[600MRG] A TI-84 program for Radiation Resistance of a vertical on 630m

[Neil Klagge]

 LF/MF gang,

I wrote a program for my TI-84 graphing calculator to find the radiation resistance, Rr, of a short vertical for 630 meters with (or without) a top load wire. It works for any configuration of top loading whether it is an inverted L, T or several top wires as long as the top wires are horizontal to the ground and the total of the vertical plus top load wires do not exceed about 30 degrees of the wavelength. It can also be used to estimate the Rr if the top load wires are sloped downward at about a 45 degree angle (see below).



The screen shots of my TI-84 show the programming lines of the Radiation Resistance calculator. The main formula I used was equation "[5a]" from ON7YD's website on this page:   http://www.strobbe.eu/on7yd/136ant/#Monopole

Rik's equation used meters which I converted to feet in my TI-84 program. I also reduced some of the math so that this program works for 630 meters for simplicity sake. Do not use it for 2200 meters or any other band. (for use on 136 kHz, see 'NOTE' below)



To find the Rr of a vertical with sloping top load wires, first find the Rr assuming the top wires were horizontal to the ground. Next, find the Rr of the vertical without any top loading. The Rr of the antenna with the sloping wires is close to the average of those two answers.



Here are the programming steps. They should also work on previous models of the TI-80 series of graphing calculators.

PROGRAM: RRADVH1    (or any name you want to call it)
:Disp “ENTER FEET”
:Input “V? ”,V                  (total height of the vertical portion)
:V/3.28->V                       (makes the equation work for ‘feet’)
:Input “H? ”,H                 (total length of all top loading wires, or 'zero' if no top loading)
:H/3.28->H
:((10H+6V)/(5H+6V))^2*V^2/1010->R    (the 1010 makes it work at 475 kHz only)
:Disp “RRAD IS ”
:Disp R
:Disp “OHMS”
:

 (NOTE: for 136 kHz change the 1010 factor to 12300 for a close approximation of Rr)


73

Neil, w0yse, CN85rq
Vancouver, WA

My ham radio website: http://w0yse.webs.com/
<http://wg2xsv.webs.com>
My Faith website: http://neilsfaith.webs.com/
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