Use existing redundant ELT antenna for PA 1090mhz reception?

[peteD]

PLAN B:
So think I might shorten existing ELT ant to 86mm for pilotaware sig and fit 1090 ant for other...any reason why not?

Also have redundant gps antenna, an AT575-9 is there anyway of using this for pilotaware, either a gps usb with ant connection, or possibly indirect coupling?

http://bytethebullet.com/geocaching/reradiating_antenna.htm

Thanks
Pete

[exfirepro]

Pete,

By my calculations a 1/4 wavelength antenna for 869.5 MHz should be nearer 83mm * - and as it’s a transmitting antenna, this will only work provided it is fitted on a suitable ground plane.

*See explanation here...

http://forum.pilotaware.com/index.php/topic,438.msg11628.html#msg11628

If you don’t get it right you run a high risk of losing a significant proportion of your transmit power, which at 500mW is already pretty low. As you are obviously able to remove the ELT antenna, a better option would be to simply replace it with the standard tuned PAW 869MHz end-fed sleeve dipole from the PAW as high up as possible on a suitable low-loss co-ax extension.

Regards

Peter R

[peteD]

Ah, thanks, the ELT ant is fitted to the metal fuselage so good ground plane.
Any thoughts on utilising the external gps antenna?

[Vic]

Pete

I'd suggest that would be a no-go. GPS antennas generally only look upwards for obvious reasons and often have built in amplifiers powered by a voltage on the centre core of the coax that would be strictly GPS tuned.

[peteD]

Sorry, misunderstanding, I meant for the gps ant. to be used for the gps, either as per webpage quoted, or directly to a gps dongle with ext. Ant. connection.

[exfirepro]

Hi again Pete,

I did realise that’s what you meant, and did have a look at the spec for your redundant GPS antenna. It seems to be a fairly straightforward (though expensive) piece of kit, so I can see why you’d like to use it. You’d need to find a gps module compatible with your external antenna, with a ‘separate antenna’ connection, and which is also compatible with the PilotAware software. Unfortunately I can’t help you with that one I’m afraid. Anyone else got any ideas?

Regards

Peter R