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Antenna placement and interference

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autoreply

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Joined
Jul 7, 2009
Messages
10,824
Location
Rotterdam, Netherlands
I'm thinking about antenna placement, interference and all that stuff.

I don't want any "stuff", hanging out in the breeze. Yes, aerodynamic efficiency is an issue ;)

I've a design that's pretty similar to a glider. Downwards fin and pusherprop, mid-engine. Construction is composite, so the lowly-loaded parts can be replaced with glass or kevlar (those are transparant for radiation).

I have 5 places "available" for antennas. On top of the instrument panel, behind the headrest for the pilot, in the wingtips (preferably not, detachable wings so that would require connectors), on the lower side of the nose (the whole canopy and the lower part of the fuselage front cover slide forward) and in the fin (would required kevlar/glass spar).

Just thinking about all possible antennas that would require placing. I'm especially curious about interference.

Here's a good source for all frequencies:
Frequency Allocations


GPS: 1200-1600 MHz
*On top (instrument pane or behind headrest). Small antenna (3X5X1")

COM, 100+ MHz
*Conventional ones are pretty tall (19", vertically polarized) Possible mounting in the fin. There are also "tape-like" antennas, but they have to be mounted in a non-carbon structure. Possibly in the nose cone or fin.

NAV + ILS: 100+ and 330 MHz
*Same problems as above, 19", horizontally polarized. Is typically the NAV/COM antenna used? How about the 330 MHz antanna?

ELT: 400 MHz?
*On top? Crash-resistant location (below headrest?) Far from COM

Transponder: 1000 MHz
*"All-round" visibility, front and slightly downwards have priority. Lower part of the nose? How about interference with NAV/COM?

ADF: 0.1-2MHz
*Obscure, don't need it I guess?

Magnetometer (EFIS).
*Quite sensitive for antennas. Necessary to keep away from direct current, being landing lights and generators-alternators. Batteries might also be a problem.


Any comments on placement? How about interference between the above antennas?
 
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