S.W.R. or ‘reflected’ energy back to the transmitter and not into free space. In addition to this, the shorter physical radiating element length versus the curved fuselage will radically change the radiation pattern and add directivity to these antennae, typically along the fuselage plane, fore and aft, as well as pushing the radiation pattern upwards or away (assuming the antenna is top mounted) so that the beam shape is not cardioid in nature but scalloped and with significant major pattern lobes that tend to create significant null zones that effectively reduce radiated power in those areas to the sides or in the ‘X’ plane (horizontal) by several ‘dB’ of gain, while significantly favoring the fore and aft orientation along the fuselage.
In the ‘Y’ axis (Vertical), looking at the beam pattern, the field lobes from the antenna depart the skin of the aircraft and contour upwards, once again, assuming the antenna is top mounted, and conversely, ‘downwards’ if the antenna is belly mounted. To characterize the full radiation or beam pattern, it would appear heavily scalloped in the ‘X’ axis, and quite finger or balloon lobed in the ‘Y’ axis, (vertical) plane.
In effect, the antenna that was supposed to be fairly omni-directional now is quite directional both fore and aft and has markedly higher gain factors in those directions, as well as pushing the pattern upwards into free space at any number of angles less than 90 degrees off the horizontal. The resultant 3-dimensional plot begins to look like a twisted doggie balloon shape and no longer resembles a spherical omni-directional beam plot.
The reason I mention this is that this directivity is nothing that can be readily compensated for without exotic counterpoise shapes around the base of the antenna, or multiple ‘Yagi’ type of elements in other directions to flatten or change the beam pattern. To compensate for these exotic and quite scalloped and lobed patterns that become reality when these relatively inefficient due to shorter radiating element length antennae are joined to a curving cylindrical tube which airplane fuselages tend to be, relative to the radiated field. And I would like to state that though there is a great deal of reciprocity between TRANSMIT and RECEIVE patterns, they do not necessarily fully reciprocate or remain the same for both functions due to any number of factors we will not discuss herein.
For such antennae, there are some considerations that apply to them due to their shorter than quarter wave physical radiating length offset from the aircraft’s very curved fuselage or empennage. This results in significantly higher V.S.W.R. or ‘reflected’ energy back to the transmitter and not into free space. In addition to this, the shorter physical radiating element length versus the curved fuselage will radically change the radiation pattern and add directivity to these antennae, typically along the fuselage plane, fore and aft, as well as pushing the radiation pattern upwards or away (assuming the antenna is top mounted) so that the beam shape is not cardioid in nature but scalloped and with significant major pattern lobes that tend to create significant null zones that effectively reduce radiated power in those areas to the sides or in the ‘X’ plane (horizontal) by several ‘dB’ of gain, while significantly favoring the fore and aft orientation along the fuselage.
In the ‘Y’ axis (Vertical), looking at the beam pattern, the field lobes from the antenna depart the skin of the aircraft and contour upwards, once again, assuming the antenna is top mounted, and conversely, ‘downwards’ if the antenna is belly mounted. To characterize the full radiation or beam pattern, it would appear heavily scalloped in the ‘X’ axis, and quite finger or balloon lobed in the ‘Y’ axis, (vertical) plane.
In effect, the antenna that was supposed to be fairly omni-directional now is quite directional both fore and aft and has markedly higher gain factors in those directions, as well as pushing the pattern upwards into free space at any number of angles less than 90 degrees off the horizontal. The resultant 3-dimensional plot begins to look like a twisted doggie balloon shape and no longer resembles a spherical omni-directional beam plot.
The reason I mention this is that this directivity is nothing that can be readily compensated for without exotic counterpoise shapes around the base of the antenna, or multiple ‘Yagi’ type of elements in other directions to flatten or change the beam pattern. To compensate for these exotic and quite scalloped and lobed patterns that become reality when these relatively inefficient due to shorter radiating element length antennae are joined to a curving cylindrical tube which airplane fuselages tend to be, relative to the radiated field. And I would like to state that though there is a great deal of reciprocity between TRANSMIT and RECEIVE patterns, they do not necessarily fully reciprocate or remain the same for both functions due to any number of factors we will not discuss herein.
