Loading…
Moxon and hex beams
Compact wire beams with good front-to-back.
Compact wire beams with good front-to-back.
Both are compact two-element wire beams that bend their elements instead of keeping them straight. The Moxon rectangle is a single-band beam shaped like a rectangle with the tips of the two elements bent toward each other. The hex beam nests wire elements for several bands on one frame of spreaders. Each takes a lighter, smaller package than a full-size Yagi and keeps a clean pattern.
A two-element Yagi gets its pattern from a reflector spaced well behind the driven element, and the elements are about half a wavelength wide. Bending the ends of the Moxon's elements toward each other does two things: it shortens the span, and it couples the tips strongly across a small gap. The currents then settle into the phase that cancels radiation to the rear over a wide range of frequencies. You get most of a two-element Yagi's forward gain, roughly 5 to 6 dBi in free space, and a deep rear null.
You cannot guess Moxon dimensions. Width, tail lengths and gap are a set of ratios found by antenna modeling, so build from published or modeled tables for your wire size and band.
A hex beam holds two bent wire elements per band on six fiberglass spreaders radiating from a central hub. The elements for different bands are nested on the same spreaders and share one feed line, so one compact antenna covers many bands. Gain is in the territory of a two-element Yagi, often a little less, and the pattern stays usable across each band. Shapes and claims vary between designs, so compare modeled or measured data rather than advertising.
| Full-size 2-element Yagi | Moxon | Hex beam | |
|---|---|---|---|
| Size | widest | about 70% as wide | compact, round footprint |
| Gain | the most of the three | a little less | similar or a little less |
| Front-to-back | moderate | high | moderate to good |
| Bands | one (or traps) | one | several |
| Weight | boom and aluminum tubing | light wire frame | light, wire on spreaders |
These are typical trends, not guarantees. Wire beams are lighter and need smaller rotators, but they have more parts that can sag, tangle or fail in ice and heavy wind than a rigid aluminum Yagi.