Antennas from here were designed and optimized by Igor
Zel'din, UR5LCV, and design of the antennas
were wrote in the book: HF- Antennas- 3, by I. Beketov,
UR4LTX, I. Zel'din, UR5LCV, Kharkov, 1994.
10 years has gone from the publishing of the book,
for this time lots of these antennas became well- known to hams
of the CIS. Lots of these antennas are practically made and
have shown full conformity to the theoretical parameters.
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The antennas are designed for tubes of 25-mm diameter.
If for tubes with different OD are used for elements of antennas
do correcting of antenna sizes by modern Antenna Simulation Program.
Input resistance of the antenna is much lower the 50 Ohms so it
need to use a gamma match feed the antenna.
You may calculate a gamma- match using programs given at Appendix
to ARRL-Antenna Book, 19 or 20 Edition.
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4-el YAGI for 28-MHz
F, MHz
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28.0
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28.35
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28.7
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G, dBd
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7.16
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7.49
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7.87
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F/B, dB
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20.35
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28.36
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20.27
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Z, Ohm
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30.4-j7
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26.4+j1.6
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20.4+j.14.3
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SWR
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1:1.63
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1:1.14
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1:1.6
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OD 25-mm
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Reflector
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Driver
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Director 1
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Director 2
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Length, cm
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535
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503
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479
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448
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Spacing to
Reflector, cm
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0
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168
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368
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683
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