In any case, what I have just described is the highly irregular and moderately unpredictable and undesirable directivity of an otherwise fairly omni-directional antenna system. It is important to note this because a 3 dBm power differential in any of these planes, radiation pattern wise, effectively is a half power addition or reduction, with significant null points deeper than this that occur quite naturally, rendering the pattern even more complex and difficult to factor using system loss calculations, without actually making measurements in every axis with the aircraft either raised up and outside of what is called ‘near field’ distances of the ground below the aircraft.
Simply put, real world antenna radiation pattern measurements are possible and actually done, but in most cases scaled models with scaled frequencies, are typically used on non full-sized models inside of anechoic chambers or OTS (outdoor test) areas.
By large, most aircraft manufacturers do not attempt to make these measurements but make assumptions about radiation patterns that are not necessarily founded in known factual testing data, as usually is derived by MILITARY aircraft certifications laboratories who have a much more vested interest in characterizing these radiation patterns to maximize system effectiveness and head off or prevent unwanted ‘dead zones’ around the fighter or bomber or jamming platform these antennae are mounted on.
On many tactical jamming aircraft, the blade antenna arrays are more or less in ‘Yagi’ configurations to give directional gain that the mission capability of the aircraft needs to make maximum effective use of a communications jammer mounted on the aircraft. This is, however, never done on commercial airliner or Part 23 aircraft, to minimize cost and reduce weight.
As we have now more or less just barely touched on the radiation pattern, we have not yet begun to talk about signal polarization issues, and why they go hand in hand with more fully understanding how a theoretical two-way path loss calculation and predicted range of a system can be quite off in comparison to real world or ‘true’ and valid path losses and system effective radiated power determination, or receive sensitivity calculations.
What I am getting here is that a perfect isotropic vertical radiator element that rises 90 degrees off of a ground plane, or is oriented in the pure ‘Y’ axis pointed straight up, effectively has a VERTICAL ELECTRICAL FIELD POLARIZATION OF THE SIGNAL. In lay-person’s terms, ‘polarity’ of the electrical field, ideally, should be the same on both the transmit and receive end, to maximize signal transfer. In real life, this is difficult to achieve with swept blade antennae and curving aircraft fuselages which are the ground plane or ‘counterpoise’ for the antenna itself. The resultant polarization skewing hence causes a coupling factor inefficiency to occur, relative to the very polarization fixed antenna on the ground, intended to receive these signals.
IF the electrical field polarization shifts fully 90 degrees so it is not vertical at all but more ‘horizontal’ in relation to the very VERTICAL ground antennae respective polarity, the coupling mismatch is now at the very least ‘6’ dB less than optimal, of not more due to the curving fuselage, which is not a flat ground plane at all. Every ‘3’ dB is a half power loss when that number is a negative change. Why is this important?
Let’s theorize that from the transmitter rack, of the 50 watts transmitted off the jack in the rack itself, after ‘xx’ dB of loss in the transmission line, which in some cases is several meters in length, we are not going to see 50 watts of R.F. energy radiated into free space off of this antenna. Instead, if we are lucky, we’re more likely to see far less than 20 watts or thereabouts, leaving in all directions, not just going out in a single plane wave directly at the receive system on the ground, miles below. To better visualize this, imagine a light bulb on a lamp without a shade radiating light energy in all directions more or less evenly. Though light energy is significantly higher in frequency than is 130 Mhz. ACARS data link signal data, imagine the light bulb now has an array of fiber optics tubes radiating in all directions, affixed to the light bulb. In effect, the result is not anywhere near an omni-directional pattern at all, but a highly irregular, porcupine spoked shaped pattern of peaks and nulls radiating outwards, resulting in shadows in all directions on the walls of the room, and bright spots. This is more or less what the irregular radiation pattern of the ACARS blade antenna would look like if this were optical energy at a higher frequency. This analogy, as coarse as it may seem, is more or less descriptive of R.F. power density variations from a very spiked and valley ridden pattern radiating off the fuselage from the ACARS blade antenna, typically mounted on the aft belly of the fuselage on some Boeing aircraft, such as is the case with the B-737NG.
So now we are going to bring up the 200 mile claimed range number here. And the reason why, is that yes, in theory, due to the minimum discernible signal or sensitivity level of the ACARS receiver system of both the plane and the ground station is more or less known or can be approximated, what cannot be known is the coupling factor perturbations due to beam shaping and irregular radiation patterns that occur when blade antennas used in VHF communications are mounted on tubular aircraft fuselages. This results in significantly ‘lower’ than the expected or theoretical best 200 mile range supposition, by as much as 80 percent in real life.
