ANTENTOP- 01- 2011, # 015

Multiband Vertical Stub Antennas

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.

Dimension 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.

References:

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, "Radio", 2006.

3. Roman Sergeev: 8- Band Asymmetrical Dipole Antenna- Moscow, Radio, 2008

4. Semichev B: Ferrite RF transformers- Moscow, Radio, 2007. # 3, pp.: 68- 69.

5. http://cqham.ru/ant78_71.htm

73! Roman Sergeev (RN9RQ)

www.antentop.org

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