"Reg Edwards" wrote in message
...
The intermod performance of a receiving pre-amplifier is of no
consequence with a magloop.

The Q and selectivity (of the order of 1000) of the loop at the wanted
frequency easily reject local high-power MF broadcast frequencies.

On 160m, It's difficult to hear any stations only 3 kHz away from the
wanted frequency.
----
Reg.


Hi Reg....

I took my little 1 meter dia ( 10 ft circ ) loop outside lunchtime and
mounted it verticaly 2ft off the lawn and tested it, not expecting anything
special and found that comparing it to the G5RV that there was no noticable
difference between the two!!...my friend and i switched out our preamps and
attenuator in.

I even turned the loop face on and edge on with a change of 2-3 S points..
So, needless to say, i am rather impressed with the performance and
bandwidth of 2:1 SWR about 180k.....so much so that i am thinking seriously
of going for a 20 ft circumference or larger for 80 and 40 metres....

Regards.

Lee....G6ZSG.....Well impressed!!! :-)

Hello Lee,

Thanks for letting me know that by giving your magloop half-a-chance
it performs according to expectations.

You have also demonstrated that the G5RV is not so hot as it is made
out to be by salesmen and they who have never tried anything else.

No disrespect intended to G5RV himself, now deceased, who claimed only
that it had a nice radiation pattern on 14.15 MHz which enabled him to
work both Europe and North America from South America without having
to climb ladders and change anything.

The magloop is by far the most efficient of all the antennas of
roughly the same physical size. Both theoretically and in practice. It
will do even better if you can get it well above ground in the
vertical plane.

In the horizontal plane it works best at the higher heights, above
surrounding obstructions like buildings. But in such surroundings
there is room to erect full-size dipoles anyway, which will obviously
do better still.

The main disadvantage on the 160 and 80 meter bands is the size,
physical and capacitance-wise, of the variable tuning capacitor. You
need a vaccuum capacitor of about 1000 pF max. By correct choice of
loop dimensions and minimum capacitor setting the 40 meter band can
also be covered. On 40 meters a small magloop can be highly
efficient. Investigate using program MAGLOOP4.

Are you using the small internal coupling loop, about 1/5 diameter of
main loop, to match to a 50-ohm feedline? This is the best and most
simple way to go,

A different ratio small loop diameter is needed for other feedline
impedances. The circuit behaves as if the turns ratio on a
transformer is being changed.

Let us know how your experiments proceed.
----
Reg, G4FGQ.

What about a fractal magloop Reg? Should be even smaller. :)

"Reg Edwards" wrote in message
...
The magloop is by far the most efficient of all the antennas of
roughly the same physical size. Both theoretically and in practice. It
will do even better if you can get it well above ground in the
vertical plane.

What about a fractal magloop Reg? Should be even smaller. :)

This is a case of a fractal GUARANTEED to perform worse than the basic
antenna in all respects.

That is unless a simple circle can be considered to be a
zero-zero-order fractal.

"Reg Edwards" wrote in message
...
Hello Lee,

Thanks for letting me know that by giving your magloop half-a-chance
it performs according to expectations.

You have also demonstrated that the G5RV is not so hot as it is made
out to be by salesmen and they who have never tried anything else.
snip

Well, for me Reg, the halfsize G5RV was the only multi band antenna that i
could squeeze into my garden...and the bandwidth of the loading coils for 80
is below my expectations..... that`s apart from the fact the loading coils
knocked out 40...ho-hum time for a better antenna that isn`t an
eyesore...and works better as a bonus.....
On VHF, beams and quadloops are no problem for 6m even, but HF is a whole
new ballgame....had i the space, i would continue with quadloops for
HF....but!!!......(shakes head).

Are you using the small internal coupling loop, about 1/5 diameter of
main loop, to match to a 50-ohm feedline? This is the best and most
simple way to go,

No. i`m using a `gamma` match, if you can call it that....the matching loop
comes next.
Wonder if a coaxial gamma match would work as i`m a staunch
believer....(could put that principle to use for the capacitor tuning
instead of a butterfly variable......)
Can`t get on with other types of loading, too fiddly!.

Regards....

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



A different ratio small loop diameter is needed for other feedline
impedances. The circuit behaves as if the turns ratio on a
transformer is being changed.

Let us know how your experiments proceed.
----
Reg, G4FGQ.

