It depends ENTIRELY on how they are foreshortening the antenna. If they are
using super-wide conductors (the entire width of the blade) to get the
foreshortening, then it is a very efficient antenna. If they are using loading
coils inside with a relatively narrow antenna diameter, it is a very inefficient
antenna.

The only way to know for sure is to ask the manufacturer for a data/spec sheet
or cut the antenna open.

Jim


(JFLEISC)
shared these priceless pearls of wisdom:

-Can anyone tell me if there are any significant electronic performance
-differences in those "shorter blade type" (just over a foot) VHF com antennas
-from the standard length stainless whip?
-
-Jim

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com