Transponder antenna can fry your dangly bits

[Spodman]

From THE CANARD PUSHER NO. 30 Oct 81

 

The transponder antenna can be mounted under the front seat thigh

support, and this is where quite a lot of builders have located it,

however, Jim Weir of Radio Systems Technology has cautioned that it may

be possible that high powered microwave energy may be radiating in very

close proximity to a rather sensitive part of the pilots anatomy. To

put it bluntly, it may be a little like sticking your fanny into a

microwave oven! In any event, no qualified person to our knowledge has

tested this, so it may be prudent to laminate a sheet of aluminum foil

under the thigh support. Microwave energy will not penetrate the

thinnest of metallic foils.

 

I think I remember a thread about this but can't find it. Where do you put the tspr antenna? Is there a problem with including Al foil under the paint?

[Marc Zeitlin]

I think I remember a thread about this but can't find it. Where do you put the tspr antenna? Is there a problem with including Al foil under the paint?

Even Jim Weir has long since decided (after some analysis) that this is an old wive's tale at best, and there is NO evidence that normal transponder energies can be dangerous.

 

My antenna is up in the nose in front of the rudder pedals, facing downward. Works great. I used 1/32" aluminum as the ground plane.

[Spodman]

Fairy Nuff. Sorry to be spreading old wive's tails...

 

While I didn't find anything relevant in a search the "similar posts" thingie down below did. Shame it doesn't appear until I've asked a question for the nth time

[longez360]

Reminds me of the "turn your cell phones off at gas pumps. It can cause explosions!" dribble... There's a reason why (in places that have caught up) they removed the catch that allows hands-free pumping of gas into yuor car - so you have to pump it, without being able to slide back into the car while it's pumping and cause static discharge. . .

 

I have a Bill Butters, all internal XPDR antenna in my strake and it works extremely well. Don't be misled by avionics companies, and foam core dielectrics. The antenna does not need to be in the free airstream. This system works very well.

[longez360]

Reminds me of the "turn your cell phones off at gas pumps. It can cause explosions!" dribble... There's a reason why (in places that have caught up) they removed the catch that allows hands-free pumping of gas into your car - so you have to pump it, without being able to slide back into the car while it's pumping and cause static discharge. . .

 

I have a Bill Butters, all internal XPDR antenna in my strake and it works extremely well. Don't be misled by avionics companies, and foam core dielectrics. The antenna does not need to be in the free airstream. This system works very well.

[argoldman]

From THE CANARD PUSHER NO. 30 Oct 81

 

 

I think I remember a thread about this but can't find it. Where do you put the tspr antenna? Is there a problem with including Al foil under the paint?

The transponder antenna will need a ground plane at its base (the top-- the antenna faces down) this must be approximately 6" in diameter. (not sure of the exact minimum diameter). A suggestion would be to extend it so that your buns or other appendages are shielded by it from the tip of the antenna.

 

This may alleviate the problem of well done meat.

[cncdoc]

If focused and with enough power, your "bits" may get sterilized, but you would have to do it on purpose.

 

I would worry more about connections and antenna wavelength errors which will fry your transponder's "dangly bits":irked: