On Mon, 2 Oct 2006 10:41:52 -0500, Mike(W5UC) & Kathy(K5MWH) wrote:
>So the question becomes; when do I reach the
>point at which I am wasting time, wire, money, and wear & tear on my tired,
>fat, old body? I have purchased another 2000 feet of wire should I need it.
Because this question is a very good one, it is one that has been asked (and
answered) over and over again. The best answer I've seen is in the latest
ARRL Antenna Book chapter on Grounding, by Rudy Severns, N6LF. A quick
summary has several parts:
1) Up to a point, more and longer is better
2) For a given quantity of wire, more short radials are better than fewer
long ones
3) For any given number or length, you reach a point where more is still
better, but not enough better to justify the cost/labor
4) The shorter the antenna, the more important more and longer radials are
5) The gauge of the radials is not important as long as they are
mechanically solid (that is, they last). #16, #14 are good. I'm using
insulated wire, both because I have good sources of it, and to minimize
chemical deterioration.
6) The uniformity of distribution around a circle is far less important than
quantity
7) It is NOT important that they all be the same length
8) Rudy's piece in the Antenna Book includes a table that shows, in summary,
the point of diminishing returns for a given quantity of wire, number of
radials, and length assuming they're all the same.
I've been studying this issue because I just moved to a new QTH and have
room for a decent vertical (and even an array of verticals) and radials to
go with it. My initial installation is 24 radials that are 1/8 wave on 160.
In Rudy's table, that gets me to within 2 dB of "ideal" on 160, and will, of
course, be better on 80. As I have time, energy, and junk wire, I'll add
more and make the existing ones longer. My radials are NOT uniformly
distributed -- nearly all are within about a 200 degree arc -- and some are
shorter. The antenna works well on 160 and VERY well on 80. As I expand the
radial system, I'll try to fill in some gaps in the arc, even with shorter
ones, but that will have to coincide with re-seeding a "sort-of" lawn. And
when I'm done, I don't expect to pick up much more than another dB or so on
either band.
Hope this helps. And DO buy the ARRL Antenna Book and study it. It is well
worth the time and effort. ON4UN's book is also quite good. Also, google the
archives of this list and the Tower Talk list. W8JI just wrote a nice post
on the topic a few days ago. I don't recall which list.
73,
Jim Brown K9YC
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