Practical Measurement Parameters
of the Helical Antenna: I used a
home made RF bridge (see Reference
2) for metering of the helical. My Helical has input
impedance 35 Ohms at the 20 meters and 46 Ohms at the 17 meters.
Theoretical parameters
of the Helical: The theoretical parameters of the helical were simulated
with the Helical3 (a special program for helical antennas) designed
by R.J. Edwards, G4FGQ. On the basis of these calculation I could
assume that the efficiency of my helical is near
15- 12% (in comparison with quarter wave vertical antenna with
good grounding). I.e. my helical lose up to 9 decibels or up to
1,5 balls on scale S in comparison with
the quarter wave vertical.
References:
1.
Igor Grigorov. Antennas. Practice
of Radioamateur.- Moscow,
RadioSoft
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Helical
Antenna for 17 meters
2.
Igor Grigorov. Antennas. Tuning
and Adjustment.- Moscow,
RadioSoft, 2002 (In Russian)
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