COMPARISON: Magnetic Loop
with RoomCap on 20m
30th November 2006
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
copper tube, silver plated, with Annecke butterfly capacitor
with remote tuning, in vertical position.
= 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
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
In each QSO the antenna was quickly changed many times and the remote
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.
LY3ZM + 3
UA3AIU + 1,5
YO3AJN + 2
EA8BRW + 2
LY2SP + 4
UR0EA + 2
UT8NF + 1
YO6KSU + 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.)
Below you see the test installation. On the left the blue RoomCap
and on the right the magnetic loop antenna.
Felix Meyer HB9ABX +