Disguise Antenna.pdf

A horizontal "slot" antenna cut into the reflector of a TV dish provides high performance while being disguised. The antenna is made by cutting a 39-inch long slot into the reflector of a SlimLine DIRECTV satellite dish. The slot antenna behaves like a dipole, with roughly 2 dBi gain and omni-directional radiation pattern.

Key Features:

The width of the slot determines its bandwidth, with narrower slots having less bandwidth.
A horizontal slot is vertically polarized, making it suitable for 2 meter repeaters.
The dish size and slot size are important, with a larger surface area providing better performance.
The slot can be cut using a jig saw and metal-cutting blade, with the edges filed smooth and protected with clear plastic spray paint.

Construction:

Remove the reflector from the mount and LNB assembly.
Mark a straight 24-inch horizontal line and two 7.5-inch drooped ends on the back of the reflector.
Cut the slot using a jig saw and metal-cutting blade.
File the edges smooth and apply clear plastic spray paint for rust prevention.
Attach a rigid plastic brace across the slot for stability.

Feeding and Matching:

Attach the feed coax braid to one side of the slot and the center conductor to the other directly across, but not in the middle.
Use a 1:1 current balun to match the antenna.
The feed point location is not critical, with a good match achievable anywhere 3 to 6 inches from the end of the slot.

Performance:

The antenna has a bandwidth of less than 1.5 to 1 SWR over the entire 2 meter band.
The gain is roughly 2 dBi, with a vertically polarized radiation pattern.
* The antenna is suitable for use as a 2 meter base station antenna, with good performance and low visibility.