Design of a beam-steerable microstrip line based leaky wave antenna using uniaxial field programmable microwave substrate (FPMS)

Abstract

The ever-growing wireless technologies of today are pushing the limits of the state-of-the-art radio frequency (RF) components design. One special requirement which is widely needed in modern applications is for the RF components to be smart, compact, and agile. Performance characteristics such as frequency tunability, antenna pattern reconfigurability, radiation polarization diversity etc., are the need of the hour. Field Programmable Microwave Substrate (FPMS) is a pertinent answer to the challenges of the modern wireless communication standards. Given the unprecedented level of programmability, the FPMS has the potential to affect the RF and microwave component design in a similar manner as the Field Programmable Gate Array (FPGA) affected the digital domain. The FPMS technology is composed of small unit cells that can be actively biased to control the dielectric material characteristics. Using this quality of FPMS, this work focuses on the design of a leaky wave antenna (LWA) where the uniaxial modulation of the substrate properties allows for the beam steering capabilities. The antenna is designed to operate at 2 GHz on a Duroid 5880 material system as a proof-ofconcept. First, the FPMS unit cell is optimized to operate at the desired frequency of 2 GHz with the help of a full wave solver ANSYS HFSS. Once optimized, the unit cells are integrated onto the antenna structure to study the effects on its radiation and impedance performance. A complete parametric study is performed on various design parameters to obtain the optimized impedance and radiation performance of the antenna. The low loss nature of the substrate provides for an antenna gain value as high as 11 dBi with a gain variation of 2.5 dB. A continuous maximum beam steering of backward and forward direction i.e., ±30° is achieved from the LWA design with reasonable gain values. These performance parameters of the antenna demonstrate the potential of the novel FPMS technology in the design of intelligent RF components.