[600MRG] NDB Antenna Calculator

[Edward R Cole]

I played with it and get quite a bit lower radiated power than my 
other calculations.  I do not know the coil Q so tried some values 
and see R change accordingly.  So I am guessing if I measure the coil 
resistance with a multimeter I could find the Q backwards by 
adjusting the value of Q till R reads what I have measured.

What I am getting is RP =1.97w.  I previously measured ground 
resistance with my modified MFJ analyzer as 20-ohms.  My previous 
calculations gave radiation resistance as 0.83.  This calculator 
gives is as 0.34 ohms for coil Q=100

I can only guess that the model is a single wire inverted-L.  My 
antenna has three parallel wires in the vertical section and two in 
the horizontal top section.  I would guess that would increase the 
top capacitance and lower the Q of the antenna.  I did my previous 
modeling with EZ-NEC demo v.5.0.

73, Ed - KL7UW

At 08:34 AM 9/27/2015, sbjohnston at aol.com wrote:

>
>One of the Australian 630 meter enthusiasts, VK5ABN, has created an 
>online antenna calculator based on published equations for 
>Non-Directional Beacon antennas.  These are similar to many of our 
>amateur antenna efforts.  See message copied below...
>
>Steve WD8DAS and WH2XHY
>
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>G'day,
>
>FYI: I've created a web page using equations found in "NDB Antennas" by
>John R. Pink. to calculate and evaluate antenna parametric. It can be
>found on
>
>http://ping.net.au/index.php?mode=antcalc
>
>Here you will also find a link to the original article. This is work in
>progress, so please let me know if you find any errors or have
>suggestions for improvements.
>
>I found it very useful in aiding me to improving the performance of my
>MF antenna.
>
>Enjoy,
>
>73, Berndt
>VK5ABN
>
>
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>
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73, Ed - KL7UW
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