On 2/18/2011 7:12 AM, GEORGE WALLNER wrote: > So if you can add > top loading, do it. Don't worry about it being > assymetrical: the high angle radiation will be a small > percentage of the overall energy radiated (better then > burning it in the ground, anyway).
I agree conmpletely. The details of the geometry of top loading can have a SMALL effect on the total picture. It's a lot like radials -- don't worry about ideal, just try to do MORE. :) My Tee vertical is 86 ft vertical and more than 100 ft horizontal over sloping earth. It makes the electrical length greater than a quarter wave, so that the feedpoint Z is 50 + j 250 (that is, inductive), and the current maxima is moved up the wire a bit. I then added capacitance in series (a few hundred pF) to tune out the inductance, yielding 50 ohms to match the coax. Another un-related trick, learned years ago from the ARRL Antenna Book -- I doubled up on the vertical wires, using two of them in parallel at top and bottom, but spaced apart roughly 4 inches. It increases the SWR bandwidth enough that I can work up to about 1920 kHz during a contest without needing an antenna tuner for my Titan 425 tube amp. My vertical uses #10 THHN stranded wire. 73, Jim K9YC _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK