Total posts : 45366
A NEC model of this circuit…
Important to note that I can’t take credit for, or defend, the tapped inductor concept.
The approach outlined in the two threads noted was an adaptation of some ARRL materials for the AM BCB by radio engineer Ernie Wilson of Pan Axis, taken from his practical guide to short AM antennas called ANTSAM, still available here:
ANTSAM AM/MW ANTENNAS ($7.50)
Iincludes general antenna theory, vertical half-sloper, multi-element, shunt-fed, and helical wound antennas, PLUS increasing efficiency by good ground conductance, radials, loading coils, and capacitive hats. Vertical antennas from 10 to 50 feet are covered. Includes excerpt of “Part 15” FCC Rules which limit antenna height of 100mW “broadcasters”.
Excellent reading, highly recommended.
While the ordering info states a $10.00 minimum is required, if you send a money order and a large SASE you can order for less.
Reminds me of Don Lancaster’s addage about “an hour in the library is better than a month in the lab” 🙂
Experimental broadcasting for a better tomorrow!