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.
Igor Grigorov. Antennas. Practice of Radioamateur. – Moscow,
Antenna for 17 meters
Igor Grigorov. Antennas. Tuning and Adjustment.
RadioSoft, 2002 (In Russian)