[Antennas] More Questions on Multiband Antennas

[David J Windisch]

Hi, all concerned:

Reverse-engineer (you know, divide 468 by length-in-feet) the 102-foot
length-number, and you'll find out that it's a half-wave on about 4.67 MHz,
which further reverse-engineers to 3 half-waves on 14 MHz.  Yet another
time, reverse-engineer the length with the demo version of EZNEC to see the
patterns (and feed-Z's), think about the data you've gathered, and you may
get some insight as to why G5RV chose the 102-foot length long ago.

Fwiw, I use a couple of 3/2-wave dipoles (with "balanced tuners" and owls,
and I'm not going there today) in lieu of alternative antennas, cuz they're
not critical in any important respect, and from the midwestern US, they have
six good lobes in desirable directions, and I can "phase" them to get some
useful signal increases in certain directions, and I can make the included
angle 120 degrees for further pattern-enhancement, and I have enough land
and suitably-placed trees to support them, and I'm not interested in pushing
the performance envelope: If it came down last winter, it was too big.

The "468" magic number is found in ARRL and many other pubs.  Well,
publications ;o)

73, Dave, N3HE

----- Original Message ----- 
From: "Kevin Nathan" <k7rx at comcast.net>
To: <antennas at mailman.qth.net>
Sent: Wednesday, September 15, 2004 1:08 AM
Subject: [Antennas] More Questions on Multiband Antennas


> Hello All,
>
> When I asked my question concerning recommendations for multiband antennas
> which I might use to replace my current inverted vee which is 60 feet per
> side and fed with window line, the only recommendations I got back were
for
> full wave loops.  While this is ultimately my dream, I don't have the real
> estate presently to put up one of these.  So, I am back to trapped or
other
> types of antennas.  To be honest, I'm not finding much in terms of dipole
> antennas trapped for the WARC bands as well.
>
> In conducting research on the net, I keep seeing the figure of 102 feet
pop
> up again and again.  This, of course, is the length of the classic G5RV
and
> I have found at least two other references to multiband dipoles for 80 and
> up with a length of 102 feet.  Is there something magical about this
length?
> This may sound silly, but is there a magical suggested length for the non
> resonant dipole for 80 and up?  Is 102 feet this special length?
SNIP