# LF ERP w/ 1500W & 200W

**Paul L. Rinaldo**
prinaldo@mindspring.com

*Tue, 10 Feb 1998 07:28:27 -0500*

Dear Andre,
You probably knew this all along.
73, Paul, W4RI
>*BARGHAUSEN EQUATION
*>*
*>*The Barghausen Equation expresses the dB gain to be expected from a short
*>*(less than 1/4 wave) vertical antenna. I have located the equation but
*>*not the Barghausen reference paper. As I recall, the equation resulted
*>*from curve fitting a few data points obtained from measurements of the
*>*radiation from a jeep radio operating over lossy ground with various size
*>*whips on HF frequencies below about 6 MHz. There are probably better
*>*algorithms for this application! This is submitted as a rough
*>*approximation of TPO verses ERP. The equation is:
*>*
*>*dB= -6416.702R^4 +6091.33R^3 -2179.89R^2 +364.817R -25.646
*>*
*>*where:
*>* R = (Length of radiator) / (Length of one wavelength)
*>* R^x denotes raising R to the power of x.
*>*
*>*Solutions of the Barghausen equation at 180 kHz with various antenna
*>*lengths (feet) and transmitter power outputs of 1500 and 200 Watts
*>*predicts the listed ERP in Watts.
*>* TPO TPO
*>*Antenna Wave- dB Ant 1500 W 200 W
*>*length length gain ERP-W ERP-W
*>*50 .01 -22 9 1
*>*100 .02 -20 19 2
*>*200 .04 -15 50 7
*>*400 .07 -11 230 30
*>*600 .10 -5 520 70
*>*800 .15 -3 810 110
*>*1000 .19 -2 1000 140
*>*
*>*73, Dick Wilder, K3DI
*