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Old 23-Nov-2011, 6:48 PM   #14
GroundUrMast
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Join Date: Oct 2010
Location: Greater Seattle Area
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Some of the older information I've come across includes descriptions of a dual stack in which the upper and lower sections are tied together with a piece of open wire or twin lead and the transmission line is connected to the lower rhombic section feed point. This results in imbalanced current and voltage in the upper and lower sections and also drives the upper section out of phase with the lower section at any frequency other than one resulting in the phasing tie being 1/2 wave in electrical length (Or an odd multiple of a half wave. But three or five times the design frequency puts you in microwave ranges.) The vertical beam then skews up or down as the frequency moves away from design center.

So, I simply used a balanced feed arrangement which is not my invention. As you say, the technique has been used in most panel antenna designs. Notice in the quad stack, the top and bottom phasing lines are twisted 180 (a phase reversal at the design frequency), the center phasing link has no phase reversal.

Over real ground, I'd expect to see the pattern launch upward at anywhere from 2 to 12 degrees... depending on the antenna height and ground characteristics.

I have no plan to rotate this with a CM-9521a
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Last edited by GroundUrMast; 23-Nov-2011 at 7:22 PM.
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