[Antennas] How well do multi-band verticals operate?

2002年8月18日 14:31:06 -1000

One way to learn for yourself is to simply tune in to any one of
the NCDXF worldwide network of high-frequency radio beacons 
on 14.100, 18.110, 21.150, 24.930, or 28.200 megaHertz.
If one of those bands is open, you will certainly hear at least
the 100 watt call sign and first of a series of "dahs". Following the
100 watt signal is one at 10 watts; another at 1 watt, and a final
output at 100 mW! You might be surprised from what far away
place you will hear the 1 or 0.1 watt signals. Yes it takes some
time to monitor each of the five bands from each station about
the globe -- but what an education in "real time" propagation
conditions!
It is also helpful to have some sort of program to tell you which
station about the world is transmitting on a given band at a
particular moment. The one I use is from Jim Tabor; called
"Active Beacon Wizard". See:
http://www.taborsoft.com/abw/
(I just use the program, no connection with Kangaroo
Tabor Software.)
These beacon signals are transmitted from a 5-band vertical antenna.
I have searched and searched the NCDXF web site, and the
referenced QST articles, but have not found the kind/mfgr/etc.
about these verticals. But multiband verticals they are.
You can learn just about all else about the network of beacon
stations spanning the globe at:
http://www.ncdxf.org/beacon.htm .
I also have the suspicion that there are NO radials under these
beacon vertical antennas. Maybe someone out there can
actually tell us what kind of verticals these are, and whether
or not they have radials, elevated, on the ground or none, hi.
73, Jim KH7M