Circular Polarization-Agile and Continuous Beam-Steerable Array Antenna Using a Hybrid Design Approach

A circular polarization (CP)-agile and continuous beam-steerable array antenna is presented using a hybrid design approach. It is accomplished by combining digital reconfigurable antenna elements with analog continuously tunable phase shifters. To realize both polarization reconfiguration and initial phase generation for beam scanning simultaneously, the designed antenna element enables eight states that correspond to two CP modes with four quantized phases. The phase shifters further provide additional variable phases of −90° to 0° for antenna element excitation. Superposition of the initial and additional phases helps to satisfy full and continuous 360° phase coverage for a beam-steerable array. Meanwhile, phase decomposition also facilitates the design of phase shifters without complex or cascaded structures. By altering the bias states of the electronic components loaded in the array antenna, CP switching and beam scanning can be independently controlled. For verification, prototypes of the antenna element, phase shifter, and a four-element array are all fabricated and tested. Reasonable agreement is obtained between simulation and measurement. The resultant array could scan up to nearly ±40° off the boresight, along with stable radiation patterns and good CP performance.