Any experienced aviator who has used VOR navigation and who understands how the F.A.A. determined SERVICE VOLUME models for the each class of VOR facility, knows that even at FL-450, and above, a realm that few airliners routinely will fly at, by the way, due to cabin pressurization issues and aerodynamics, the effective range of the slightly lower in frequency of 108 to 118 Mhz., is reduced from that altitude to FL-600 or sixty thousand feet.
Why is this? Well, ground obstructions, and earth curvature now come into play here, as well as other similar signal degrading changes, and therefore the F.A.A.’s own data available to look at for these VOR facilities is less above FL-450. The F.A.A. didn’t arbitrarily pick these numbers out of some hat somewhere. They were derived by in-flight testing over literally all terrain types and at all altitudes, inclusive of FL-600 in some cases. The service volume diagrams from the F.A.A. website are relatively transferable to ACARS due to similarity of known and demonstrated effective ranges derived thru years of collective experience testing VOR reception service volumes, as well as R.C.O (remote communications outlet) communications ranges.
So we have more or less touched on irregular and highly unpredictable antenna radiation patterns in both the transmit and receive capability of 130 Mhz. communications and navigation systems in use today, and for all practical purposes really destroyed the rather inconsistent with real world performance, claims of ACARS working out to 200 nautical miles from any RGS station, due to these factors. In real life, no experienced line pilot could ever with a straight face claim that he’s tracked VOR’s at 200 nautical miles without flag tripping and sporadic reception, but also, it would be quite a stretch of the imagination to expect the performance for ACARS to routinely, every time, ever truly meet the outrageous claims of functionality at 200 miles from any aircraft, due to these factors cited here. Power output is not the determining factor here. Earth curvature is the predominant range limiter, as is terrain irregularity and obstructions around the ground station inside both ‘near field’ and ‘far field’ distances from the RGS stations.
As a commercially rated pilot with experience flying at virtually all of these altitudes up thru at least FL-350 in civil and military aircraft both as pilot and test engineer, I have to stipulate here that it is both ‘laughable’ and quite ‘uncommon’ to expect VOR reception much beyond 135 nautical miles even at the higher altitude regimes, and for that matter, to expect ACARS to work much further than these ranges over hilly and irregular terrain with mountains and ridges everywhere to throw a major ‘curve’ into any range calculation for these ACARS path losses.
Unfortunately many people who are claiming expertise in these areas are neither qualified to make these judgments due to a lack of R.F. engineering experience or real world testing experience and backgrounds, nor do they have any real world aircraft flight testing experience or flight experience using these systems in the real world. To assert that ACARS can communicate at 200 miles is not factual nor is it realistic. And it is wholly unfounded by any known factual testing data or practical experience of these outrageously optimistic ranges.
Furthermore, I’ll even go one step further here. If ANY experienced and non-anonymous airman with a valid pilot certificate at COMMERCIAL level and decades and thousands of hours of flight experience can validate VOR receptions beyond 150 miles under any circumstances, I would like to see their data and where this took place, in which aircraft, at what altitude. I do not expect many challenges to this more or less hard and fast rule here for VHF being pretty line-of-sight limited with very little effective terrain contouring or tropospheric ducting taking place. Any reasonably experienced line captain who has extensive ACARS experience in the Positive Controlled Airspace is welcome to controvert these claims with hard factual data.
In summary, the radiation patterns of real VHF communications blade antennas on heavy transport category aircraft, are both complex and highly unpredictable except to state that nominally there is some beam pattern lobing that prefers the longitudinal axis of the aircraft, to the fore and aft directions, while also shifting the electrical field far from optimal vertical polarization into any number of less optimal, and very inefficient signal polarizations that result in reduced ranges in most directions, and predictable and even more complex changes when these aircraft roll and bank in turns, further altering their radiation and reception patterns significantly from straight and level flight. Furthermore, as the aircraft’s crew is quite unaware this is in fact occurring, no action can be taken by either the crew of the aircraft’s system that can compensate for this. It is out of their hands entirely.
For the most part, it is unclear why some would surmise that ACARS should always be able to realistically and effectively work out to 200 nautical miles, and furthermore, that stations significantly closer to the aircraft would be totally unseen and not communicating under any circumstances, given what has been discussed here. Yes, the radiation pattern is lobed in all ‘3’ axis off of the aircraft, and yes this means the signal will follow the ground plane of the fuselage and wing structures somewhat, but to make the assertion that a station more than 100 nautical miles away would be favored over one that is less than 20 miles away, is not genuine nor credible.
