Horn type directional microphone

Hi all, I was just thinking about an article I read some time ago, I don't remember if it was online or in print. Basically the project consisted of a square shaped tapered horn (like some early radar devices) the "mouth" was about a foot square the thing then tapered down to about a 3" square, this end is where the microphone went. Anybody remember this article?, does anyone have a copy?

Searched my files but all I came up with are these cool earphones

Spy microphones for children use a parabolic dish to focus sounds to a microphone. Pros use a "shotgun microphone".

Leftyretro, I want to buy those ear buds for my mp3 player