COMPARISON:
Magnetic Loop
with RoomCap on 20m
30th November 2006 / 6.6.2014
Since long
time it
was my desire to compare the RoomCap antenna with a good
magnetic Loop antenna.
On November 30th 2006 this test took place.
The test was assisted by Edy, HB9EBG.
Comparing antenna = Magnetic Loop, 85cm diameter, 35 mm
diameter of
tube,
copper
tube, silver plated, with Annecke butterfly capacitor
with
remote tuning, in vertical position.
Test antenna
=
RoomCap for 20m, 5cm diameter, length of radiator =
150cm,
without
top capacity.
Both antennas were placed at the same height (150 cm
above ground) in a
free field,
using the same 100 W transceiver, and adjusted to VSWR
1:1.
In total, 13 comparing QSOs were conducted in the time
between 13.30h
to
16.00h.
In each QSO the antenna was quickly changed many times
and the remote
station
was asked to indicate the average signal strength difference between
the two antennas.
In all contacts the RoomCap was reported clearly as the
stronger
antenna, where the
smallest reported difference
was 1 S point and the largest difference was 5 S points.
Here follows the list of the reporting stations with the
indicated
difference in S points.
YO5PDW +1
LY3ZM + 3
RU6AH +1
UA3AIU + 1,5
YO3AJN + 2
EA8BRW + 2
LY2SP + 4
UR0EA + 2
YO4AAC +1
UT8NF + 1
YO6KSU + 2
UR5HDE +5
SV0XBA +2
This corresponds to an average difference of 2.11 S
points.
An S point is defined as 6 dB, resulting in about 12 dB
advantage.
(It is clear, that the receivers many times do not
follow exactly
this definition, but in the average this may be close
enough.)
PS: 12 dB = 16 x Power !
Below you see the test installation. On the left the
blue RoomCap
and on the right the magnetic loop antenna.
Felix Meyer HB9ABX +
Edy HB9EBG
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