Date: Thu, 3 Mar 2016 19:25:25 -0400
From: Herbert Schoenbohm <herbert.schoenbohm@gmail.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] 160M Antennas
Since the tower itself is the other half of the antenna itself what you
have is just found another way to feed the tower which does a
significant portion of the actual radiation. Put in at least 16 radials
and it will work even better.
Herb Schoenbohm
## and the 1/4 wave sloper will work even better, when you have some yagis on
top of the tower !
Its an excellent ant for folks who don’t have room for radials, or who have
small city lots etc.
Its fine to say lay out a bunch of radials..... but on 160m, they will be way
too short. Then you will also
typ have the home + garage in the way. You cant lay radials on top of
pristine lawn, so they would have to
go slightly below ground. It’s a lot of effort for only a tiny improvement.
## What the 1/4 wave sloper really has going for it is....it gets the
feedpoint well above ground, like way up
there. Yagis on top of the tower is a capacity hat..which imo is a free lunch.
The 1/4 wave sloper is dead
simple,just one wire. Its very easy to broadband too, just add a couple of
relays and a small loop, or coil
at the feedpoint. It’s also easy to load the sloping wire, if you don’t have
room for the 130-140 ft of sloping wire.
You can easily go horizontal at the bottom end of the sloping wire, parallel to
the ground, You can also linear load it.
You can also install a small coil at the feedpoint to add XL to the wire. You
can also install a coil part way out from the
feedpoint. You are almost better to model it as an upside down GP.
## with the feedpoint way up high off the ground, it will radiate better. I
have tried full sized 1/4 wave ground mounted
verticals on 40m, made from 3 inch od al irrigation tubing...with a LOT of
ground mounted radials, like 80-90 of em,
and as long as 70 ft. Guess what, it all radiates into the side of the home
and garage. That particular home I had used AL siding
on both the home + garage. Even stucco sided homes will have miles of chicken
mesh beneath the stucco. You end up radiating into
your neighbours homes and garages too. Then tried the same vert, but on the
roof, with radials laid out on the roof, like 80 of em, varying
from 25-35 ft. Now that worked extremely well, way better than the ground
mounted version. Then up went the new tower. The tower
was 20 ft sections with the 1st 4 ft into concrete. So top of 1st section
was 16 ft above ground. Top of next section was 36 ft above grnd.
Presto, the swr on the roof top 40m vertical went to hell.... with the 36 ft
tower too close in proximity. Then added more tower sections
and ended up at 76 ft. Swr dropped back down on the roof top 40m vert... but
it never performed worth a damn after that.
## I have yet to see one of these ground mounted verticals in typ back yards,
work worth a damn...on the lower bands, regardless of
radials used. You cant install radials 360 degs..with a home etc in the way.
The 1/4 wave sloper is an excellent alternative..esp on 160 +80m.
Jim VE7RF
the tower was up to the 36 ft level, the t
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|