biquad UHF antenna

thingiverse

This project offers a sturdy mounting post designed to securely hold UHF bi-quad antennas at a precise distance from a reflector screen crafted from recycled wire fridge shelves. Bi-quads are renowned for being affordable, simple to build, and highly effective performers with an antenna gain of approximately 10-12 dB. Although my current reflector is slightly smaller than ideal, it was readily available, allowing me to proceed with the project. The bi-quad SWR is directly influenced by the distance between the antenna element and the reflector screen. If desired, you can assemble this antenna without the mounting post and manually adjust the spacing to achieve the lowest possible SWR. I utilized #9 enamelled copper wire sourced from a motor rewind shop for my bi-quad construction. Each side of the quad measures 168mm, equivalent to one-quarter wavelength in the middle frequency range of the 440-450 FM band in North America. A chassis mount N connector was employed to attach the single piece wire element. The feed line and coax connector pass through the centre of the support for added stability. When used outdoors, it is crucial to protect the mounting post from UV radiation and moisture by applying a coat of paint; ABS or PETG may be more suitable materials for outdoor applications. Two #4 self-tapping sheet metal screws can secure the N connector to the top of the mount, while four clearance holes in the base facilitate fastening the mount to the screen using #4 screws. This design benefits from a modular parametric approach, allowing users to easily adjust settings to accommodate various racks, connectors, and fastening configurations.