Circularly Polarized Complementary Antenna With Tilted Beam Based on Orthogonal Dipoles

A novel design approach to circularly polarized (CP) complementary antenna with a tilted beam is proposed. First, an operational principle of the proposed antenna is theoretically analyzed to explore the relationship between a pair of orthogonal complementary dipoles. It is demonstrated that two 8-shaped patterns are generated in the elevation plane while the CP characteristic can be realized where they are overlapped with each other. Then, a CP tilted beam can be obtained by reinforcing one direction while suppressing the remainders. Finally, prototype antennas, mainly consisting of a planar conical monopole, a loop antenna, and an L-shaped ground plane, are designed and fabricated for an experimental validation. Measurement results show that a 3 dB axial-ratio bandwidth of 6.19% at θ = 30°, φ = 90° is obtained by the design approach, as well as a low complexity and stable radiation pattern.