DL7AOS' 20 METER MOXON
The short video of this antenna at Youtube:I was looking for a simple gain antenna for portable field day style contest use when I stumbled into the moxon beam. My first try was a 10m version using an old TV antenna boom and some PVC pipe as spreaders. This one works like a charm and assembles in less than 10 min.
My next project is this 20m moxon. Again I opted for the boom version feeling this is more robust than the spider one. The boom is made of 25 x 25 mm aluminum box shape material. Kind of a double boom construction makes mast-to-boom clamping very easy using two muffler like clamps. The spreaders are made of very cheap fishing poles. Make sure they are made of pure fiberglass, no carbon allowed here. Mine are called Silverman Stigma Pole.
The spreaders are fixed with simple cable ties, I used the UV-resistant and re-usable type. For permanent installation use stainless steel worm clamps instead. Aluminum angle stock of 1 m length is used, directly bolted to the boom. At the feedpoint there is a coax balun, just a few turns wound on a round plastic body.
Element length were calculated with MoxGen, resonance on the first try was a little below 14 MHz, but this was an easy fix. The beam worked really fine in the last Russian DX contest, with good gain and front-to-back installed on a 12 m push-up mast. Best part: It even survived some snow storms during the last days with wind speeds up to 100 km/h.
73's Stefan, DL7AOS
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