Circularly Polarized Antennas for Ham Radio
Grant
A circularly polarized antenna system where both the transmitting and receiving antennas are CP can provide some advantages when compared to a typical linearly polarized RF antenna circuit. The reader is cautioned that this report is long, highly technical, and requires careful study. The author hopes that the reader will be inspired to experiment with HF CP designs based on the concepts and practical examples described in this article. All EZNEC files are included.
Introduction
Circular polarization1 can be created in an antenna by exciting a horizontal element and a vertical element in quadrature.2 That is, the phase of the RF signal sent to the two physically orthogonal elements differs by 90 degrees. This creates a clockwise (right hand) or CCW (left hand) rotation. The act of splitting the signal into two quadrature components also improves system impedance bandwidth substantially. If the two radiating elements have the same impedance sweep, then back at the source one is rotated to the opposite side of the Smith chart (a quarter wavelength), thereby providing some reactance cancellation at the sidebands.
This 50 page article is
available from the author via email for $15 sent to PayPal
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