Topband: Radials Again

[Jim Brown]

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