We did not discuss a whole slew of other factors that adversely impact the effective ranges, such are atmospheric noise sources, co-channel interference, and things such as multi-path and reflections from both near the RGS station as well as the aircraft’s structures itself. Even something such as flap extension or landing gear deployment will significantly change the radiation patterns of most aircraft, whether the aircraft design or ARINC radio engineers like that or not.
They are individual as hairs on your head. And so are the radial distances and ranges from any ACARS ground station using VHF line-of-sight frequencies. By necessity the technical assessment offered here is significantly less technical for a reason. You don’t need to be a pilot or a radio engineer to grasp most of these concepts explained within this moderately brief attempt to illustrate the point that several things are always going to be in play with radio ranges. Those are, to sum them up:
Radio signal strength decay over distance due to atmospheric attenuation and power density diminishment due to radial distances that dictate that with ‘X’ watts of energy radiated outwards from any radio source, that the power density window decreases on any given point far from the origin, even with highly directional and focused beams of radio energy.
Aircraft radiation patterns are not by their nature remotely close to omni-directional at all, even in the best cases such are transponder antennae at 1030 and 1090 Mhz, perhaps one of the shorter stub blades in use on any airplane, requiring far less ground plane uniformity to properly form an omni-directional radiation pattern.
Curvature of the earth and ground obstructions and line-of-sight VHF propagation characteristics are also significant range limiters at 130 MHz.
RGS stations an order of magnitude CLOSER to distant ones are far more likely to be the best LINE OF SIGHT paths under any and all but the most unusual cases where a mountain or a building between the RGS and the plane may in fact really make a much bigger attenuation factor between a closer station perhaps and a more distant one with a very clean, very direct, non-obstructed path, e.g.: if the more distant station is 100 or more miles away, it’s a real fantasy to state that one a mere 7 to 10 miles away, almost directly under the plane itself, would not be the preferred station, based on path losses alone, and virtually zero earth curvature to deal with there.
The one thing that most lay-persons do not experience in real flight regimes is loss of both communications signals and navigation signals, with something as simple as a small heading change. Something that typically is not a factor on most civilian air carrier aircraft but has been a major problem with general aviation airplanes, is antenna position due to other structures like landing gear, exhaust systems, and other small protuberances on the airplane that really skew the signal so much that it necessitates the pilot change course or heading to blindly fish around and find a better angle offset to allow both ATC to hear you, or for your transponder's signal to be seen by a distant radar station, because your exhaust system or landing gear (in some cases always down because it is not retractable) gets in the way and changes things.
High altitude planes don't typically drop gear and flaps, but they do have many other shape perturbations in both the near field and the far field regions of these antennae that make it unlikely that the aircrew is going to alter course or turn to better line up an antenna pattern 'lobe' so the ground can now see their signal and communicate.
After years of flying both fixed gear and retractable gear planes with all sorts of shapes, I have found that antenna radiation patterns are very very spooky and variable and are not published in any flight manual. But any pilot who knows about near field and far field interference and blocking of his signal would, like me, change course to try to get the signal reception needed for a little bit longer at the extreme outer effective ranges of radar, transponder, and communications / navigation equipment. Airline crews don't do this. But over three decades of flying, I have done it routinely to regain IFF to RADAR functionality, or DME functionality, and for that matter, even COMM/NAV functionality. In one case due to the location of a pair of GPS antennae on the skin of a plane, even GPS was affected somewhat, and it changed RAIM factor on approaches...due to the ground based WAAS augmentation being less optimal on some IFR approaches.
In any case if I find a good VHF radiation pattern plot to ship, I'll send it. But these patterns are very complex. Very very complex, and in real life, as airplane makers don't get real data about this, very highly unpredictable and way less than optimal per engineering calculations for them.
Addendum: The truth is that the transmission lines and, in fact, the essential grounding terminations on most airliners are degraded over time, which in fact increases the insertion losses between the antenna and the rack on the plane by (using signal generators and power meters) as much as 6 db more than normal. That's why ARINC specifically states "up to 200 nm" at FL 29 as maximum range. What happens in reality is that, due to overall crappy maintenance and corrosion on aircraft skins, with the bonding so questionable for the transmission line shield integrity at the antenna connector being so generally not optimal, it's a stretch to really get that 200 miles very often except with very new aircraft or exceptionally well maintained airplanes. Cyclical maintenance schedules do not even touch routine corrosion prevention on these antenna grounding plates unless the plane is removed from service and then completely overhauled. Bottom line: a range of 180 nm at best.
