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Old September 24th 04, 12:39 PM
Robert11
 
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Default Random Legth Receiving Only Ant.; Close Into A Loop ?

Hi,

New at this.

Do sw listening only (no transmitting) up to 30 MHz.
Like to listen at most all freq's.

Have a random-length simple wire strung around the 4 sides of the attic.
Same wire is fed down a floor into radio.

It's open at the end; NOT connected back to beginning of attic run to form a
loop.

I know I can try it and see, but frankly it's getting hard for me
now to crawl around up there.

Would you expect better performance if it was formed into a loop ?
Why ? (what "theory" or eq's would apply ?)

Thanks,
Bob

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Old September 24th 04, 01:05 PM
Dave
 
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i would do lots of very detailed calculations, lots of computer modelling,
and measure it with every instrument i could find to be sure it has exactly
the pattern predicted and the right impedance across the whole hf band so
the receiver would work properly. then after months of computing and
modeling and measuring i would hook it up and it would work the same as it
would work if i had hooked it up without doing any of that. a random length
wire, in close proximity to buildings with wiring and other unknown metal
stuff can not be adequetely modeled over even a small range of frequencies,
let alone 'most all freqs'. so hook it up and try it, if it lets you hear
what you want then leave it alone. if it doesn't then try adding another
wire out the window or around the floor or hook up your bedsprings.

"Robert11" wrote in message
...
Hi,

New at this.

Do sw listening only (no transmitting) up to 30 MHz.
Like to listen at most all freq's.

Have a random-length simple wire strung around the 4 sides of the attic.
Same wire is fed down a floor into radio.

It's open at the end; NOT connected back to beginning of attic run to form

a
loop.

I know I can try it and see, but frankly it's getting hard for me
now to crawl around up there.

Would you expect better performance if it was formed into a loop ?
Why ? (what "theory" or eq's would apply ?)

Thanks,
Bob



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Old September 26th 04, 03:26 AM
Peter Parker
 
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"Robert11" wrote in message
...

Would you expect better performance if it was formed into a loop ?
Why ? (what "theory" or eq's would apply ?)


I have found that this reduces low frequency pick-up. Loops need to be
approaching 1 wavelength around to work efficiently, whereas the wire would
be OK as a 1/4 wave.

As to whether the signal to noise ratio will be better with the loop - well
you'll just need to experiment ; )

73, Peter VK3YE


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