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Topic: Old satellite dish as a parabolic microphone (Read 757 times) previous topic - next topic
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Old satellite dish as a parabolic microphone

Hi everybody.
I know this may seem a strange question but here it comes anyway: is it possible to adapt an old satellite dish to work as a parabolic microphone? In case that makes sense, are there any advices to improve its performance/way to setup it?

Thanks in advance!

P.S. I'm just being curious, I don't really have a planned use case (maybe I could employ it to listen to birds sounds in the countryside).

Re: Old satellite dish as a parabolic microphone

Reply #1
Consumer satellite dishes aren't really geared towards precision. They're build such that pointing the dish vaguely (as in, set using hand tools and just pivoting it on the bracket) is enough to pinpoint the satellite. Also, they're offset antennas so the mirrored area might be somewhat undesirable, as well as not really all that sound reflective. It's OK, for testing, but I'd have a look at constructions of regular sonic mirrors used for this application.

Furthermore the dishes are shaped such that they capture both the horizontal and vertical polarity characteristics of the LNB. Your microphone most likely will have a different characteristic, and hence the antenna might not be the best shape for that. You can get a small satellite dish and hammer it to shape, if you want to do that, though. Sometimes, simpler solutions might be more effective: place a lapel mic in front of a plastic bowl, and you might end up with far better results, as a satellite dish is usually to shallow to converge incoming sound waves into the center. <--- note the much deeper dish shape compared to a satellite dish. Also not the position of the active component of the microphone and the almost spherical shape.

Furthermore, this might interest you:

Re: Old satellite dish as a parabolic microphone

Reply #2
I did exactly that about 20 years ago, but the dish was actually a 3' microwave antenna, so an actual parabolic, not all that deep, probably 7" or so.  The hard part was precisely locating the focal point and putting (and keeping) the mic there.  I made a bracket and used some threaded rod, and adapted a mic clip. When it's off you get secondary lobes, but it actually still works.  The other hard part was aiming it, because it's solid and you can't see what you're doing.  I was going to make a sight tube, just never got to it.  I still have the rig.  It was quite amazing how well it works.  I was able to listen to conversations clearly at about a quarter mile over open water.  Roll off the low end, it's not working down there anyway.

Re: Old satellite dish as a parabolic microphone

Reply #4 <--- this is pretty cool. He made a relatively decent parabolic microphone out of a trash can lid, some duct tape and a lapel mic.

Reflectors made out of thin metal, may be quite prone to pinging.

It is more circular instead of oval and has a shorter focal point.
Well, the ovality of regular satellite dishes is just  so it can be an offset antenna dish. Also, the the focal point in TV satellite dishes is intentionally not a  small focal point, but is elongated, to allow for leeway when aiming the antenna by hand.

TV satellite dishes are offset for two reasons: they have their reflected characteristic pointed upwards so they can be mounted almost flush to a wall, and the back of the relatively large Ku-Band LNB doesn't block part of the signal. Also, this setup allows using two LNBs next to one another.

Re: Old satellite dish as a parabolic microphone

Reply #5
Understood! Thanks everybody for the comments and links.
I'm going to test the dish in my free time to see which kind of results I can get without fiddling too much with it.

P.S. If I recall correctly the one I've got isn't an offset antenna.

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