70cm Halo Antenna

thingiverse

Join in the UHF SSB Fun! This horizontally polarized omnidirectional antenna can be installed as a single loop or in a stack with the proper phasing harness setup. It is designed to fit into a piece of 1" PVC tubing and the loop should be parallel to the ground, with clear Rustoleum leak seal or similar gooped onto all dissimilar metal junctions and interfaces where water is a big no no. 70cm 432.1Mhz Single Sideband Antenna 13 - 11/16" length of copper tubing (hint, to measure the length of curled tube, use a section of wire or rope with a large enough diameter to fill the entire tube, mark with a tape flag or sharpie, then straighten it against a ruler) Use a tapered clay flower pot to slowly bend the copper into a loop with a 1" gap at the end. Make sure the loop is flat (planar), too. Mark the center of the loop with the use of polar graph paper, and make a small hole. Solder in a small section of solder wick, wire, or small coax braid for the ground connection to the body of the 'N' connector. Gamma match is 3" of tubing and 3" of RG-58 center conductor. I had to also use the metal braid over the conductor inside of the tubing as the air gap was too large IE not enough capacitance to reach 432.1Mhz. If you can't tune LOW enough, either lengthen the overlap area or add the braid in to make the gap between the tube and the wire effectively smaller. I used a small coffee cup and a tapered pizza parlor style cup to place the curve onto the gamma match tubing. Gamma brackets use 2.5mm hardware, the rest uses 3mm. Use an 'N' box mount flange connector. See photos for process!