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Old December 7th 06, 08:01 AM posted to rec.radio.shortwave
RHF RHF is offline
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Default Loop antenna question


On Dec 6, 1:10 pm, "Steve" wrote:
Time to liven things up in here!

My intuition is that a modest sized, untuned, unamplified loop, fed
with a matching transformer, should be quieter and yield a better S/N
ratio than an amplified loop--even when the amplifier is itself very
'clean'. However, my attempts to build an unamplifed loop that is
quieter than--or even as quiet as--my Wellbrook suggest otherwise. Why
is this? Why doesn't an unamplified loop beat an amplified loop every
time when it comes to S/N ratio, assuming of course that it's large
enough to gather a healthy amount of signal to begin with? I'm
especially puzzled by this in light of the fact that the Wellbrook
appears not to be shielded in any way (or at any rate, that's what I
gather from a previous thread on that topic).

Steve


Steve,

Take a piece of 300 Ohm TV type Twin-Lead that
is positioned on the Wall near the Ceiling as an
Around-the-Room Loop Antenna Element.
[ 8 to 15 Foot Square Room = 32 to 60 Foot Loop ]

TIP - An Out-Side mounted Horizontal Loop Antenna
Element would be better - Space permitting.
[ 15 to 30 Foot Square = 60 to 120 Foot Loop ]
- - - Mounted 8 to 16 Foot above the ground.

Use a 300 Ohm to 75 Ohm TV type Matching
Transformer along with a piece of 75 Ohm Coax
Cable for a feed-in-line to the Radio.

Try the 300 Ohm TV type Twin-Lead in a few
different "Loop" hook-up configurations :
* Twin {Parallel} Loops ~ 40-50 Ft
* Single {Series Dual} Loops ~ 80-100 Ft
* Opposing {L&R} Circular Dipole Arms ~ 80-100 Ft T2T

While it may be eaiser to find a Noise Free Location
for the smaller Wellbrook Loop Antenna Element :
Ensuring that all parts of a larger Loop Antenna
Element are away from sources of Noise may be
more difficult to accomplish within the limited space
that we have to work within most back yards.


iane ~ RHF
 
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