Omega matching network is tuned to the
resonance with help of C1 and C2. At power up to 100-Wtts capacitors
C1 and C2 may be used ceramic ones. For high power (more the 100-Wtts)
it should be used high quality capacitors. There are: air variable
capacitors with gap more the 1-mm, lengths of a coaxial cable
having the needed capacity or just fixed high voltage capacitors
having high reactive power.
Parts of the matching networks (L and C)
were placed inside a plastic box. Radials are placed above the
heat insulation of the roof. Radials should have a plastic insulation
(with good insulation of the ends) if these ones would be contacted
with stuff of the roof. Figure
2 shows the design of the antenna.
vertical was fixed to the roof beams. No
were used for the fixing of the vertical.
through the roof (where the vertical is
on) was water proofed. However,
for the installation of the vertical at
another roof may differ from mine. So, guys
the fixing of the vertical and hard
of the hole may be needed.
Tuning of the antenna made to minimum SWR at the center
of the working band. At the 14-MHz the tuning is made by C1-C2.
At the 21-MHz the tuning is made by the lengthen
inductor. It needs to choose numbers of coils or by changing of
the physical dimension of the inductor. Since the antenna is tuned
to 21-MHz no additional tuning needed at 7-MHz.
The antenna was compared with I.V. No difference at
local (up to 2000-kms) contact. The vertical beat an I.V. at DX-
at distance more the 5000-kms. At the distance the vertical gave
1-1.5- points at S-Scale at reception and 1.5- 2 points at scale
“S” at transmitting.