On Wed, 27 Sep 2006 09:50:17 -0500, K4SAV wrote:
>A 45 ft vertical for 160 is a little problematic.
Yes, but it can be made to work with a lot of top loading in the
form of a capacity hat, and an effective counterpoise or radials.
Will it be as good as a quarter wave? Of course not. But it will
work. In general, the shorter the antenna, the more important the
radials. The more top loading the better, but it will load fine if
you have enough loading to get it within range of your antenna
tuner.
Very effective top loading can be obtained as simply as suspending
a vertical wire from a horizontal wire hung between two trees or a
tree and a house or a house and a tower, connecting the vertical
wire to the horizontal wire. Or it can be an inverted L. The
vertical wire will do most of the radiating, the transmitter sees
the length of vertical wire plus the length/capacitance of the
horizontal wire.
There are good discussions of antennas like this in Kraus (W8JK),
and ON4UN's book (Low Band DXing), which is an excellent resource
for 160/80/40 antennas. The vertical I described in an earlier
post in this thread works as the "T" form -- I tie both sides of
the feedline together and load it against 25 radials (and will add
more). In Chicago, I had a few short radials and a big wrought
iron fence. I wasn't the strongest signal on the band, but over
about two years, I had a lot of fun in contests and worked the
lower 48 and 20 countries.
73,
Jim Brown K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|