"dxAce" wrote in message
...
|
|
| bpnjensen wrote:
|
| Telamon wrote in message
...
| In article ,
| (bpnjensen) wrote:
|
| (RHF) wrote in message
| . com...
|
| BJ,
|
| I would venture to say 'if' you are using the Loop Antenna for
both
| Receiving and Transmission then a 1:1 or 2:1 Balun would work well
| with a Coax Cable Lead-in-Line. An Antenna Tuner would be
required
| for Multi-Band operation.
|
| "IF" the Loop Antenna is going to be used as a Receive "Only"
| Antenna with a Coax Cable Feed-in-Line; then a 4:1 or even a 9:1
| Balun could be used with good Multi-Band results.
|
| ~ RHF
|
| Thanks RHF, and everyone else too - these are great ideas and links.
| I have managed to obtain quite good results on most of the bands
from
| 6 MHz and up, and so I was going to concentrate my efforts with this
| loop on the tropicals. I was going to start with about 220' of wire
| in a loop around my rooftop and off into some backyard trees.
|
| Based on what I've seen here and on the websites, it looks as though
| a 2:1 balun might be perfect, but a 4:1 may work about as well for a
| slightly broader frequency coverage on a receive-only antenna; so I
| may try these two first and then compare. One website says not to
| use a balun at all (why?), so maybe I'll try it unmatched too.
|
| The impedance changes according to the length of the loop relative to
| the wavelength received. A full wave length loop within a wavelength
of
| ground is around 100 ohms so you would want to use a 2:1 BALUN to 50
| ohm coax. If the loop is closer to half wave length then it will be
| closer to 50 ohms and you would want to use a 1:1 BALUN.
|
| Thanks for this, Telamon - I intend to use this antenna for reception
| only on several lower frequency HF bands (really about 3 through 6
| MHz), so I'm not sure that I want or need a BALUN/transformer that
| will match the impedance so closely. Ultimately, I may end up
| extending the length of the wire up to 340 feet and making it's shape
| weird so that it will fit in my limited space, just to see if I can
| achieve better results on 90m...but it weould still be used on 49, 60
| and 75.
|
| It has been my experience in years past that horizontal loops are great
for close in work, say on 160, 75 and 80 meters. However, they do not seem
to
| support long haul DX. And that is why many amateur users of those bands
love them, makes for a great, close in range signal, firing up, and then
down.
|
| Yes, great for reducing QRM sources, but that is because they concentrate
on vertically arriving signals, rather than the more commonly horizontally
| polarized QRM.
|
| Now, if you had the loop in the vertical plane, that would of course
change things dramatically.
|
| Just my opinion, of course.
|
| dxAce
| Michigan

From the FWIW Department, John Devoldere believes higher - angle
angennas (esp. quarter - wave verticals) outperform low - angle antennas
for greyline work, on the lower HF bands. Of course, that's only 30
minutes of a given day.

73,

Steve Lawrence
KAØPMD
Burnsville, Minnesota

"If a man wants his dreams to come true then he must wake up."
- Anonymous


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