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
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