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AAE Antennas

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TELEDYNMCS(at)aol.com
Guest

Posted: Fri Jan 23, 2009 5:09 am Post subject: AAE Antennas

In a message dated 1/23/2009 3:13:54 A.M. Eastern Standard Time,  europa-list(at)matronics.com writes:

  	  Quote: 	
		  I have    installed all three but prefer the carbon fiber Advanced Aircraft    

Electronics (AAE) antenna types because they are "no  brainers". 	
  

 Hey Bud,

  

 I will second that! I have both an AAE Com and an AAE transponder antenna  on N245E and I couldn't be more pleased with them. (and I'm a picky RF  engineer by trade). I've swept the Com antenna alone across the band and  the SWR remains flat at about 1.38 to 1 end to end. I also swept the  transponder antenna at 1090 Mhz and it shows excellent SWR characteristics, too.  The AAE folks were outstanding to deal with. I originally purchased the Com  antenna with a 90 degree BNC connector take off.  I decided six  months after I purchased my Com antenna that I really needed a straight  BNC take off for proper cable routing. So, I contacted them and they  swapped the antenna at no charge and even paid the return shipping!

  

 My AAE Com is mounted on the aft side of the tail post. I made a 1" square  hole in the center of tail post for the  antennas connector/splitter assembly to pass through the tail post,  then attached the elements of the antenna to the rear of the tail  post with silicone after scuffing the tail post a bit to enhance adhesion.  The coax feed routes through the center of the bottom rib of the vertical  fin through a small, grommeted hole and forward into the  fuselage. Both transmission and reception are excellent using this antenna  coupled to a Garmin 250X GPS/Com.

  

 Regards,

  

 John  Lawton

Whitwell, TN (TN89)

N245E -  Flying

 A Good Credit Sco55013x1201028747/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=62%26bcd=DecemailfooterNO62"> See yours in just 2 easy steps!

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fklein(at)orcasonline.com
Guest

Posted: Fri Jan 23, 2009 11:18 am Post subject: AAE Antennas

On Jan 23, 2009, at 5:06 AM, TELEDYNMCS(at)aol.com (TELEDYNMCS(at)aol.com) wrote:

 	  Quote: 	
		  My AAE Com is mounted on the aft side of the tail post. I made a 1" square hole in the center of tail post for the antennas connector/splitter assembly to pass through the tail post, then attached the elements of the antenna to the rear of the tail post with silicone after scuffing the tail post a bit to enhance adhesion. The coax feed routes through the center of the bottom rib of the vertical fin through a small, grommeted hole and forward into the fuselage. 	




John,

Thanks for another astute and valuable contribution...geeze...to think the com antenna can be a simple vertical strip tucked between the rudder and stern post...what a sweet and simple solution. And I'm sittin here lookin at the Bob Archer big "E"...all doable and functional I'm sure...but sweet?...not so much.

When you say, 

		"The coax feed routes through the center of the bottom rib of the vertical fin through a small, grommeted hole and forward into the fuselage"...

....it sounds like the coax traces an "S" curve before it starts its run forward...am I understanding your installation correctly? I thought one of the goals w/ antenna coax routing was to eliminate bends.

With your expertise, I hope you can answer a couple of nagging questions I've had:

- I'm planning on running a tail light/tail strobe at the highest point on the rudder trailing edge; will these wires (running down the back side of the stern post) create electronic interference if I were to adopt your antenna solution?...what about the same if I were to install the Bob Archer in the fin?...or should I move the BA forward of the rear bulkhead to where there would be adequate height within the fuselage shell?

Thanks,

Fred

A194

--  This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.   [quote][b]

paul.the.aviator(at)gmail
Guest

Posted: Fri Jan 23, 2009 12:07 pm Post subject: AAE Antennas

Hi Fred,



I used a Bob Archer in my fin with the strobe on top of my fin.  I

haven't had any noise issues with this combination.



Paul



 	  Quote: 	
		   - I'm planning on running a tail light/tail strobe at the highest point on

 the rudder trailing edge; will these wires (running down the back side of

 the stern post) create electronic interference if I were to adopt your

 antenna solution?...what about the same if I were to install the Bob Archer

 in the fin?...or should I move the BA forward of the rear bulkhead to where

 there would be adequate height within the fuselage shell?

