Do shark fin style transponder antennas have a ground plane minimum for proper operation? I'm considering mounting mine in the tail near the horizontal stabilizer on the bottom of my RV 10.
I'd simply suggest you consider the likelihood and consequences of an over-rotation/excessive flare. In such a circumstance, damage to the tiedown ring might be preferable than having to replace a transponder antenna....
Tiedown ring: $5
Sharkfin Antenna: $140 or more
Extra RG-142 or RG-400 coax to get the signal back further to the antenna: $4.20 per foot.
Yeah, I'd recommend putting the transponder antenna no further aft on the belly than just behind the rear baggage bulkhead... roughly under the place where most RV-10 builders put the battery.
I am mounting my transponder headunit in the tail by the battery. I was considering mounting the antenna that far back as the ADS-B antenna is near the battery and they need to be 5' apart. So that would either mean running cable from the head unit in the tail up towards the firewall or running it back to the tail area.
Having the box in the rear makes my response different then. I would install it 12" or so in front of tail tiedown so that tiedown would make contact before blade antenna in an unusually nose high attitude. My whiskers are in that spot. Should have put it on top of vs, which I guess is where yours is.
That's roughly where I am thinking of putting it. I do not have wiskers - I am going GPS only, any place with a ILS approach has a GPS approach. That leaves only the random place with a Localizer only and hasnt gotten a GPS or GPS overlay approach.
Not worried about the end of the world terrorist scenario of lost GPS or solar flares. Ground based Nav is dying, I for one am not building that in.
"Ground based Nav is dying, I for one am not building that in."
You have a point, but we're not there yet. A couple of months ago I took an IFR student on his x/c. We had planned on the GPS approach at KCIC, but it ONLY took us down to 300' agl and required 3/4 mile vis. When the wx dropped to 200 and 1/2, we needed and were glad to have on-board the ILS equipment.
