A Series Inclined Slot-Fed Circularly Polarized Antenna for 5G 28 GHz Applications

This letter presents the design of a single point-fed, geometrically simple circularly polarized (CP) antenna for 28 GHz Ka-band applications. The proposed antenna is based on a straight microstrip line printed on one side and coupled with the nearly square patches through a 45° inclined V-shaped slot aperture on the other side. In order to generate circular polarization, the fundamental radiating mode is degenerated at a slightly different frequency by aligning the patch edges parallel to each arm of the V-slot with orthogonal arms. This configuration yields a relatively small size (10 mm × 27.7 mm), wideband, and high-gain right-hand CP antenna operating at 28 GHz. The impedance bandwidth of the proposed antenna is from 27.2 to 30.35 GHz and the 3 dB axial ratio (AR) bandwidth from 27.3 to 29.7 GHz with excellent directional characteristics in the broadside direction. The peak gain is approximately 11.65 dBic. The performance characteristics in terms of the impedance matching, AR, gain, and efficiency of the antenna for wearable applications are also investigated both numerically and experimentally. For practical applications, the small size of the structure allows for implementing the systems that consist of more than one antenna to account for user mobility.