lynx NGT 9000+ directional antenna installation

[rvmv]

Hoping to hear from someone that has installed a NGT 9000+ (active traffic) in an RV.

Reading through the install specs for the directional antenna it states:

"The mounting site should be on the top forward fuselage, as close to the centerline as possible, and within -10? forward pitch of the in-flight horizon.
The optimum mounting point for maximum coverage is as far forward as possible without exceeding the -10? forward pitch."

With our bubble canopies the most forward top position would be right behind the baggage window which has a negative slope to the rear.

The only way I can figure to level it would be to construct a ramp for it to sit on riveted to the top skin. Would this type of arrangement mess up the antenna's ground plane? Thanks

[Canadian_JOY]

The installation instructions were written by a human and thus are subject to that one person's unique perspective. We all know our individual perspectives are shaped by our experiences. The writer of the installation instructions likely didn't have an RV in mind when writing the instructions. Rather he may have had something more like a cabin-class airplane in mind. Think of airplanes like Beech, Piper, Mooney and larger, with metal cabin roofs.

With this paradigm in mind, the installation instructions are really trying to tell you that, if you have one of those cabin-class airplanes, don't mount the antenna right above the windshield, below the top of the cabin's curvature so the base of the antenna is tilted in a strong nose-down attitude. The radiation pattern of the antenna in such a "tilted" installation would create a large blind spot behind the aircraft.

For a tipper RV I would recommend installing the antenna immediately forward of the windshield if you can fit it there. In fact that same location would work for a slider. Yes, the centre bar of the windshield frame will provide some shadowing directly aft of the aircraft. The natural nose-up attitude of the aircraft will result in the airframe aft of the seats providing shadowing in the aft direction only at low relative target elevation angles.

The bottom line is that, without a hard cabin roof where a ground plane can be established, the RV's and their bubble canopies are going to be a compromise installation. Work out your installation so as to minimize the compromise by maximizing the antenna's view of the sky down to the horizon in all directions.

[rvmv]

Thanks for your reply. I was thinking that the mounting attitude of the antenna may play a role in how the instrument interpreted the location and direction of the surrounding traffic.

[GregM]

You might want to contact their tech support and ask if the directional antenna can be mounted to the bottom of the aircraft. I have installed two of these units at work on our helicopters and the directional antenna is mounted on the bottom. I don?t know if the platform makes a difference.

[rvmv]

I did some more reading and found:

"The directional antenna can be bottom mounted only if a suitable top mount location is not available. Each bottom mount installation must be evaluated on a case-by-case basis. Before starting a bottom mount installation, contact Field Service Engineering at 1-800-453-0288 or 1-616-949-6600."

I gave them a call and left a message. I'll post what they say when they call back

[Canadian_JOY]

This will be very helpful information to know - thanks for continuing to share.

[rvmv]

Just got through talking with a very helpful field service engineer from Lynx. He recommended top mounting just aft of the baggage window. He said they had some cessna mountings that were similar with good results. He also said the instructions for mounting were purely for maximum sky coverage and would not affect the way the instrument processed the data received. He also mentioned that if the fuselage was curved preventing close adaptation of the antenna to the skin that they had various mounting plates that would take care of the radius.

Thanks to all that replied! rvmv

[Canadian_JOY]

Thanks for the follow-up - good info to know.