Beam Steering Using Active Frequency Selective Surface for 5G Applications

Abstract

The latest generation of cellular communications is 5G. This meets the requirements of high data rates, voice quality and desired video applications. 5G relies heavily on beam formation to maximize data rate particularly once it used to transmit and receive at mmwavelength frequencies. The steering wheel is also called the beam formation, it reduces the interference with the change in main lobe direction of the radiator. That is why the beam steering can play an important role in increasing interference immunity and achieving higher data rates at the 28 GHz 5G frequency band. Latest technique that has been used for beam steering is the use of active elements with frequency selective surface (FSS). It employs a planar source antenna and periodic or non-periodic structure array of elements arranged on a substrate. Active PRS is placed at some height above the source antenna. Active elements that are used with PRS are PIN/ Varactor diodes or MEMS switches. When PIN diodes turn On and OFF, the impedance of the surface varies. As a result, reflection/transmission magnitude and phase change that bend the main lobe of the radiating source. To increase the beam steering, a frequency selective surface is design with active elements (PIN diodes) called AFSS. It creates large reflection/transmission magnitude and phase difference when PIN diodes change the ON/OFF states. This approach is used with a coaxial feed patch antenna operating at 28 GHz with the gain of 7.5dBi. 2 PIN diodes are embedded in unit cell structure to make it active PRS for beam switching. Different ON/OFF combinations of PIN diodes provide ± 51◦, ± 95◦, ± 103◦ beam steering angles in the elevation plane and ± 42◦ in the azimuth plane. The gain of the beam steering antenna in all states are 8.5dBi, 12.17dBi, 10.07dBi and 10.6 respectively. Radiated efficiency is also varying with states. The efficiency of beam steering is 92%, 84%, 72% in the elevation plane and 81% in the azimuth plane respectively. This is a low profile and ease to fabricate, and it is useful for 5G communication networks