 Thanks,

 Fred

wilwood(at)earthlink.net
Guest

Posted: Fri Jan 23, 2009 12:42 pm Post subject: AAE Antennas

Paul,



Your Archer antenna is working well.  



Back on Feb 12, 2006 you posted:



I have a Bob Archer antenna in the tail of my Europa.  My trim control &

Navaids go nuts when I transmit and I haven't ever solved the problem.



How did you solve that problem?



Thanks,

Bill Mcclellan



--

paul.the.aviator(at)gmail
Guest

Posted: Fri Jan 23, 2009 2:20 pm Post subject: AAE Antennas

Hi Bill,



I fixed the navaids issue by moving the nav antenna. If I was to do it

over I would put my VOR antenna in the wing so it was away from other

stuff and would not need to be folded around the fuselage to fit.  The

downside is that this means one more cable to connect when the wing

comes off and on, and if the antenna should fail for any reason,

getting to it would be difficult.



I improved the intercom by using shielded cable, although once in

great while it will lock up the intercom (micro processor based) with

a stuck mike.  This ONLY ever happens when I am talking to a busy

sector with ATC, and never happens when I am flying out of a deserted

grass field strip with no one around.



As far as the trim indicator goes, I never bothered to look into it.



The antenna works well, but I have nothing to compare it to.  The

noise issue I was referring to in my last post was induced noise from

the strobe cable being near the antenna.  For my installation it

hasn't been a problem.  Trying to fit a Bob Archer in the fin of a

Europa is a bit tricky, it sounds like at AAE would be easier.  I seen

to recall that I saw similar SWR's over the entire frequency range,

something like 1.4 to 1 being the worst case.  I was surprised to see

it so flat over such a broad range, mind you, the SWR meter was a very

inexpensive one off eBay, so its accuracy could be called into

question.



Cheers,  Paul

TELEDYNMCS(at)aol.com
Guest

Posted: Sat Jan 24, 2009 4:21 am Post subject: AAE Antennas

In a message dated 1/24/2009 3:13:23 A.M. Eastern Standard Time,  europa-list(at)matronics.com writes:

  	  Quote: 	
		  >>>> I'm planning on running a tail light/tail strobe    at the highest  

point on the rudder trailing edge; will these wires    (running down the  

back side of the stern post) create electronic    interference if I were  

to adopt your antenna    solution?.<<<< 	

 Hey Fred,

 The way to make a highly directional antenna out of a dipole is to put a  metallic object parallel and in close proximity to the antennas  elements. I would avoid putting any metallic objects, particularly along the  entire length of the antenna elements, that are within 2 wave lengths  distance from the antenna. If you do this you will likely change  the radiation pattern of the antenna considerably and you risk having blind  spots, along with poor transmit and receive characteristics. The two wave  length distance is a general rule of thumb. Whether or not your strobe  wiring will interfere also depends on your radio's noise rejection  characteristics. Noise rejection characteristics vary from radio to radio and  manufacturer to manufacturer, but one thing is certain. Aircraft Com radios  are AM and that does not bode well for noise rejection at all, regardless of who  made it. I would try to keep your strobe wiring and the light itself as far away  as possible from antennas and audio wiring and be sure to ground the  strobe shield wire on one end, preferably to the case of the strobe power  supply, such as under one of the mounting bolts so that the shield wire contacts  the case of the strobe power supply.

  	  Quote: 	
		  >>>>..what about the same if I were to  

install    the Bob Archer in the fin?...or should I move the BA forward  

of the    rear bulkhead to where there would be adequate height within  

the    fuselage shell?<<<<< 	

 Consider antenna accessibility if you are thinking of placing it  inside the vertical fin. There might come a time at some point in the future  where you will need to get at it. This isn't likely, but it would be my luck if  I were to place an antenna in an inaccessible area I would have to get to  it for some reason. I would think that would result in major surgery if you  install it inside the fin above the bottom rib. One of the reasons why I  put my AAE Com antenna on the back side of the stern post was for  accessibility. For installation forward of the rear bulkhead, again you  have to consider the metallic objects that are in close proximity, i.e.,  elevator push/pull tube, elevator mass balance, etc. One solution might be to  install your Com antenna right behind the "D" panel in the baggage bay bulkhead.  You're only radiating about 5-8 watts with the Com, so there isn't much of an RF  hazard to consider. The transponder antenna is one I would want as far away as  possible from me, audio wiring, and other  electronics that might be sensitive. Some transponders pulse as  high as 250 watts ERP. 1090 Mhz at that power level is certainly something to  consider.

