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Re: 2 meter antenna is a 10 turn helix...



Hello JAVIER,

>This is an antenna of VK5ZAI, but I have never see one of this. 

Helix antennas are quite common in satellite work. As with all antenna
designs they have advantages and disadvantages. The axial-mode helix antenna
was developed by John D Kraus W8JK in 1946. All the variations are
thoroughly described in his book "Antennas".

I have used long helix antennas at frequencies of 435 MHz and above but they
are large and difficult to construct at 145 MHz. Tony's (vk5zai) antennas
are very well built and work very well. I have a jpeg photo of his latest
helical which I could send you if you wish.

The main disadvantage is that they are specifically wound right or left hand
in circularity and cannot be switched. You would need two of them if you
wanted to have both both right and left hand circularity.

Hope this helps JAVIER. Let me know if you need any more specific
information. I can send the jpeg direct to your email address if you would
like to see it.

Regards, Bill...vk3jt

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