Figure 3 Vertical Stub Antenna for 40, 20,
15 and 10- meter Band
The antennas may
be installed at height near one meter above the ground. Resonance
counterpoises should be used at this placement.
of the antennas should be slightly corrected if installation at
more the one meter above the ground is planned. Figure 4 shows antenna from Figure 1
that is recalculated for free space.
MMANA file may be downloaded from: http://www.antentop.org/015/ ant_4.maa
Described above antennas
may be made from strand copper or aluminum wire in diameter 1.5-
2.0- mm (15- 12- AWG).Wire in plastic insulation may be used as
well however the antennas size should be decrease approximately
on 2.4% because shortening coefficient of the wire.
Below there are several
words about feeding of the antennas.
I suggest do matching
of the antennas with coaxial cable with help of transformer on
ferrite tubes, so called “binocular transformer.” It is possible
to find lots stuff about the “binocular transformer.” I suggest
References 4 and 5.
Figure 4 Vertical Stub Antenna for 40 and
20- meter Band calculated for free space
Transformer may be installed straight
away at antenna terminals and use coaxial cable to feed the antenna.
Antenna may be fed by two wire ladder line and the transformer
may be installed at the shack.
1. Antenna Simulator MMANA- GAL
(try Google engine for best result)
2. Igor Goncharenko: HF and VHF antennas. Part II. Fundamentals
and Practice – Moscow, : Radiosoft,
magazine "Radio", 2006.
3. Roman Sergeev: 8- Band Asymmetrical Dipole Antenna – Moscow, magazine
4. Semichev B: Ferrite RF transformers – Moscow, magazine Radio,
2007. # 3, pp.: 68- 69.
Roman Sergeev (RN9RQ)