Building a Larger AM Loop Antenna for the Radiosophy
"HD100" Radio to capture more of the 1% Digital Signal
beyond the 10mv/m Contour of an AM Radio Station
{How To - Listening to "HD" Radio in the Fringe Areas}
ABOUT - The standard (OEM) little AM Loop Antenna
that comes with the Radiosophy "HD100" Radio and
is UN-TUNED : It Measures 4.25"x5" and has Six-Turns
(6-T). Using the "AM Loop Antenna Calculator"
-by- Bruce Carter
This would result in aproximately a 11.2 uH Inductance;
with 8 Feet of Wire in the Windings.
To create a bigger UN-TUNED AM Loop Antenna with
a Larger Signal Capture Area I used a 23" Hula
Hoop as a Tubular Form to hold the Turns of Wire.
Again using the on-line "AM Loop Antenna Calculator"
A Two Turn (2-T) Loop Antenna would be about 8.1 uH
of Inductance; with 12 Feet of Wire in the Windings.
- - - Experience with Loop Antennas has taught me
it is always better to start with a few 'extra' Turns
and 'trim-down' to find the better 'practical-answer'
to Loop Antenna "Sizing" mainly due to the Distributed
Capacitance of the Turns-of-Wire within the Loop Antenna
Element and other minor factors.
Empirical Testing {Trial-and-Error} Results :
[ With Respect to the smaller OEM AM Loop Antenna ]
* Five Turns (5-T) was "So So" about the same
as the smaller OEM AM Loop Antenna
* Four Turns (4-T) was Fair - slightly better
* Three Turns (3-T) was Good - much better
* Two Turns (4-T) was Fair - slightly better
So I settled on a Three Turn (3-T) Loop Antenna
Element. [ What Works . . . WORKS ! ]
According to the "AM Loop Antenna Calculator"
A Three Turn (3-T) Loop Antenna would give 16.3 uH
Inductance; with 18 Feet of Wire in the Windings.
The difference in size between the 'original'
OEM AM Loop Antenna and the new Hula Hoop AM
Loop Antenna -with respect to- Signal Capture
Area was 21 Sq In -vice- 415 Sq In about 1:20 :
The new Hulla Hoop AM Loop Antenna should
yield about 4 Times the Signal as the 'original'
and may be a 1 to 2 S-Unit improvement in the
Signal seen by the Radio.
iane ~ RHF
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