 Hope it helps!

 Regards,

 John  Lawton

Whitwell, TN (TN89)

N245E -  Flying

 A Good Credit Score is 7201028747/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=62%26bcd=DecemailfooterNO62"> See yours in just 2 easy steps!

  [quote][b]

houlihan(at)blueyonder.co
Guest

Posted: Sat Jan 24, 2009 5:18 am Post subject: AAE Antennas

Hi John



Your comments about power output are correct, but you have to include in 

your calculations that the AM comms radio transmitts for as long as you 

press the PTT wich could be for several tens of seconds whereas the 

Transponder  replies  with a number of very short  pulses  in the range 

of microseconds when replying.

For sure the peak power is up to 250 watts  but the mean power is very low.

If you worry about that consider your cell phone working at 900 Mhz or 

so, its in your shirt pocket most of the time responding to updates from 

the base station every so often, and then you get it out and place it 

next to your ear and make continuous transmission's (its true duplex 

operation !) for several tens of minutes. And if you are on the fringes 

of a cell the power is ramped up to maintain communication.



Worry about more immediate things first.



Regards



Tim Houlihan

G-BZTH



P.S. my microwave experience is some years old so please correct me if I 

get it wrong !





TELEDYNMCS(at)aol.com wrote:

 	  Quote: 	
		    You're only radiating about 5-8 watts with the Com, so there isn't 

 much of an RF hazard to consider. The transponder antenna is one I 

 would want as far away as possible from me, audio wiring, and other 

 electronics that might be sensitive. Some transponders pulse as high 

 as 250 watts ERP. 1090 Mhz at that power level is certainly something 

 to consider.

  

 Hope it helps!

  

 Regards,

  

 John Lawton

 Whitwell, TN (TN89)

 N245E - Flying



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TELEDYNMCS(at)aol.com
Guest

Posted: Sun Jan 25, 2009 6:05 am Post subject: AAE Antennas

In a message dated 1/25/2009 3:11:55 A.M. Eastern Standard Time,  europa-list(at)matronics.com writes:

  	  Quote: 	
		  >>>>>For sure the peak power is up to 250 watts     but the mean power is very low.

If you worry about that consider your cell    phone working at 900 Mhz or 

so, its in your shirt pocket most of the time    responding to updates from 

the base station every so often, and then you    get it out and place it 

next to your ear and make continuous    transmission's (its true duplex 

operation !) for several tens of minutes.    And if you are on the fringes 

of a cell the power is ramped up to maintain    communication.<<<<< 	
  

 Hey Tim,

  

 You are correct that transponders pulses are short bursts. You are also  correct that your cell phone does update periodically from the overlaying  cellular system and does in fact transmit and receive from the  controlling cell routinely, regardless of whether or not you are making a  phone call. Often, you will hear the update happening on your car radio  speakers, for incidence. This updating is done to keep track of where the  mobile is in the system and to verify the mobile's authenticity and  registration within the system, among other reasons. 

  

 However, you are incorrect about "true duplex operation" of cellular  telephones. This is my primary area of expertise with RF and one with  which I am intimately familiar. Cellular, PCS and SMR operate half  duplex. The switch between transmission and reception on  your phone happens extremely fast, thus is usually imperceptible  to your ear in most cases. Occasionally, though, it is perceptible if you listen  closely. Ever noticed how two people talking at the same time  on a cell to cell call can't hear both sides of the conversation as you  would, say with a land line? Very often you have to repeat what was just  said if two people talk at the same time on a cell to cell call because only  half of the audio of the conversation is  being transmitted. This happens because your phone is operating half  duplex, not full duplex. This half duplex operation done for a variety of  reasons, but the primary reason these days is to extend the battery  life of your mobile. This scheme has been used since day one in the  USA when the original cellular protocol was implemented in the mid 1980's.  I would imagine it is the same in the UK since USA based GSM mobiles will work  in your country provided a local SIM chip is installed.

