Antenna dimensions are depended on the
placement and inductance of the inductor. However the inductance
of the inductor is not critical for antenna operation. Most important
thing is that the inductors have the same inductance. In my case
the inductors (measured by me) have inductance 31.4- micro Henry.
The inductance is influenced to the parameters of the antenna.
The more it is inductance of the inductor the less length of the
parts of the antenna and the less passband of the antenna.
Antenna was placed at the mast in 7-
meters height. The mast was made from a fiberglass plastic. Antenna
was made from stranded wire in plastic insulation. Antenna was
fed through 50- Ohm coaxial cable. the
I have used RG 313 type. This cable was
going along the mast and then going underground to my shack. Length
of the cable was near 20- meter.
Weather practically did not influence to the antenna.
Antenna was easy tuned to SWR 1:1 at
both Bands. Antenna had bandpass near 200- kHz (at SWR 1.5:1)
at the 20 meter Band and bandpass near 75- kHz (at SWR 1.5:1)
at the 40 meter Band. At first step the antenna should be tuned
at the 20- meter Band by symmetrical changing lengths of the parts
A. Then antenna should be tuned at the 40- meter Band by symmetrical
changing parts B. Changing the length of the parts B practically
did not influenced to the operation at the 20- meter Band.