biquad UHF antenna by ve7it

Last crawled date: 3 years ago

This project provides a mounting post used to hold UHF bi-quad antenna at a fixed distance from a reflector screen. The screen is a recycled wire fridge shelf. Bi-quads are cheap, easy to build and very good performers. Antenna gain is about 10-12dB. My reflector is a little bit small, but it was available. The bi-quad SWR is affected by how close the antenna element is to the reflector screen. You can build this antenna without the mounting post and move the antenna around to get the spacing for the lowest SWR. My antenna used #9 enamelled copper wire from a motor rewind shop. Each side of the quad is measured at 168mm which is 1/4 wavelength in the middle of the 440-450 FM band in North America. I used a chassis mount N connector to mount the 1 piece wire element. The feed line and coax connector pass through the centre of the support. If used outdoors, you should protect the mount from UV and moisture by painting it. ABS or petg maybe a better material for outdoor use. The N connector may be fastened to the top of the mount with 2 #4 self tapping sheet metal screws. There are also clearance holes for 4 #4 screws in the base to assist with fastening the mount to the screen. The design uses a modular parametric approach. It is very easy to adjust the settings to accommodate different racks, connectors, and fastening ideas.