describing of the antennas I would like to talk why those ones
were designed. At fall 2009 the Youth Collective Radio Station
RK9QWN had to change room
inside the building. Old antennas were removed because the roof
was repaired. So it needed to install new antennas.
The question was- what
should be the antennas like?
Once night I was digging
up models of antennas bundled with Antenna Simulator MMANA –
GAL (may be loaded free, see Reference
1) and thinking
about antennas for limited space. Among butch of the antennas
I found of an interesting antenna for the 20- meter Band (model
/ANT/Match/Short-Gamma-dipole.maa from the Antenna Simulator MMANA).
It is very interesting
antenna. In Reference 2 Igor
Goncharenko treats the antenna like a limit case for shortening
dipole with gamma matching (when the gamma matching equal to the
length of the shortening antenna). At the other side it is usual
stub dipole. For future development of the antenna please take
attention that the dimensions of the antenna would be resonance
at 10- meter Band. On the base of the two antennas was designed
my antenna for two Bands- the 20 and 40- meter. Figure
1 shows design of the antenna.
MMANA file may be downloaded
and Matching of the Antenna: Antenna
has input impedance 150 Ohm at the 20- meter Band. At the Band
antenna is tuned in to resonance by the height. At the 40 meter
Band antenna is tuned to resonance by the capacitor C1 (see Figure
At the 40- meter it is possible to play with input resistance
of the antenna by changing wide between the antenna wires. C1
just compensated the antenna reactance. Relay K1 is switched ON/OFF
the capacitor that is provided the changing of the antenna Band.