My homebrew 3 foot dia Magloop works very well vertically mounted 3 foot off
the ground but i`m wondering if maybe it could do a little better in the low
angle radiation department ....i seem to hear stations within 1000miles
consistently strongest.....VKs and stateside etc much lower !!!.....

The loop is mounted on a rotator above a groundmat buried about 6 inches
beneath the lawn and consists of 30 radials each about 30 foot long and the
loop is mounted in the centre, is that ok, or should i work the loop higher
than 3 feet above the mat, or remove the ground mat and work just with
medium loam soil underneath instead??........

Thanks to Cecil and others for help and advice in building the loop, it
tunes 40 thro` 15 meters......

Lee......G6ZSG.....

Lee wrote:
My homebrew 3 foot dia Magloop works very well vertically mounted 3 foot off
the ground but i`m wondering if maybe it could do a little better in the low
angle radiation department ....i seem to hear stations within 1000miles
consistently strongest.....VKs and stateside etc much lower !!!.....

The loop is mounted on a rotator above a groundmat buried about 6 inches
beneath the lawn and consists of 30 radials each about 30 foot long and the
loop is mounted in the centre, is that ok, or should i work the loop higher
than 3 feet above the mat, or remove the ground mat and work just with
medium loam soil underneath instead??........

With a low height "vertically polarized" loop the ground would never
hurt the antenna and always help it to some extent. The only exception
might be if the soil is so very poor it looks nearly invisible, or so
good it looks perfect.

I would not remove the ground mat, although 6 inches is pretty deep!

A small loop is a very inefficient radiator unless you do everything
perfectly, and if perfectly done it has mediocre efficiency.

So how did you build the loop?

Lee,
Signals within 1000 miles come through strongest because they are
nearer to you.

Also, with an antenna height of only 3 feet, low-angle reception and
radiation suffers from being screened by buildings and other
obstructions in the vicinity of the antenna.

At low heights there is a considerable power loss induced in the soil
under the antenna. Your radial system is of little use. Only a large
metal sheet placed on the soil surface would be effective.

Your buried radial system is an overkill. If it was removed you would
probably notice no difference in performance. But the radials will
perform an excellent service if you should later wish to erect a
vertical antenna above them.

An increase in height will result in better low-angle DX. Increasing
height to only to 8 or 10 feet should produce a noticeable
improvement. And loss in the ground will be negligible.

To get it above ALL low-angle obstructions, fix it to your house
chimney. ;o)
----
Reg, G4FGQ.

"Reg Edwards" wrote in message
...
Lee,
Signals within 1000 miles come through strongest because they are
nearer to you.

Agreed....

Also, with an antenna height of only 3 feet, low-angle reception and
radiation suffers from being screened by buildings and other
obstructions in the vicinity of the antenna.

Also agreed....

At low heights there is a considerable power loss induced in the soil
under the antenna. Your radial system is of little use. Only a large
metal sheet placed on the soil surface would be effective.

Yes...

Your buried radial system is an overkill. If it was removed you would
probably notice no difference in performance. But the radials will
perform an excellent service if you should later wish to erect a
vertical antenna above them.

That was what the groundmat was for originally, but my neighbours didn`t
like it, so, down it came....hence the magloop...

An increase in height will result in better low-angle DX. Increasing
height to only to 8 or 10 feet should produce a noticeable
improvement. And loss in the ground will be negligible.

I`ll try that Reg, i just wasn`t sure above which height would be of little
or no advantage, vertical....
but if the loop were horizontal then halfwave at the lowest frequncy i
suppose!!

To get it above ALL low-angle obstructions, fix it to your house
chimney. ;o)

No chimney Reg :-/

Thanks.....

Lee.....G6ZSG......

Reg, G4FGQ.

wrote in message
oups.com...

Lee wrote:


With a low height "vertically polarized" loop the ground would never
hurt the antenna and always help it to some extent. The only exception
might be if the soil is so very poor it looks nearly invisible, or so
good it looks perfect.

Loam!!!....

I would not remove the ground mat, although 6 inches is pretty deep!

????.......mat was the wrong word i suppose....ground system if you
wish......

A small loop is a very inefficient radiator unless you do everything
perfectly, and if perfectly done it has mediocre efficiency.

Better than the small low antennas that i could fit into a 35` x 16`
garden... ;-)

So how did you build the loop?

Oh, the regular circular shape 10`x 0.625" tube with a `T` shaped frame
support and motor driven cap........

