Tracking a radio signal

[Jeff Pahl]

Originally Posted by Jared341

Although the phase-based approach that Don posted is simpler to implement and somewhat more robust to multipath, this approach would work with an omnidirectional antenna and a well-designed slit (which is admittedly hard to make).

I just want to point out, though, that there is no need for a slit if you use a directional antenna. Simply rotate the antenna; the antenna's azimuth at the peak magnitude response in a revolution should correspond to roughly the right heading. Your accuracy would be limited by the "sharpness" of the antenna's response curve, however.

At 433 MHz, to attempt to rotate a directional antenna you would end up with something that looks like an AWACS. The antenna length would be a significant percentage of your wingspan to get any sort of a reasonably narrow beamwidth.

A slit is also going to have a very wide beamwidth.

As Don suggested, a doppler system it probably going to give you your best results. It also has no moving parts, so your reliability will be higher and you will not have any issues with the rotating mass affecting the flying.

Do multiple beacons transmit at the same time? That will be a problem, as due to the capture effect you will only hear the loudest beacon, which may not be the one you want. If they transmit one at a time, then you can listen for the id of the beacon you want.