  

 Another point to consider is your hand held cell phone operates  at 6/10ths of a watt at it's maximum power level.  The "ramping up" you mention is referred to in the industry  as power stepping of the mobile. In urban areas where you are in close  proximity to the controlling cellular base station indeed your  phone will often operate at considerably lower power settings, then  step up to higher power levels as either you move farther away  from the cell, or as your mobile's signal as "seen" from the  controlling cell drops below predetermined levels because of physical or  atmospheric issues blocking or partially blocking your  phone's signal. With some digital transmission schemes, particularly  GSM and CDMA, power stepping is also employed in areas of dense RF  saturation.

  

 With this in mind, and coupled with skin effect, which is the tendency  for weak signals to pass around your body rather than through it because  your body is made up primarily of water, you are in no danger of ill  effects from a cell phone's non-ionizing radiation, even when held next to  your head. Remember, it takes 600-1000 watts of highly concentrated  microwave energy to pop a bag of popcorn or defrost tonight's roast for  dinner. Your cell phone radiates omni-directionally, so only a small  portion of the weak signal being transmitted is directed towards your  head when in use. Skin effect causes that weak signal to pass around, not into,  your head.

  

 Transponder antennae, on the other hand, in close proximity,  say closer than two wave lengths, do, IMHO, pose a  significant RF hazard when the exposure occurs repeatedly over a long  period of time, even with the short burst duration. This  is particularly true for those of us, like myself, who are  routinely exposed to high levels of RF. While the nominal power output  of a typical transponder is around 250 watts, peak power is usually rated in the  two kilowatt range and this does not take into account the gain of the antenna.  Granted, these are indeed short bursts, but why expose yourself to this power  level unnecessarily, even for short bursts? (unless of course, you are beyond  child bearing years or have no desire to father children) If you keep the  transponder antenna at least two wave lengths away from your body roughly 96% of  the energy is dissipated within this distance. Skin effect takes care of the  rest.

  

 There are certainly more pressing issues to consider when building  and flying our wonderful little birds. I didn't intend to sound as if  being exposed to 1090 Mhz transponder signals will cause you to grow extra  appendages. It certainly won't. However, unnecessary exposure to RF  certainly should not be ignored, Repeated exposure can damage  your retinas, among other things. I know several long time HAM  radio operators who wish they had heeded the warning. In this day and  age we are all exposed to a wide variety of RF. In fact, most people would be  very concerned if they knew first hand what they are exposed to in their day to  day lives. In my humble opinion, there is absolutely nothing wrong with  being cautious.

  

 Regards,

  	  Quote: 	
		     John    Lawton

Whitwell, TN (TN89)

N245E -  Flying

	
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houlihan(at)blueyonder.co
Guest

Posted: Mon Jan 26, 2009 2:56 pm Post subject: AAE Antennas

TELEDYNMCS(at)aol.com wrote:

 	  Quote: 	
		   With this in mind, and coupled with skin effect, which is the tendency 

 for weak signals to pass around your body rather than through 

 it because your body is made up primarily of water, you are in no 

 danger of ill effects from a cell phone's non-ionizing radiation, even 

 when held next to your head. Remember, it takes 600-1000 watts of 

 highly concentrated microwave energy to pop a bag of popcorn or 

 defrost tonight's roast for dinner. Your cell phone radiates 

 omni-directionally, so only a small portion of the weak signal being 

 transmitted is directed towards your head when in use. Skin effect 

 causes that weak signal to pass around, not into, your head.

  

 Transponder antennae, on the other hand, in close proximity, 

 say closer than two wave lengths, do, IMHO, pose a significant RF 

 hazard when the exposure occurs repeatedly over a long period of time, 

 even with the short burst duration. This is particularly true for 

 those of us, like myself, who are routinely exposed to high levels of 

 RF. While the nominal power output of a typical transponder is around 

 250 watts, peak power is usually rated in the two kilowatt range and 

 this does not take into account the gain of the antenna. Granted, 

 these are indeed short bursts, but why expose yourself to this power 

 level unnecessarily, even for short bursts? (unless of course, you are 

 beyond child bearing years or have no desire to father children) If 

 you keep the transponder antenna at least two wave lengths away from 

 your body roughly 96% of the energy is dissipated within this 

 distance. Skin effect takes care of the rest.