Lee......G6ZSG......

I`ll try that Reg, i just wasn`t sure above which height would be of
little
or no advantage, vertical....
but if the loop were horizontal then halfwave at the lowest frequncy i
suppose!!

i used radials with my monopoles, but not my vertical dipoles. i have never
used a Magloop.

i suspect getting an antenna off the ground helps. the trees and buildings
are out of the way. does it lower the elevation angle? does it change
ground loss?

just as an example, i tried a 10 meter vertical at 100 feet. it compared
favorably with a tribander on some paths! conventional wisdom is that a
beam smokes a vertical.

Gravity

gravity wrote:
just as an example, i tried a 10 meter vertical at 100 feet. it compared
favorably with a tribander on some paths!

EZNEC will tell you why.
--
73, Cecil http://www.qsl.net/w5dxp

Lee wrote:

My homebrew 3 foot dia Magloop works very well vertically mounted 3 foot
off the ground but i`m wondering if maybe it could do a little better in
the low angle radiation department ....i seem to hear stations within
1000miles consistently strongest.....VKs and stateside etc much lower
!!!.....

The loop is mounted on a rotator above a groundmat buried about 6 inches
beneath the lawn and consists of 30 radials each about 30 foot long and
the loop is mounted in the centre, is that ok, or should i work the loop
higher than 3 feet above the mat, or remove the ground mat and work just
with medium loam soil underneath instead??........

Thanks to Cecil and others for help and advice in building the loop, it
tunes 40 thro` 15 meters......

Lee......G6ZSG.....


Lee,

Try mounting your loop horizontally instead. Look at the MFJ mag loop.

By doing so, you will have a significantly lower pattern of radiation from
your loop. You can also use a remotecontrolled LC network to change
directivity of the mag loop without a rotor. However, it's simpler with a
rotor.

To avoid skewed directivity from your loop, you can feed it with a balanced,
dual gamma match. Combined with a RF trafo with a centre tap on the
secondary side ( antenna side ) connected to the zero point at the loop,
you get a more equal pattern of radiation.

Don't bother increasing the mount unless you have electrically conductive
objects nearby. A loop does not need a groundplane.

As long as you can remotely tune and direct your mag loop, you actually have
a rather good antenna. Don't listen to much to these who have acres of land
and no neighbours but have fun making QSO's instead!


Cheers

Dan / M0DFI

wrote in message
ps.com...

Lee wrote:
Oh, the regular circular shape 10`x 0.625" tube with a `T` shaped frame
support and motor driven cap........


I assume the tubing is very well connected at the joints? Copper tube?

Yes!

What type of capacitor? How are the connections made?

Variable airspaced 12-14kv rotary supplied as a kit by local radio
company --£18.50p---

Turning the loop horizontal won't help unless you can get it up 1/4
to1/2 wave or more.

I already said that! :-)

Close to earth you are better off with vertical, and the mat will help
efficiency although it is pretty deep for higher bands.

!!!....

73 Tom


Thanks Tom.

73. Lee....de G6ZSG.....

"Dan Andersson" wrote in message
...
Lee wrote:
snip...

Lee......G6ZSG.....


Lee,

Try mounting your loop horizontally instead. Look at the MFJ mag loop.

Can`t afford the MJF on a pension besides for £50, mine works as well as the
MJF probably better as i use copper tube, MJF use aluminium!! and mine was
£350 cheaper.........

Thought about horizontal and high but the neighbours object altho` my tower
has been there before they moved in.......keeping the peace i suppose!!.

By doing so, you will have a significantly lower pattern of radiation from
your loop. You can also use a remotecontrolled LC network to change
directivity of the mag loop without a rotor. However, it's simpler with a
rotor.

Yes, once again it`s the height.

To avoid skewed directivity from your loop, you can feed it with a
balanced,
dual gamma match. Combined with a RF trafo with a centre tap on the
secondary side ( antenna side ) connected to the zero point at the loop,
you get a more equal pattern of radiation.

I`m currently feeding with a faraday loop.....

Don't bother increasing the mount unless you have electrically conductive
objects nearby. A loop does not need a groundplane.

That`s what i thought.

As long as you can remotely tune and direct your mag loop, you actually
have
a rather good antenna. Don't listen to much to these who have acres of
land
and no neighbours but have fun making QSO's instead!

Thanks.

Lee.....G6ZSG.....


Cheers

Dan / M0DFI