Ground Plane Experiment 1

This is my first home brew ground plane antenna experiment. I attempted to design it for the 2 meter band. First, I purchased 2 of those aluminum throw away cake pans from the dollar store. I cut off the edges so I would only have the bottom. Then I folded it in half, then in half again, and again until it was firm enough (or so I though) to provide a good base for attaching my wires. I also cut holes for my antenna in the center, and 8 others around the edges of the aluminum sheet for attaching my ground wires.

Then I grabbed some wire coat hangers. I cut 8 of them to 24 inches for the ground plane wires. For the actual antenna I cut one to about 21 inches. I used a plastic PVC pipe to mount the entire thing on, so i could tie it to the railing of my balcony. (Apartment living has some down sides at times) I used a rubber gromet on the radiating portion of the antenna to insulate it from the aluminum sheet, then used electrical tape to hold it in place.

I left about 2 inches of the bottom of the antenna so i could bend it into a loop and have it stick out of a hole in the PVC pipe. This is for attaching the coax. I attached my ground wires by bending the ends through, and using needle nose pliers to secure them. Once finished, this wasn't very secure, and the aluminum began to bend. However, since this is an experiment, I decided to press onward. I took some 22 gauge copper wire and looped it around each eyelet of the ground plane wires, then secured all of it with electrical tape. I left some of the copper wire hanging out of the tape to attach the coax shielding.

The aluminum sheet i attached to the PVC using a combination of super glue and electrical tape. Once finished, I wasn't really impressed with this as it doesn't seem very sturdy. Then I attached the coax, and wound a tight coil around the PVC to form a quick n dirty 1:1 balun, securing it with electrical tape.

I took the horrid contraption outside for a test. To my dismay, it was horrible. It became resonant at 147.5MHz and above. Not quite what I had in mind. I tried taking a piece of copper wire and taping it to the radiating element, as well as to the ground plane elements to lower the resonant frequency. Nothing changed. I tried trimming the radiating element as well as the ground plane wires. Still nothing. In fact, it didn't matter what I did, it always stayed resonant at the same frequency range and above! This is extremely odd for an antenna. This was quickly turning into a scientific mystery, so I decided to trim the entire thing in short. Still, the resonant frequency did not change. So I dismantled it and brought it backcredibly inside. Back to the drawing board.

I suspect my problem arises from the fact that my feed point i about an inch below the ground plane. Perhaps only the lower half (below the antenna) was acting as a radiator? In any case, it calls for a complete redesign and rethinking of the antenna.

Notes: As I have limited funds, and limited equipment, I had to solely rely on the S meter on my HT. The test were performed using only 4 Watts of power to prevent harmful RF issues as well as damaging the equipment.