J. Mc Laughlin wrote:
Dear "Bindy"
I have blocked so many for inappropriate messages that I might have
missed the point of this sequence. However, it appears from your last
message that your goal is to use a loop antenna or loop antennas to effect
an omnidirectional pattern from 1 to 30 MHz. "True" omnidirectional
antennas do not stay that way when above ground.
If what you are wishing to accomplish is a pattern that is independent
of azimuth using a loop antenna, then a much more simple solution exists -
at least over much of the desired frequency span. A (small) loop mounted
well above ground and oriented horizontally will do the trick. For most HF
receiving purposes, well above ground might indicate a height of between 0.3
and 2.5 WL. Mounting at 30 meters will do nicely from 3 MHz to 25 MHz.
Above 25 MHz there is not much to listen to. Below 3 MHz the pattern favors
nearby stations.
Again, I am not clear about the actual problem to be solved. It is not
clear if this is an amateur application.
73, Mac N8TT
--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Bindy" wrote in message
oups.com...
Bindy wrote:
Can anyone tell me how to build a broadband hybrid combiner for 2
shortwave loop receiving antennas?
I need 45,-45 degrees of phase on the 2 loops from 1 to 30 mhz? I will
be mounting the combiner right at the antenna after the preamps.
Bindy
Thanks for all the suggestions. I pressumed it was possible. I see many
commercial antenna companies like TCI and R&S use hybrids with their
shortwave loops. I just pressumed that it was possible using small
ferrite cores. I cant find anything on google, theres d many references
to microwave hybrids.
Other phase angles might be possible, however 45 degrees ensures that
the loops when phased at right angles behave as a true omni
directional antenna from 1 to 30mhz. Which is the main reason i want to
pursue this option. I am using a MFJ 1026 noise canceller however its a
nuisance and unreliable when wanting consistent and repeatable
performance. It also cant rotate phase for the full 360 degrees.
So a fixed 45 degree hybrid would be ideal..
The search goes on
Thanks
Bindy
Hi Mac
I will be mounting my 2 magnetic loops about 2 meters or 6ft above the
ground. However the loop i am using has very sharp nulls. I believe a
45 degree phase angle will make the pattern totally omni directional.
I could run 2 cables, however hybrid would be simpler.
It seems designing a 45 degree is a tough technical challenge.
Bindy