In my native city Archangelsk my house is located very
close to the Power Transmission Line. High noise from the line
forced me to use Magnetic Loop Antennas. The antennas could work
very effective and may eliminate the electrical noise. I can make
QSOs with EU and JA (at 10- 18- MHz) using only 4-watts with the
Magnetic Loop Antenna. But... Magnetic Loop Antenna has some disadvantage
for me. It is a narrow pass-band (I need tune the Loop across
the amateur band). My variable capacitor at the Loop is sparked
at power close to 5-watts (that is way I used to only 4-watts
with the Magnetic Loop).
In one of the lucky day I have read article about the
UA6AGW Antenna. The antenna straight away attractive my attention
Antenna takes small room. So I may place it instead my
Magnetic Loop Antenna
Pass Band of the antenna is 150- 200- kHz. So, I do not
need retune the antenna inside the working Band.
The horizontal wires are lowered the RF-Voltage across
the variable capacitor. That should be no sparking at the variable
The three above mentioned factors were main point to
make the antenna. For making the antenna I used a length of a
75-Ohm coaxial cable in diameter 13- mm. To turn the antenna in
rigid design the length of coaxial cable was hid inside a plastic
Hula- Hoop that had diameter 80- cm. Figure
1 shows the schematic of the antenna for
the 10 and 14- MHz.
Picture 1 Antenna UA6AGW for 14 and 18- MHz Installed at my
I used usual variable capacitor (12- 495- pF) from
an old radio as C2. Usual variable capacitor 10- 70-pF was used
as C1. Horizontal wires were made from a multicore copper wire
in diameter 3- mm. Antenna for testing purpose was installed inside
of my room. Picture
1 shows the antenna in my room. Antenna
was tested at 18 and 14- MHz Bands. The length of the horizontal
wires for the bands was 2.5- meter.
away I noticed that in comparison with old Magnetic Loop (made
from the same coaxial cable) the antenna UA6AGW worked better
on to reception. And it is no sparking at the variable capacitor
at 5-watts RF-power. I used to an old surplus military radio R-143
that fed by 12- Volts. At the voltage the radio gives no more
the 5-watt output power.