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I'm thinking about phased antenna arrays, and am wondering if it's possible to have three fixed position antennas, and vary the length of their individual feedlines to the common point through mechanical means.

The best way to describe what I'm thinking is making a section of coax out of two telescoping sets of tubes, one outside shielding, and one inside conducting. I'd probably shoot for something other than telescoping antennas, and I'd be using a cheap DC drill with either woven thread or an acme screw to move the inner parts relative to the outer parts.

I can leave one antenna connected to the common point via fixed length coax, and then connect the other two with these variable length coax devices in the feedline.

It seems like it's overly complicated, and that someone probably has come up with something better for switching a phased antenna array to point in any direction. Surely someone has already built one (or perhaps it exists commercially and I just haven't seen it yet) or people have considered it, but other solutions are better.

What are other options I should consider?

Adam Davis
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  • I don't have any knowledge of the field, but in case you don't know already, "electronically steerable" phased arrays are what you're asking about except with non-mechanical means for delay/phase shifting. – Kevin Reid AG6YO Dec 07 '13 at 19:13

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I don't know about mechanically steerable arrays, but there are several hams locally here that swear by a four-square electronically steerable arrays. The setup is typically done for 40m and is an array of four 1/4λ verticals arranged in a square 1/4λ apart. You run one feedline to a remote switch located in the center of the square and 4 identical length feedlines go from there to the individual antennas. You orient the square so the sides point in the directions you want to favor. A controller goes in the shack to steer the array.

One company here in the US that makes an excellent controller is DXEngineering. The controller runs about 200USD, one plus the remote switch is about 600USD. The manual is available online so you can read up on it and see if it's something you're interested in. I don't have a stake in them, but I have personally found their customer service and shipping speed to be excellent. If I had the room at this QTH I would definitely put up one of these. Alas, it will have to wait a few years...

WPrecht
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