[Elecraft] Miniature self-supporting HF antennas

[Jim Brown]

On Mon,7/20/2015 1:56 PM, David Gilbert wrote:
> It all depends on the rest of the antenna, and yes, a very short 
> antenna with a crummy coil in the wrong place is going to suck.  But 
> some of the best antennas on the market right now use coil loading 
> very effectively.

There was an excellent piece in QEX a year or two ago devoted to the 
design of short loaded antennas. It was published in two parts -- one 
dealt with measurement, the other with studying the effect of the 
position of the loading coil.

The executive summary -- the part of the antenna carrying the greatest 
current does the most radiating, and for most short antennas, that's the 
part of the antenna closest to the feedpoint. The current distribution 
depends on the electrical length, including that coil. A loading coil 
near the feedpoint seriously degrades the radiation efficiency of the 
antenna, because the current maxima is in the coil, but the coil doesn't 
radiate! SO -- loading should be as far as possible from the feedpoint! 
All of this was borne out by the measurments.

73, Jim K9YC