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Author Topic: Extending HT Range With a Cubical Quad for UHF 70cm 432mHz.  (Read 2658 times)

gil

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Extending HT Range With a Cubical Quad for UHF 70cm 432mHz.
« on: November 24, 2016, 11:47:40 AM »
Hello,

Having some difficulties reaching my regional UHF relay in Lille, I decided to build a cubical quad antenna. Why not a Yagi-Uda? Because the quad has an impedence of 50 Ohms! No need to build a matching system. So I went looking for a cubical quad calculator:

http://www.csgnetwork.com/antennae5q2calc.html

Here are the results:



I thought of an original way to build it, unlike anything I have seen before... You'll just have to wait to see the design, but here is a picture to get your imagination going  ;)



Gil.

gil

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Re: Extending HT Range With a Cubical Quad for UHF 70cm 432mHz.
« Reply #1 on: November 24, 2016, 04:01:03 PM »
This photo should make things easier to picture...



Gil.

rah

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Re: Extending HT Range With a Cubical Quad for UHF 70cm 432mHz.
« Reply #2 on: November 24, 2016, 04:23:35 PM »
Eagerly waiting for your next pics. :)
Yaesu FT-897
LDG AT-200Pro II
Icom IC-91A

gil

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Re: Extending HT Range With a Cubical Quad for UHF 70cm 432mHz.
« Reply #3 on: November 24, 2016, 08:27:20 PM »
Here is the last one for tonight. Only the reflector is glued in place. The three other elements are only there for the photo. I do not know if reflector and directors placement affect SWR so I did not want to commit to the calculator's results right away. Anyone knows? I have a VHF/UHF SWR meter on order... Still missing three aluminum rods since this is a seven-element quad! I also have an N-type female connector ready, along with an N-to-SMA_male cable.

The aluminum rods will be soldered end-to-end using a drop of vaseline as flux. I read about this trick on a French amateur radio site. I was going to say "a French Ham site," but it sounded too much like some dish ::) The driven element is copper. I left a one-centimeter gap on one side for feeding.

The vertical sticks you see in the middle ensure correct element placement since the squares are of decreasing size. I hope the whole shebang doesn't require millimeter-precision. I am close, but it won't be perfect. There are too many variables to get everything perfect by hand.

I think after setting everything up properly I might close the box. It would make it much stronger and look like, well, a box... It won't be an antenna to use on top of a mast, but a portable one.



Gil.
« Last Edit: November 24, 2016, 08:35:02 PM by gil »

cockpitbob

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Re: Extending HT Range With a Cubical Quad for UHF 70cm 432mHz.
« Reply #4 on: November 26, 2016, 12:31:35 PM »
Fascinating.  Love your woodwork!  7 elements should get you out there. 

My Arrow hand held satellite Yagi is a nice 50 Ohms, but it does have that gamma match that has a lot of drawbacks.  Mainly it's hard to make it water tight and weather proof.

Can't wait to see your final product!

gil

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Re: Extending HT Range With a Cubical Quad for UHF 70cm 432mHz.
« Reply #5 on: November 27, 2016, 07:14:13 PM »
Thanks. I need to wait for the SWR meter I ordered to go any further...

Gil

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Re: Extending HT Range With a Cubical Quad for UHF 70cm 432mHz.
« Reply #5 on: November 27, 2016, 07:14:13 PM »