Millimetre-wave antenna with tilted beam for future base station applications

Abstract

A novel flexible and reconfigurable pattern antenna, integrated with an artificial magnetic conductor (AMC) surface, operating in the 29-31 GHz millimetre-wave frequency band, is proposed. The designed antenna is a modified Yagi-Uda antenna that uses as directors loop diamond shapes, allowing the bending of the structure in an easy way at high frequencies. The AMC structure is also composed of an array of diamond loops, printed on a grounded dielectric substrate without vias. Furthermore, an equivalent circuit model that allows the estimation of the resonant frequency and reflection coefficient phase of the AMC is presented. Using a flexible substrate in designing the proposed AMC antenna, different beam-tilting angles can be obtained. Moreover, multiple pattern configurations are studied. The performance of the proposed AMC antenna is measured for flat and curved configurations. The maximum beam-tilting angle is obtained for the curved AMC antenna configuration and is equal to +32° towards the +z direction with a realised gain of 12.1 dBi. Additionally, a beam-tilting in the ±z elevation plane is achieved by integrating a single pole, double throw switching system. This method eliminates the complex steering system that uses phase shifters, which is traditional for the targeted applications.