Another thing I noticed after reading the patent info that Bob posted the link to, that got me thinking...
About 2 years ago (last time I frequented this board), I left after having a heated discussion with someone about antennas, and the fact that these "idiots" making 5/8 antennas today where really making .64 wave antennas, etc. because NOBODY was taking electrical length into account. I was basically handed my hat by the "supposed" experts (who couldn't actually be BOTHERED to read anything by the ARRL, Orr, or anything else) that told me there was no such thing as "electrical length" of antennas.
Well, to hand you your asses back, on the proverbial platter, take a look at the radial terminology in the patent. Then take a friggin look at the REASON for the impedance loop on the Sigma IV style.
It broadbands the antenna, as well as shortens the ELECTRICAL LENGTH of the 'radials'.
There, smart-asses. Have it your way, even if it's wrong.
Antennas generally require a 4 to 6 percent shortening, depending on a number of factors, but that's the generally accepted rule for aluminum tubing, NOT covered. Heat shrink your antenna, and the dimensions all CHANGE!
Thought I'd throw that back into the game.... Seems some supposed, recognized "experts" have just been proven wrong.
--Toll_Free
