Well Paul

Paul Hinman wrote:

I came across an interesting antenna the other day on the web. It
called for four radials for each band that one would want to use it
on. In order to protect the lawn mower I would like to bury the
radials. If I use insulated wires for the radials can I bury multiple
radials for different frequencies in the same trench. I would rent a
small trencher like they use for underground power and utility feeds,
make four trenches and drop in the radials, then cover them.

Thanx for any responses.

Paul VE6LDS


Based on practical experience with elevated 4 square vertical arrays on
40 meters, I suspect that might be a 'grave' misteak! Chortle..


I've noticed that with the elevated 4 square arrays, actual connections
between elements very much change the elements in the way they present
to the feed lines. I'm talking about completely grounded vertical
elements and feeding each element with gamma match techniques. Note
that in the common 4 square vertical low band array configuration, the
spacing between the towers is roughly a quarter wave apart. That
defined, it's obvious that you can proceed away from any given vertical
toward another in the aray and .. you either reach or can reach it with
the tip of a radial from another element. Thus you have the possibility
of actually connecting the elevated radial to an opposite element's
actual tower. Remember, the towers are all grounded. Your feed
operation as to the gamma match section is already bonded to the
vertical tower at that elevation point for the elevated radials.


Not surprisingly, I've found that connection of these between tower
spaces with a common wire between the towers on the elevated 4 square
model DOES change the parameters required for gamma match dimensions and
tuning a lot more than you might expect. Further, if you position the
radials so that they extend so they don't 'aim' toward the opposite
poles and toward the center, that also changes the practical match
operations of the gamma match sections markedly as well.


Further, even if you cross connect the between towers chort-line
distance. obiously extending the radials directly opposite away from the
poles, and then move toward the center where the relay switch box is
located, you'll find another interesting fact about this there.


Simply connecting those cross-array wires together at the relay box site
also has major implications on the tuning of the gamma match sections
for the towers. Recall that the 'connection' to the towers, in this
case, also is the shield of the coax cable matching section which
connects each element of the 4 square to the relay box at the middle of
the array. If I just open up the ends of each radial from each element
there where it reaches that center pole holding the relay box, I get
very noticable changes on the whole array and matching differences.


I can see and verify it with my MFJ antenna analyzer. I don't have the
drive and desire to spend the time doing the exact match distortion
paper work to define this for publication or whatever. Part of the
reason to use the gamma match technique was to minimize setup time for
these arrays, at the same time I solidly ground each tower for lightning
protection. That last is particularly important for elevated radial
vertical arrays in my very person experience at my W5WQN low band site.


Based on the above, and the understanding that any given wire laying
next to another wire, in any location free space or whatever, is
mutually affected by the other wire, I'd think what you propose is
likely to lead to a ..

grave error!

Mike Luther - W5WQN

--


-- Sleep well; OS2's still awake!

Mike Luther