Analysis And Design Of Millimeter Wave Circularly Polarized Antenna Arrays

The millimeter-wave(mm-wave)band is considered as the candidate for high speed communication services in 5G networks due to its huge bandwidth,high throughput and small interference.As an important component of communication system,the mm-wave antenna not only has the advantage of compact size and easy-to-integrate structure feature,but also can improve the practicability of mm-wave via multi-antenna technology and circularly polarization.Therefore,the research of mm-wave CP antenna array has benefit for mm-wave's applications and development.integrated waveguides(SIWs)have been widely investigated by many researchers.The structures exhibit propagation characteristics similar to those of classical rectangular waveguides with few basic differences.The technique allows to fabricate a complete circuit in planar form and integrate all microwave components on the same substrate.In this article,based on the principle of antennas and SIW,mm-wave CP antennas and SIW feed networks are developed.We also design and fabricate three SIW-fed Ka band CP antenna arrays.This article includes three parts as follows:1.A Ka band CP antenna is analyzed.The radiating part consists of a couple of openloop microstrip,an outer loop and an inner loop.The out loop is the main radiation loop,while the inner loop is a parasitic radiation loop.The outer loop is fed by a vertical probe at the end of loop.By simulation,it is found that the antenna has some good radiation characteristics.Then we designed a 2×2 antenna array in which the array element is the one we designed.All elements are excited with equal amplitudes and same phase.By simulation and analysis,we found the relationship between the distance of two elements and the radiation characteristics of the array.2.A Ka band feed network is designed.The feed network is composed of a 16-way power divider and a feeding couple element.The power divider is used for dividing the test signal into 16 parts and transmitting to antenna elements in array,while the feeding couple element is designed for coupling the test signal into the power divider.By simulation,it is found that the feed network is satisfied with the needs of array design and has low loss characteristics.3.A 30-GHz mm-wave 4×4 CP antenna array is developed by integrating the antenna and feed network we just have designed.The antenna array is fabricated by multi-layer PCB technology.The experimental results show that the radiation performances are satisfied with the design specification.An 8×8 antenna array and a 16×16 array are also developed by optimizing and adjusting the structure of the 4×4 antenna array.The operating frequency band of the antenna arrays is shifted to 28 GHz for the 5G network.The experimental results show that both 8×8 antenna array and 16×16 array have better performances than the 4×4 array,such as higher gain and narrower beamwidth.