Circularly Polarized 2 Bit Reconfigurable Beam-Steering Antenna Array

In this communication, a circularly polarized (CP) reconfigurable 2 bit antenna array is proposed for beam-steering applications. The proposed antenna array utilizes a novel CP reconfigurable 2 bit patch antenna as radiation element. For a reconfigurable 2 bit element, there should be four phase states (i.e., 0 degrees, 90 degrees, 180 degrees, and 270 degrees). In the proposed radiation element, a corner truncated microstrip patch antenna is presented for CP radiation. Owing to the symmetry of the patch antenna, the 0 degrees and 180 degrees phase states are achieved by selecting feeding points of the patch instead of using complex feeding network. A 90 degrees digital phase shifter is cascaded to realize the 90 degrees and 270 degrees phase states for the 2 bit reconfigurable element. Based on the novel 2 bit CP element, an eight-element CP reconfigurable 2 bit antenna array is fabricated and tested to verify the design strategy at 3.65 GHz. The measured results match well with simulation. By appropriately controlling the ON and OFF states of p-i-n diodes, the proposed CP array can be steered from -49 degrees to +49 degrees.