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Re: [TowerTalk] Horizontal Dipoles

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Horizontal Dipoles
From: "Lux, Jim" <jim@luxfamily.com>
Date: Mon, 10 Jan 2022 16:40:48 -0800
List-post: <mailto:towertalk@contesting.com>
On 1/10/22 4:10 PM, Don wrote:
Question for the antenna gurus on this site.

I don't have any modeling SW nor experience with such SW. With that known, I have a question about a horizontal 1/2 wave dipole at a single height.

I understand the radiation pattern for a straight dipole, old school.

What I want to know is the pattern when a dipole has one leg 90 degrees from the other, again at a single height (not an inverted V).

Like a V, all in a horizontal plane?

You'll see this sometimes referred to as a skew dipole.

It has a dipole like pattern, oriented broadside to the "opening" of the V.

The phase center is about 1/3 of the way down the V.  The gain is slightly lower (A perfectly straight dipole is 2.1 dBi, an infinitely short dipole is 1.5 dBi, a V is somewhere in between)

The impedance is closer to 50 ohms (a spread of 120 degrees puts you right around 50 ohms as I recall)

They're pretty common on LPDAs for higher frequencies (TV receive antennas).


If you want omni, that's done with a turnstile (3 or 4 dipoles in a circle).  See, e.g., BigWheel antennas for VHF and UHF, or a Lindenblad (for CP omni)


Would it be similar to a quadrant antenna, and almost omnidirectional? A friend contends not, that the quadrant antenna is a full wave dipole, not a 1/2 wave and the pattern would be askew but not omni.

Answers?

Don W7WLL


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