Moxon Rectangle Antennas - Lighter and better than Yagi

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Grzyadms4x4
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Moxon Rectangle Antennas - Lighter and better than Yagi

Postby Grzyadms4x4 » Tue May 19, 2009 3:00 am

After I made my super duper collapsable folding/flexible yagi, I thought to my self, "self, this is great, but there's a lot of parts. Is there something better?". And the answer is yes. Introducing the Moxon Rectangle, you've probably seen them before, except mine isn't as pretty as the mass marketed ones. One thing mine is though is cheaper. I am no whiz about antennas, but this is pretty easy and at the bottom of the page are link to the moxon design program and 3-d modeler/field viewer which shows you in what directions the antenna picks up the best(forward gain).

moxoninhand.jpg


Yagi's are great, they are very directional and reliable, just a little big. The Moxon Rectangle will, on average,outperform a yagi's f/b ratio and forward gain(directionality). As you can see below there aren't many pieces, and when compare to my standard 3 solid element yagi, which is made by Cushcraft and is really good, the Moxon did better. IF you aren't pointing at that collar, you won't get a signal. I made it with a pices of plexiglass as these antenna elements MUST be insulated from the boom and each other.

The other good thing abut these is they almost never need any matching system. The design and method in which a Moxon Rectangle work make for almost a perfect impedence match between the antenna and receiver.

I used 3/32" "music wire" from Ace for the elements as they are stiff but very flexible with little memory. I measured the lengths and bent it all to specs. I then "precisely" measured and cut in the middle of both elements, so that I can make the antenna fold. I then inserted the long ends of the elements into the holes to one side of the allen bolt and tightened them down.(See Below)

I used lugs from air conditioner contactors to make swivels so that the antenna would fold.

lugs.jpg


I then used washers under the tabs where the mounting holes of the lugs are to fix the uneven mounting that would have resulted without them.

reflector detail.jpg


The rear or reflector element must, when opened be essentially a solid wire with no break in it. I was able to do this by mounting the two lugs for the two rear pieces of the reflector very closer together. So close that the washers underneath the lugs touched an completed the circuit. This way it still is a solid element. The forward most element or driven element as it's called should and must be separated. I measured and cut it just like the rear, except I mounted the two lugs about 1/4" apart to electrically insulate them from each other. These two lugs are also where the RG8 cable connects to.

feedpointelementgap.jpg


Then just cut your antenna wire attach the inner and outer wires to two ring electrical connectors to attach you feed line. I also would recommend some extra washers on both sides of the feed line ring connectors to keep the connectors from binding when swiveling the antenna elements.

This antenna seriously rocks! It is way better than my 3 element yagi and probably better than my 4 element. It has a very large null on the back end, so all I pick up is my collars when the antenna is pointed in the right direction. There is also almost no side pickup when rotating the antenna. Here's the CATCH! The antenna must be as close to a rectangle as possible and the ends of the l's on the elements must stay as close to design specs as possible. Which really isn't that hard, if an element bends, bend it back.

I will post some more pics this week as well as pictures of the reception field compared to a yagi or similar.

Links:

http://www.moxonantennaproject.com/design.htm - Easy moxon rectangle generator.
http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=6997 - The best antenna field viewer, optimizer and builder. Plus its FREE.

Here is a screen capture of an antenna modeled for 216.5 mhz which should work fine for 216, 217, 218, 219 or use the software above to get the EXACT measurements for the collars you are using.
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Re: Moxon Rectangle Antennas - Lighter and better than Yagi

Postby livetohunt » Tue May 19, 2009 3:13 am

Looks great wish I would have seen this before I bought mine I would have loved to make one. But I did find mine on ebay for around $30-$35.
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Re: Moxon Rectangle Antennas - Lighter and better than Yagi

Postby Grzyadms4x4 » Tue May 19, 2009 3:33 am

That's not a bad price, who makes it?
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Re: Moxon Rectangle Antennas - Lighter and better than Yagi

Postby livetohunt » Tue May 19, 2009 4:11 am

I'm not sure who its made by I will look in the am and let you know.
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Re: Moxon Rectangle Antennas - Lighter and better than Yagi

Postby huntwithkids » Sat Jan 23, 2010 2:09 am

Hey I like the idea with the rectangular ant. I could not get the calculator on the link to work for me. It came up but I couldn't change the fields. Do you know what the dimensions would be for a 217/216 freq?
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Re: Moxon Rectangle Antennas - Lighter and better than Yagi

Postby Grzyadms4x4 » Mon Jan 25, 2010 5:51 pm

Here is a screen capture of a moxon for 216.5mhz. I did it in millimeters because it was easier to get your measurements right. Let me know if you need any more help.

Zach
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Re: Moxon Rectangle Antennas - Lighter and better than Yagi

Postby dubl_t » Sun Nov 21, 2010 5:11 pm

link to another Moxon calculator for those interested:
http://n3wwn.futuretek.cx/calcs/moxon.php4
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