Design of broad-band dual-polarized microstrip patch antennas with high port isolation for millimeter-wave 5G applications

Abstract

In this thesis, multiple broadband dual linearly polarized antennas are designed covering the frequency band for the next generation of 5G communications around 28 GHz. Dual polarization antennas are employed to increase the capacity of the allocated spectrum through frequency reuse. Techniques for improving the impedance bandwidth is one of the most researched areas of microstrip antenna technology. New multi-layer dual linearly polarized design topologies are proposed in this thesis, based on substrate integrated waveguide (SIW) cavity-backed microstrip antennas. Different structures and materials, and antenna types are explored. Wide impedance bandwidths of around 34% to 47% are achieved. In addition to very wide impedance bandwidth, the designs have a profile that is nearly half that of similar antennas reported in the literature without degradation to the antenna front to back ratio or radiation performance. In addition, a technique to improve the port to port isolation of the antenna by more than 10 dB is proposed. All designs proposed here achieve isolation levels above 30 dB across the band of interest. Two antenna arrays, a four - and a sixteen-element are also designed based on the single element patch and fractal antennas. Their operational bandwidth is around 21% from 24 to 30 GHz, and sidelobe levels are better than 9 dB. Simulation and optimization are carried out using full wave electromagnetic solver. A prototype of the final design was manufactured and tested. Results of all designs are compared and discussed for their bandwidth and the level of the port isolation in comparison to other millimeter wave dual linearly polarized antennas reported in the literature.