Howdy NGers,

I was curious about another "miracle" short vertical, being subject of great
interest, patent by Robert Vincent and Physics dept. of University of Rhode
Island. I got up at 4 am, drove to Boxboro ARRL convention and eager to see
what are we missing.

Not much!

Giveaway was opening statement something like: how to make shortened antenna
with more gain (compare to what? I guess light bulb :-)

In the "theoretical" portion of the presentation audience was told that current
across the helical coil decreases away from the feed point, while across
loading coil it stays constant. Due overcrowding of "inventor" I did not
persist in breaking through and asking for enlightenment.

Author claims more gain (familiar), better bandwidth (doesn't get it why) and
small size (of course). Showing measured graphs with current and phase
distribution along the radiator. Works very well! (Many stations worked.)

He showed how to measure current at the antenna using ferrite pickup
transformer way up the antenna and cables to the instrument (handsomely
detuning and distorting the measurements).

I suspect that "broad bandwidth", (SWR 2:1) was achieved thanks to losses in
the coils and dielectric, as "confirmed" by his statement that coils were fried
when power was applied.

What is it? Basically helically wound coil starting from the base, about half
way up the radiator, then piece of straight tubing, than loading coil, then
tubing and in some case top hat (works better :-). Matching to 50 ohms is done
by picking tap at the base, few coil turns up. That is 3D version.

He showed some "2D" versions, having "coils" made of basically coil formed as
hairpin loops instead of classic solenoid, also the loading coil. So kind of 2D
- 3D antenna :-)

I wanted to make a bet that my single loading coil loaded vertical would cream
the "miracle", but there were so many worshippers paying compliments to the
inventor, that I resigned not to stay for the second hour of lecture how to
build it.

I saw no trace of any modeling, just experiments using wrong tools.

So brace yourselves for another "miracle" in the arsenal of very small and more
efficient antennas. It should be a hit with CBers and other suckered users.

So that's it (oh, no chokes in the feedlines), I hope U of RI is proud of this
breakthrough, I can sleep well now. Back to DR1.

Yuri, K3BU
with more info that could have saved lotsa experimenting at
http://www.k3bu.us/loadingcoils.htm