Need advice on ADS-B OUT antenna - iFly General Discussions

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Need advice on ADS-B OUT antenna

3/6/2017 8:40 PM

PA-22

Joined: 2/16/2011

Posts: 501

Need advice on ADS-B OUT antenna Modified By PA-22 on 3/6/2017 9:56:33 PM

I am looking for some advice from any antenna engineer who may be lurking out there on the Forum. The FreeFlight Rangr Lite installation manual states the stick & ball ADS-B OUT/IN antenna must be placed at least 6 feet away from any ADF sense antenna. I am short on ground plane real estate on my airplane's belly, where my ADF integrated sense/loop teardrop antenna is mounted. So here is my question for someone who knows the alchemy of antennas: Would it be permissible to place the ADS-B antenna in close proximity to a Honeywell/Bendix/King KA-42B integrated sense/loop ADF antenna as long as they are not operated simultaneously? Or is there risk that even with the ADF switched OFF, the ADS-B could/would induce harmonics into the sense/loop teardrop antenna and distort the ADS-B signal in some way? Thanks for any technical advice. ==== Ralph

3/7/2017 7:00 PM

ErgonomicMike

Joined: 9/3/2014

Posts: 2102

Re: Need advice on ADS-B OUT antenna Modified By ErgonomicMike on 3/7/2017 10:35:19 PM

I designed the ADF loop/sense antenna for Cessna's ARC when we were trying to catch up to King.

The answer to your question is: Yes, you can mount them close. The reason they wanted the Out antenna mounted far away is because it will burp RF into the ADF.

On our Glasair, I mounted our ADF antenna on the top of a ground plane, with the xpndr and DME antennas on the bottom of a different ground plane. I don't have 6 feet of separation, and I get a bit of brr... brap into the ADF. Otherwise, it works okay.

3/7/2017 9:31 PM

PA-22

Joined: 2/16/2011

Posts: 501

Re: Need advice on ADS-B OUT antenna

Thanks, Mike. Appreciate your response. That's what I was hoping the situation would be. Regards. =====Ralph

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