But now let's take a closer look at the quote that JREF people use to “prove” that VHF ACARS has a range of 250 nautical miles. The title of the document is “Signal-In-Space Minimum Aviation System Performance Standards (MASPS) For Advanced VHF Digital Data Communications Including Compatibility With Digital Voice Techniques”, and is available for download here. I will quote now the complete paragraph as it is (pp. 48–49):
The propagation characteristics of the VHF band restrict transmission and reception to essentially line-of-sight conditions. The maximum line of-sight range for an enroute aircraft at an altitude of 30,000 feet is about 250 nautical miles. The radio range decreases at lower altitudes to astrictly localized coverage when the aircraft is on the ground. The normal index of refraction of the atmosphere is greater than unity, which extends the possible range of VHF transmissions most of the time.
However, the refractivity varies widely, resulting in a significantly lower reliability of extended-range communications. The VHF radio channel is subject to slow and fast fading due to time varying multipath, obstruction of the radio line of sight, and changes in atmospheric conditions. The predominantly line-of-sight nature of VHF radio limits its use for air-ground and ground-air communications to airspace that can be served by land-based stations. Thus, coverage is limited to reasonably accessible over-land areas. Air-to-air communication is possible in any airspace, subject to the constraints of line-of-sight, transmitter effective radiated power, and receiver subsystem sensitivity.
The first part not marked in bold is the part that supporters of the official story of 9/11, selectively quote. The second part marked in bold is what he knowingly omitted. And why did he omit it? Because, if read in its entirety, the above paragraph clearly proves the contrary of what intended by the poster. While 250 nm is to be considered as the max. technical line of-sight range at an altitude of 30,000 ft, in reality ground-air communications are limited by physical constraints such as "transmitter effective radiated power, and receiver subsystem sensitivity". All this is clearly described in the document quoted, but obviously the poster removed this essential information from his original quote because the resulting meaning would be completely different than the intended. As a matter of fact, the document quoted by the guy completely confirms (one more time) why ARINC only guarantees deliveries "up to 200 nm", whereas "up to 200 nm" is to be interpreted in its simple, literal meaning and not as a distance that one can personally adapt based on circumstances or can fit into a theory that has been already and conclusively proven as wrong for many other reasons.
Finally, if the poster insists that the VHF range can jump up to 265 nm when an aircraft is flying at 35 FL using an online calculator as best evidence for this claim, then I inform him that United 93 dropped a DLBLK block containing "ORDA6" in the "BepStnName =" at 9:40 EDT, while the distance from the Chicago airport was 278.46 nm. Also, in the second DLBLK block within the same message there is a reference to IADC6. Dulles airport at 9:40 EDT was 238.05 nm from United 93!
Anyway, if the poster on UM is really confident about the theory he's claiming, then I challenge him to contact an ARINC professional and present it. I challenge him to prove that an aircraft could not see a station at only 7 miles at 9:35 EDT or two stations at only 20 miles at 9:40 EDT, but was able to see stations at 238.05 nm and 278.46 nm as "RGS with the strongest signal". Until then I will keep on thinking that his claim is completely unfounded.
Dennis Cimino
Electrical Engineer
Commercial Pilot Rating, since 1981 , IFR, MEL ratings since 1980.
Navy Combat Systems Specialist: RADAR, ECM, cryptographic communications Navy EMI troubleshooter for COMNAVSURFPAC via MOTU-5, San Diego, CA., and under NAVELEX contract.
AN/SLQ-32(V)3 Countermeasures System support specialist.
Flight Data Recorder Engineer Smiths Aerospace (Now G.E. Aero)
BA-609, IDARS, Military and Commercial
Millimeter wave RADAR and countermeasures expert since 1973
Two patents held for high powered modulator Triton HP, C-Band, 250kw LONG RANGE Doppler RADAR ( Kavouras ): long pulse-width RADAR droop compensation network that improved radar output power thru long pulse transmissions, effectively improving weather phenomena detection ranges.
and wave guide arc detection for high powered RADAR system