DG7YBN 5el Yagi antenna for 23cm (1296 MHz)
Description
This is a 5-element yagi antenna for 23cm band designed by DG7YBN, as described on http://dg7ybn.de/1296MHz/YBN23_5m.htm . Printed with Ender 3 Pro, 0.2 mm layer, 0.4mm nozzle, supports enabled. Elements are made of 3.2mm aluminium TIG welding rods, radiator (dipole) is made of solid copper wire, ~2mm thick. Elements are thinner than in the original design, so I made each of them about 2mm longer. This was verified with 4nec2 simulation. Positions on boom did not change. Use calipers and a file to make sure elements are cut to the right dimensions. Sub-mm precision is required. Antenna is fed using a short run of UT-141 semi rigid coaxial cable, but any 50-ohm thin coax suitable for GHz bands should do fine. Male SMA plug is mounted on the other end. In order to make the radiator, solder copper wire directly to tinned coax shield and center conductor. Cut the arms longer, and then, after mounting all the elements, shorten arms using pliers to obtain desired resonance frequency. 1.8mm dia copper wire resulted in ~113,5 mm end-to-end dipole length. A NanoVNA v2 or other antenna analyser working on 23cm helps a lot. Secure dipole & coax in place using glue (CA + hot glue) and heat shrink tubing. By making the elements longer, the resonance frequency goes down, which is desired if the antenna is to be used with repeaters using -28 MHz shift, as it'll have to TX on 1270 MHz with reasonable SWR. SWR of about 1.5:1 is achievable in 1270-1300 MHz range. This is a field-proven antenna design, exhibiting a very good directivity and gain. It allows to easily hold a conversation via the repeater, from a location where stock HT antenna was barely able to turn the repeater on.
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