Title :
Phase control of circularly polarized waves from a parasitic dipole mounted above a slot
Author :
Kyeong-Sik Min ; Hirokawa, J. ; Sakurai, Kimio ; Ando, M.
Author_Institution :
Dept. of Radio Sci. Eng., Korea Maritime Univ., Pusan, South Korea
Abstract :
A combination of a slot and a parasitic dipole is a well known element for circular polarization. The authors adopted these elements and proposed a single-layer linear-to-circular polarization converter consisting of a dipole array to be mounted on an existing narrow-wall slotted waveguide array. Unfortunately, the slots on the narrow wall in an existing array are inclined alternatively with respect to the waveguide axis. It results in an alternating phase error of the array illumination and serious grating lobes appear in the array pattern. The authors have suppressed these lobes by changing only the dipole angle at the cost of the axial ratio of the element pattern. They discuss and extract the mechanism of this novel finding. By using the simple approximation for the induced currents on the dipole, they express the amplitude and the phase of circular polarization in analytical forms. This expression clearly explains the behavior of the circular polarization. An important result is that the phase of the circular polarization is determined only by the dipole angle and is independent of that of the slot. These relations are also confirmed by experiments.
Keywords :
antenna radiation patterns; convertors; dipole antenna arrays; electromagnetic wave polarisation; phase control; slot antenna arrays; amplitude; array illumination; array pattern; axial ratio; circularly polarized waves; dipole angle; dipole array; element pattern; experiments; grating lobes suppression; induced currents approximation; linear-to-circular polarization converter; method of moments; narrow wall slots; narrow-wall slotted waveguide array; parasitic dipole; phase control; phase error; waveguide axis; Costs; Current; Educational institutions; Lighting; Magnetic analysis; Magnetic resonance; Phase control; Phased arrays; Polarization;
Conference_Titel :
Antennas and Propagation Society International Symposium, 1997. IEEE., 1997 Digest
Conference_Location :
Montreal, Quebec, Canada
Print_ISBN :
0-7803-4178-3
DOI :
10.1109/APS.1997.631821