GNX 375 antenna spacing

I don't own one yet, but I'm planning on purchasing a GNX 375. I'm in the middle of plumbing the RG wire for antennas on the belly of my -8. I searched for the installation manual and now joy. Here is my question: What is the spacing required between the Txpdr and the ADSB antenna on the GNX 375? or can they be the same antenna? or is there a combined blade antenna?

Thx!

Same antenna, so no spacing issues. I was told a blade antenna in the L-band is what you want to use given the option for a 375. But I use a ball and stick optimzed for 978 Mhz for my Stratux 'in' solution and recieve 1090 Mhz all day long, so there seems to be some wiggle room.

PS I have your Avatar hanging as a banner in my hangar, Legacy Hornets Rock!

Gtx 375

I don?t know if there is a combo blade antenna but. The requirements are 2ft from transponder to transponder antenatal, and 2ft separation betwen ads antena and transponder antena. Adsb antena must also be min. 2ftfrom transponder.
Hope this helps.

375 GPS/Xpdr incudes ADS-B In/Out, same antenna, use the blade for best performance.

bbsdad said:

I don?t know if there is a combo blade antenna but. The requirements are 2ft from transponder to transponder antenatal, and 2ft separation betwen ads antena and transponder antena. Adsb antena must also be min. 2ftfrom transponder.
Hope this helps.

Click to expand...

2nd that spacing requirement. I have the Dynon ADSB-472 and the Dynon XPNDR-261 transponder. and when I installed the ADSB-472 antenna, Dynon called for 24in spacing to any 1090 MHZ transponder antenna. (page 14-7 of the current installation manual).

I used a deltapop blade antenna and it looks/works great.
http://www.deltapopaviation.com/UAT_Antenna.html

off the IM:
6.4.1 Antenna Location
The GPS antenna should:
1. Be installed as near to level as possible with respect to the normal cruise flight attitude of the aircraft.
2. Be installed in a location to minimize the effects of airframe shadowing during typical maneuvers.
3. Be installed a minimum of two feet from any VHF COM antenna or any other antenna which may emit harmonic interference at the L1 frequency of 1575.42 MHz.
4. Be installed a minimum of two feet from any antennas emitting more than 25 watts.
5. Be installed a minimum of nine inches (center to center) from other antennas, including passive antennas such as another GPS or XM antenna.
6. Be installed a minimum of three inches from the windscreen.
7. Have a twelve inch center to center spacing between GPS antennas.

and:
6.5 Transponder Antenna Installation
Ground planes must be considered for installations on composite aircraft. Conductive wire mesh, radials, or thin aluminum sheets embedded in the composite material supply the ground plane to maximize the antenna pattern (gain). This can improve transponder performance.
The antenna mounting must use the aircraft manufacturer?s type certificated antenna location and style. The antenna must be installed in accordance with manufacturer instructions and/or AC 43.12-2A chapter 3.
Transponder antenna considerations help the installer to select the best location for the antenna. The antenna should:
1. Attach away from major protrusions, such as engines, nacelles, propellers, and antenna masts.
2. Mount as far as practical from landing gear doors, access doors, or other openings that could affect its radiation pattern.
3. Vertically attach on the bottom of the aircraft.
4. Not attach within three feet of the ADF sense antenna or any other communication antenna.
5. Not attach within six feet of a DME antenna.
6. Attach a minimum of three feet from the unit to prevent RF interference.