A light rigid structure (of aluminum or other material) which reflects sound to a focus at which a MICROPHONE is placed. This focussing effect is very strong with WAVELENGTHs less than the aperture of ...

To me, this means a large parabolic reflector, a feed horn made of brass sheet, coat hanger wire, and at least for the initial experiments, an RTL-SDR dongle. I’ve done the calculations ...

there’s nothing like cooking hot dogs and roasting marshmallows with a nice parabolic reflector. Of course covering an old satellite dish with mylar or aluminum tape doesn’t take much skill ...