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Re: [TowerTalk] Change in Frequency with Height above Ground

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Subject: Re: [TowerTalk] Change in Frequency with Height above Ground
From: Dan Maguire via TowerTalk <towertalk@contesting.com>
Reply-to: Dan Maguire <djm2150@yahoo.com>
Date: Fri, 27 May 2016 14:24:15 +0000 (UTC)
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Don W7WLL wrote:
>>> Lowering the height of an antenna above ground, such as a beam, will cause 
>>> the resonant freq to decrease, increase?

The "Resonate" button of the AutoEZ program makes short work of questions like 
this.  For example, create a 20m dipole model with an arbitrary length of 33.5 
ft at height "H" above ground.  Set up a series of test cases with "H" ranging 
from 5 to 100 ft, all at 14.2 MHz.  Select all the "Freq (MHz)" cells and click 
the "Resonate" button.  Like so:

http://s33.postimg.org/u5kmyan7j/resonate1.png

Then tab to the Custom chart sheet and plot Frequency on the Y axis vs Variable 
H on the X axis.  Here are the results for three different EZNEC ground 
characteristics.

http://s33.postimg.org/69rm0qscf/resonate2.png

For more examples of using the "Resonate" button see Step 6 here:

http://ac6la.com/autoez.html

Or see the fifth and sixth bullets here:

http://ac6la.com/aecollection2.html

Dan, AC6LA
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