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

On Mon, 29 Aug 2005 15:17:01 GMT, 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.


Your subject line raises thoughts of many people separated by a common
language.

The usual reason for using four radials of certain length is that they
are elevated and resonant. Multiple radials of different length are
often operated in parallel because it is thought that there is then a
set that is optimum for each band.

Anyone who has tried to operate multiple dipoles in parallel will know
that without heroic effort this is a false premise, nevertheless, the
practice continues.

When you bury them, the radials are no longer resonant (at least where
you think they are) and trying to use multiple sets is an even less
good idea. You should use lay as many radials as possible. A rule of
thumb would be to make them at least as long as the radiator is high.

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

"Paul Hinman" wrote in message news:NFFQe.330061$5V4.212744@pd7tw3no...
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.
-------------------------------------------------------------------------------------------------
Why would you want to spend the money and rent a trencher? Use it for a toy. If you have a lawn edger (if not borrow one) use that and cut a 2 to 4 inch gruve/s in your yard and lay your radial/s in them. In about a week they will fill in by themselves and you will never notice them. You don't need to bury them as deep as a trencher would dig.
------------------------------------------------------------------------------------------------------------------
Thanx for any responses.

Paul VE6LDS

"Paul Hinman" wrote in message
news:NFFQe.330061$5V4.212744@pd7tw3no...
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.

=================================
Paul,

When buried, even only shallow buried, radials become almost
non-resonant and their exact lengths, depth and thickness don't matter
very much.

What matters is the number of radials. The more radials there are the
better. However there is a law of diminishing returns and after 10 or
20 have been laid, depending on soil resistivity, not much happens.

But to bury a number of radials close to each other in a common trench
constitutes only ONE thick radial. With 4 trenches you have only 4
radials. They behave better when wires are uniformly, radially
distributed.

No need to buy a digging machine. Just lay some uniformly distributed,
shallow-buried wires, not necessarily all of the same length.

First try about 8 wires. If after trying out the system you feel
dissatisfied you can easily lay some more.
----
Reg, G4FGQ

Anyone who has tried to operate multiple dipoles in parallel will know
that without heroic effort this is a false premise, nevertheless, the
practice continues.

Huh? Never had a problem here. But I don't "stack" mine like
some people do. That's what causes the coupling problems.
If you parallel feed two dipoles at right angles, there is very little
interaction at all. I spread mine apart as far as possible.
Problems are rare, and easily cured by just moving a wire
a few feet if it happens. It's the ones who tightly stack them with
short spreaders, that have the nightmare tuning problems.

Multiple radials of different length are
often operated in parallel because it is thought that there is then a
set that is optimum for each band.

Well, there is a set that is tuned for a certain band. They won't work
worth a hoot if they aren't resonant. But this applies only to
elevated
radials. On the ground, I agree...measuring is a waste of time.
Doesn't matter if the wire is insulated or not. Will act much the same
either way.
MK

Your making it tough on yourself. Lay the wires out on the grass. Get a bunch of coathangers that have multiplied in your closet and cut 6" pieces and bend into a "U" shape and use them to nail the wire to the ground.

Your lawnmower will never touch them and you save the rental cost of a trencher and clear out the coathangers. A real win win situation.
"Paul Hinman" wrote in message news:NFFQe.330061$5V4.212744@pd7tw3no...
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

This has been my favorite way for a long time. The wires remain
removable and pretty much become hidden in the turf after a year. A
lot depends on the nature of the soil you are dealing with. North
Carolina red clay in August is especially tough. Six inches is longer
than I have needed. In the past I have ignored what might be optimum
and instead installed the radials I could. I am inclined to use
electric fence wire because it is cheap. Just use more of it. I
realize that this approach is not very academic, but I feel it yields
the best results in the long run for a given set of conditions.

My current location seems especially prone to lightning so I expect it
will be prudent to tie the radial system to the house ground with #6
copper wire.

On Mon, 29 Aug 2005 22:53:17 -0400, "Fred W4JLE"
wrote:

Your making it tough on yourself. Lay the wires out on the grass. Get a bunch of coathangers that have multiplied in your closet and cut 6" pieces and bend into a "U" shape and use them to nail the wire to the ground.

Your lawnmower will never touch them and you save the rental cost of a trencher and clear out the coathangers. A real win win situation.
"Paul Hinman" wrote in message news:NFFQe.330061$5V4.212744@pd7tw3no...
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

On Mon, 29 Aug 2005 15:17:01 GMT, 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

A trencher is far overkill. Any sufficiently hard disk can cut through
the turf and inch or so. That is all that is needed for burying a
radial. I have about 30 radials for a Butternut Ground plane. I used
an old circular saw blade which I put on an improvised axle to cut
through the turf. I used whatever wire I had on hand at the time, some
bare, some insulated. It works fine. One thing to notice though is
that more radials will somewhat increase the bandwidth of the antenna,
but not anything which can't be overcome with a transmatch. The
radials do have to be radial from the antenna. If you crave super
efficiency though you may have to go to the extremes of Jerry Sevcik
(sp) who wrote a series of articles and books on vertical antennas in
the 70's. I have nearly 200 countries though with just the Butternut
and about 100 watts so you will get out.

Jon W3JT

That should have been more radials DECREASE the bandwidth.
Sorry,

Jon W3JT

On Tue, 30 Aug 2005 09:29:49 -0400, J. Teske
wrote:

On Mon, 29 Aug 2005 15:17:01 GMT, 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

A trencher is far overkill. Any sufficiently hard disk can cut through
the turf and inch or so. That is all that is needed for burying a
radial. I have about 30 radials for a Butternut Ground plane. I used
an old circular saw blade which I put on an improvised axle to cut
through the turf. I used whatever wire I had on hand at the time, some
bare, some insulated. It works fine. One thing to notice though is
that more radials will somewhat increase the bandwidth of the antenna,
but not anything which can't be overcome with a transmatch. The
radials do have to be radial from the antenna. If you crave super
efficiency though you may have to go to the extremes of Jerry Sevcik
(sp) who wrote a series of articles and books on vertical antennas in
the 70's. I have nearly 200 countries though with just the Butternut
and about 100 watts so you will get out.

Jon W3JT