Hi John
	




Thanks for you very informative reply I was obviously wrong in assuming 

that cell phones are like real phones and carried two way conversations, 

but your description does explain those missing bits of the 

conversation. As I said before, my limited expertise was, 35 years ago, 

as an R.A.F. Airborne radar technician with a specialist radar 

countermeasures squadron. I do know how to change the SIM card and 

charge the battery of a Cell phone but that's the limit of my knowledge. 

Modern electronic devices are simply magic to me.



I feel I have to correct you when you state that the peak power is in 

the 2 Kilowatt range. I have checked a couple of spec sheets and to 

confirm things I phoned a major  transponder manufacturer just to make 

sure. Most transponders have a peak power of up to 250 watts not two 

Kilowatts.

For example the Trig TT21 has a mean power of less than two watts with a 

peak power of 140 watts at the unit connector. I am told that the duty 

cycle is less than 1 percent.

The worse one I saw had an input power of 27 watts total with a peak 

power of 250 watts. but none I saw had a peak power of more than 250 

watts. Remember this secondary not primary radar and the radiated power 

requirements are dramatically reduced

I think the comments about child bearing and fatherhood are difficult to 

justify at these low powers though at my age with children in their 

middle 30's this should not be a major issue for me !



The transponder aerial  is Omni directional so as you say only a small 

portion of the energy is directed at you, even less than with a cell 

phone held to your ear.

In a Europa, if the aerial is behind the baggage bay ( and the fuel 

tank) then it is more than likely greater than two wavelengths or 60cms 

(23") away from the crew.



Having said all that, I agree with you that we should try and reduce the 

risks its just that in the amateur built aircraft arena I think the 

risks from the transponder is well down the list of things to get 

excited about.



Tim Houlihan

G-BZTH

mikenjulie.parkin(at)btin
Guest

Posted: Mon Jan 26, 2009 3:15 pm Post subject: AAE Antennas

Hey Guys,



I just love all this technical stuff.  As the Ad says 'here comes the

science bit'.



Regards,



Mike

Do not archive



--

TELEDYNMCS(at)aol.com
Guest

Posted: Tue Jan 27, 2009 4:45 am Post subject: AAE Antennas

In a message dated 1/27/2009 3:06:40 A.M. Eastern Standard Time,  europa-list(at)matronics.com writes:

  	  Quote: 	
		  Most    transponders have a peak power of up to 250 watts not two  

Kilowatts. 	
  

 Hey Tim,

 

You are correct here. I misread the spec's on the data sheet. Peak  power, as listed for my Garmin and for a Narco that I have in another aircraft  is indeed 250 watts as you state. I misread the specifications under the  transmitter portion, but didn't catch that they were speaking  about peak ERP for a particular type of antenna for these  transponders. That's what I get for trying to discuss technical issues before my  morning coffee.

  

 Again, there are indeed a host of other things that are higher on the list  in terms of safety. I wholeheartedly agree. However, I maintain  that unnecessary RF exposure at this power level is not something to  ignore. I have two friends who have sustained serious eye damage, one of  which is legally blind, because they did not heed the  warnings when aiming antennas while attempting to achieve moon bounce  at similar power levels. This eye damage was sustained from brief, but  repeated encounters with the signal radiating from the back  lobe of an antenna where the signal level was some 60 dB  down from the primary lobe. Once your retinas are damaged, that it. I'm not  trying to scare anyone, I just want to make them aware of the  potential danger of repeated, close up exposure to this level of RF. From  my experience most people are not aware that retinas can be damaged from RF  exposure.  I'm very cautious around RF because I work around  it regularly and have for over 20 years. I've seen first hand what it  can do to people. To each his own, I suppose. BTW, the childbearing comment  was meant as a joke, but it is well established that repeated exposure to  RF does indeed reduce sperm count.

  

  As I have said here numerous times before, if you place your  antenna at least two wave lengths away from your person you will  reduce your exposure by 96%. Two wave lengths at 1090 Mhz is, as you  say, about  22" or 60 cm.

  

 Regards,

  

 John  Lawton

Whitwell, TN (TN89)

N245E -  Flying

 A Good Credit Score is 7201028747/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=62%26bcd=DecemailfooterNO62"> See yours in just 2 easy steps!

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