how to connect 2 AM loop antennas at the same time

[wenzeslaus]

I have more or less mastered the arcane art of making an AM loop antenna. typically I don't use an inductance loop and wire it directly to the radio with the variable capacitor (VC) in series with the POS (red) jack and one lead from the loop, with the other lead going to the GND (black) jack.

it seems there is no way to improve the signal strength aside from optimizing the wire spacing, number of turns, and of course making the cross-sectional bigger (a bigger frame). that leads me to think that, for a particular size of antenna, the answer is to use multiples of the same loop antenna connected together.

I tried these and none of them worked:

- 2 identical loops on the same frame, wound in opposite directions, connect 1 wire from each to a VC and the others to the radio, like a C.Crane Twin Coil ferrite bar. could not get it to work. cancelled each other out, got 1 S-unit where either one by itself (as normal) got 4.

- 2 identical loops on same frame, wound in same direction, connected to VC and radio in parallel. required twice the capacitance. poor reception.

- 2 identical loops on same frame, wound in same direction, connected to radio in parallel, each with its own VC. had to tune each seperately to the same frequency. functionally it was big loop divided in two. signal somewhat degraded.

how can you connect 2 loop antennas at the same time?

if it doesn't require multiple VC's I would probably try for several loops in operation at the same time.

 

[EAFrizzle]

What it looks like to me is that you have made is a radio version of a humbucker guitar pickup. It's designed to get rid of 50/60 Hz hum from the electrical mains, so it'll probably choke RF effectively. Try series winding on separate frames, both windings in the same direction, with just the one VC. This should also allow you to orient one horizontally and the other vertically, as an experiment.

 

[RFI-EMI-GUY]

You would have to electrically isolate each loop using a pair of preamplifier stages so that the resonant frequency is not altered. having done so, the orientation would create gain or subtraction and pattern distortion. You could place them outside with equal length feedlines and attain some added gain over fading.

 

[MUTNAV]

Would a combiner / splitter help? Something that could isolate the inputs from each loop and keep the signal from going to the other loop? RFI-EMI GUY mentions preamps, which would work, but if you want passive, then maybe the combiner / splitter arrangement. or maybe several directional couplers?

Thanks
Joel