Homebrew: Parabolic Microphone

I’ve set out to build a portable parabolic microphone. I plan to build one with a budget of less than $10 and with any luck I can drop that down to less than $5 by using spare junk laying around here. My goal is to have it work at least as well as those you’d pay 300+ dollars for from a retail business. However, since I haven’t the funding to purchase a ready-made unit for direct comparison, nor do I know of anyone that owns one that I can borrow, I will have to find a way of making some sort of indirect comparisons that aren't completely devoid of useful information.

Several years ago I built a Ten-Tec Hi-Sensitivity Audio Amplifier Kit (part #1252) which I plan to use for amplifying the sounds picked up from the parabolic microphone, but since I use this for multiple applications, I did not figure it’s price into the above cost estimate. Had I needed to use a built-in amplification circuit for the parabolic microphone, I would either add about $10 to the estimate for the parts to build a simple unit myself, or add on the cost of an audio amplifier kit such as the Ten-Tec Utility Audio Amplifier (part #1550) which is currently selling for $15 + shipping.

Can I succeed? I don’t know, but it will be fun trying. There’ll be more to come later on (with pictures!) when I actually get up the gumption to begin working on it.