K7TEJ

The 6m Moxon

Rating: 7 votes, 5.00 average.
Recently I started to look for a winter project and thought, "I rally need to improve my 6m situation". With that in mind I thought I'd look at some sort of 6m beam. I don't remember exactly wn=hen or why the word Moxon came to mind but it did, Thus is born the 6m Moxon project. The more I researched the moxon design the more I found to like. First is simplicity of construction, It's basically a rectangle of wire. then there is size, compared to a yagi the moxon is lot more compact. Then there is the gain. The model I'm making has a 10.83db forward gain and 13db Front to back. the beamwidth is almost 90 degrees as well so you get a lot of gain over a pretty wide swath.

As I started to get serious, I found the following website, which has lots of good info & ideas: http://www.moxonantennaproject.com/index.html

Under the design tab, I found a link to a small program called "MOXgen" which, with a few simple inputs (Design frequency and wire size) spits out the critical dimensions for your antenna. It will also create an EZnec model that you can then play with in EZNEC. I designed mine at 50.2Mhz with #12AWG wire. SWR was resonant @ 50.6 (SWR 1.043), according to the EZnec model.
Support
Now that I had the performance data, how to build it? The most common form of supporting a moxon is two diagonals that support the corners and two insulators that separate the elements at the sides. A common method is to use Carbon fiber fishing poles for the diagonals. I quickly discarded this thinking at the size of a 6m moxon (about 84 inches across by 30 inches deep) there would be significant sag. I settled on an I beam design made of PVC pipe. I gathered the materials and was pleasantly surprised to see the main crossboom did not sag at all, even with the side booms. I used 3/4 inch Sched 40 PVC for the main boom and 1/2 for the side beams (since I had several pieces of that left over from another project)

At the moment I have the boom built and just need need to measure & cut the wire and attach it all. Then figure out how to best mount the feed point & Mast support (I plan on using it at 10 feet, 1/2 wave).

I'm thinking if this works out well, it could be fodder for a club project, we'll see about that.

Anyway I've attached a few pictures of what I've done so far. Let me know what you think.

73 Rick, K7TEJ
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