To: | N4CW@aol.com |
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Subject: | Re: [TowerTalk] Modelling Dilemma |
From: | Terry Conboy <n6ry@arrl.net> |
Date: | Thu, 09 Sep 2004 19:26:05 -0700 |
List-post: | <mailto:towertalk@contesting.com> |
At 05:59 PM 2004-09-09, you wrote:
Using EZNEC 2.0, I model a one-wavelength wire at 50 feet above real ground Bert, In the first case (50% point), what you have created is often called "Two Half Waves in Phase". It has a high impedance feed and if you look at the currents, you'll see that they are indeed in phase, which is why you get a nice broadside pattern. In the second case (25% point), you have made a long wire antenna. In a long wire, currents alternate in phase by 180 degrees every half wavelength. In your case, you have two half-waves out of phase, which produces a null normal to the wire. The feed impedance is relatively low (100 ohms or so) since you are feeding at a current loop. If you make the wire 2 wavelength long, and feed at 12.5% from one end, you will see that the main lobes get closer to the ends of the wire and you pick up 2 side lobes, too. When I first got EZNEC, I stayed up all night playing with Roy's darn program! 73 Terry N6RY _______________________________________________ See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA. _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk |
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