Hattenna SWR.jpg

This is a very simple 1/4 wave ground plane antenna. It's mounted on a cheap baseball cap using a zip-tie. I wanted something simple to use at swaps to get the antenna up in the clear and away from the body. Looks weird but works very well. The SWR is low enough the antenna is usable over the entire Ham 70cm band and up through GMRS.

The antenna is built using a BNC PCB male socket with thick bus wire soldered on for the ground plane. The vertical section is thinner wire. The wire elements are only about 6 inches long making this ideal for a compact antenna. A 90 degree BNC male to BNC female adapter is screwed onto the bottom of the socket. I used a short cable with BNC male to SMA adapters to connect to the antenna and radio. The radio was kept on the belt and used with a speaker microphone.

The antenna was modeled using EZNEC V7.

https://www.eznec.com/

The tested results are very close to the model. The measured SWR is a bit lower due to the slight attenuation in the 3 foot jumper cable.

The radio I used was an Kenwood NX-1300DUK5 set at 1 watt, low power, using DMR. That kept the effective power to around 0.5 watts due to the nature of DMR, TDMA, modulation. With the error correction I had clear copy just about everywhere. I used this while at the annual Hamvention held in May.