The Moxon Beam Antenna

The Moxon Beam, introduced by L. Moxon (G6XN), is a compact 2-element Yagi featuring a radiator and reflector with reduced dimensions, approximately 75% the size of a full-size beam. This design utilizes bent element ends for capacitive loading, which is superior to inductive loading with coils, resulting in greater bandwidth and lower losses. DK7ZB details that while the gain is slightly lower (0.5-0.7 dB) than a full-size beam, the Moxon offers an exceptional front-to-back (F/B) ratio of 30 dB or more on its design frequency, surpassing other 2-element beams. The article provides specific dimensions for building wire Moxon antennas for bands from 30m down to 10m, and also mentions a 2-m-Moxon.

Construction guidance includes using fishing rods for lightweight spreaders and an aluminum tubing spider for support. The resource highlights the utility of Moxgen by AC6LA, a freeware program that simplifies Moxon beam design and generates EZNEC output files for further analysis and tapering modifications. DK7ZB emphasizes that the design frequency should be set at approximately one-third from the band's beginning to optimize SWR performance, as SWR tends to rise more significantly below the design frequency. The bandwidth for SWR < 1.5 is noted as sufficient for ranges like 28.0-28.7 MHz and 21.0-21.45 MHz when constructed with aluminum tubes, though wire beams exhibit a narrower bandwidth.