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Old June 25th 06, 12:58 AM posted to rec.radio.amateur.antenna
Dan Andersson
 
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Default Magloop and ground mat blues.....

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