On 12/28/15 6:13 AM, john@kk9a.com wrote:
The 4 square spacing is much different for 160m, 80m and 40m. I do not see
how you could use the same verticals on each band.
If you want the classical 1/4 wavelength spacing between elements, yes,
you couldn't use the same elements for all three bands.
However, consider that one of the big assets of the 4 square is that it
allows significant F/B ratio or placing a system null on "the wrong
direction". You can do this with almost any arrangement of elements,
although the feed network isn't quite as simple.
Building a triband
vertical controller would also be a challenge.
Basically, you'd have 3 separate controllers, one for each band, with
appropriate tuned networks to get the phasing right for each band.
Actually, you could probably come up with a fairly simple relay system
to switch things around. And, the phasing network can be designed to
take care of matching the antenna, too.
A lot depends on the symmetry of your antenna array, especially the soil
properties. I've done some measurements on pairs of verticals at
various spacings in a local park, and there are significant variations
in soil characteristics over relatively small distances. Soil water
content is, I think, the big thing, but skin depth is a few meters, so
subsurface layers also have an effect.
Unless you're building your array in a uniform field with uniform
soil properties, like N6RK out in California's central valley (10,000
feet of perfectly uniform sediment washed out of the Sierra Nevada over
millenia, and remarkably flat for miles), your array won't perform like
the ideal array. It will probably be "good enough", but you might not
get a nice 20 dB null in some directions.
You can have separate 4
square arrays in the same area. I would pick a shortened yagi over a 4
square on 40m. Shortened verticals work fine on top band, even K9DX's
massive 9 circle array used Titanex (~90') verticals. It is easy to
homebrew a vertical of any height.
Finding an RF quiet location is very difficult. Even if you find a quiet
location, noise sources will pop up. Your odds are better the further you
are from civilization, but then you're also living far from services. Like
everything, there are compromises.
John KK9A
To: towertalk@contesting.com
Subject: [TowerTalk] 4 Square in the future?
From: "Gary Smith" <Gary@ka1j.com>
Reply-to: Gary@ka1j.com
Date: Sun, 27 Dec 2015 16:00:20 -0500
Hi,
I'm looking to relocate out of Connecticut & need to find a location
that is as RFI quiet as is realistic. I currently use a HI-Z
Triangular for my Rx and love the advantage of steering in Rx. I
would like to have not only the benefit of Rx but Tx with steering as
well. I'm not moving in the immediate future but I need to know some
thing before I start looking for the new digs and what I'll need to
accomplish my antenna farm goal is one of them.
What size Tx towers are a good compromise on 160 & I'd like to use it
on 80 & 40 as well, I can't see how I could afford to put up full
size 160 towers. I'm 65 and just can't put up towers by myself like I
have in the past. Well, maybe I could but it wouldn't be as fun as it
used to be.
Also, what controller should I look into for this? I need to factor
in the land needed and the expense of having the towers and equipment
installed. I've never looked into this before and am just starting my
search.
Any thought or links to topics that might help will be appreciated.
73 & Happy New Year!
Gary
KA1J
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