Hi Lee,

I'm a little confused about the bandwidth that you're getting. Maybe it
can be attributed to losses which widen the SWR bandwidth. That's not
necessarily a bad thing. I have used an AEA IsoLoop antenna that is
about the same size as your loop antenna but has a low loss butterfly
capacitor for tuning 10-30 MHz. On 20 meters the bandwidth is only about
20 or 30KHz(can't remember exactly since I haven't used it for a couple
of years). It works great if you park yourself on a frequency but it is
a pain to use for hunt and pounce.

Besides the null using vertical polarization, is it possible that for
your local friend you may have been cross-polarized. Usually direct wave
cross-polarization is on the order 20db which accounts for the 2 to 3 S
units of change from vertical to horizontal.

Have fun with your new toy!

73 LT

Hi Reg....

I took my little 1 meter dia ( 10 ft circ ) loop outside lunchtime and
mounted it verticaly 2ft off the lawn and tested it, not expecting
anything special and found that comparing it to the G5RV that there
was no noticable difference between the two!!...my friend and i
switched out our preamps and attenuator in.

I even turned the loop face on and edge on with a change of 2-3 S
points.. So, needless to say, i am rather impressed with the
performance and bandwidth of 2:1 SWR about 180k.....so much so that i
am thinking seriously of going for a 20 ft circumference or larger for
80 and 40 metres....

Regards.

Lee....G6ZSG.....Well impressed!!! :-)

"LT" wrote in message
...
Hi Lee,

I'm a little confused about the bandwidth that you're getting. Maybe it
can be attributed to losses which widen the SWR bandwidth. That's not
necessarily a bad thing. I have used an AEA IsoLoop antenna that is
about the same size as your loop antenna but has a low loss butterfly
capacitor for tuning 10-30 MHz. On 20 meters the bandwidth is only about
20 or 30KHz(can't remember exactly since I haven't used it for a couple
of years). It works great if you park yourself on a frequency but it is
a pain to use for hunt and pounce.

Yes, of course that should have read 2.5 : 1 SWR which is better than my
`loaded` half size G5RV on 80 at about 100kcs 2.5 : 1 SWR.......

Besides the null using vertical polarization, is it possible that for
your local friend you may have been cross-polarized. Usually direct wave
cross-polarization is on the order 20db which accounts for the 2 to 3 S
units of change from vertical to horizontal.

My `friend has a quarter wave vertical for 20 and the loop was physically
vertical ....also, my G5RV is sloping......

Have fun with your new toy!

Thanks, i am...... ;-)

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


73 LT
snip

On Sun, 02 Oct 2005 05:47:46 GMT, "Lee"
wrote:


Yes, of course that should have read 2.5 : 1 SWR which is better than my
`loaded` half size G5RV on 80 at about 100kcs 2.5 : 1 SWR.......

What is a "'loaded' half size G5RV"?

Googling for info, I see a few suppliers with loading coils for a half
size G5RV (complete with instructions), but could not find an article
with physical dimensions and loading coil characteristics.

Is this a "proprietary" antenna, not open to independent analysis.

In its "normal" mode, a (full size) G5RV has feed system losses on
160m like cricket scores. Intuition suggests that a half-size G5RV
(where everything is scaled to 50%) will have similarly appalling
performance on 80m.

Has anyone seen details of the loading coils for this "loaded
half-sized G5RV', or models of its performance?

Owen
--

On Sat, 01 Oct 2005 13:42:40 GMT, "Lee"
wrote:


I took my little 1 meter dia ( 10 ft circ ) loop outside lunchtime and
mounted it verticaly 2ft off the lawn and tested it, not expecting anything

Did your "little loop" grow since your first post... it was 1m in
circumfrence in the beginning?

Owen
--

"Owen Duffy" wrote in message
...
On Sat, 01 Oct 2005 13:42:40 GMT, "Lee"
wrote:


I took my little 1 meter dia ( 10 ft circ ) loop outside lunchtime and
mounted it verticaly 2ft off the lawn and tested it, not expecting
anything

Did your "little loop" grow since your first post... it was 1m in
circumfrence in the beginning?

Owen
--

You`re right Owen, i did state that didn`t i?...it was a typo of course,Heh
heh, it should read "10Foot circumference approx 1 meter dia".......

Thanks for telling me ......

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