Broadband Dual-Polarized Single-Layer Reflectarray Antenna With Independently Controllable 1-Bit Dual Beams

An independently controllable dual-beam reflectarray antenna is presented using a broadband dual-polarized single-layer 1 bit unit cell. The unit cell independently provides two-state phase compensation for two orthogonally linearly polarized waves. The 180 degrees reflective phase difference between the two states is achieved by tuning the magnetic resonance of State 0 and the electrical resonance of State 1. With its two resonances close to each other, the unit cell has a reflective phase difference of 180 degrees +/- 20 degrees between two states over a broad bandwidth of 27.2-51.1 GHz. The cross-polarization levels of below -30 dB ensure the high isolation between two polarizations. Using the proposed unit cell, a fixed dual-beam reflectarray antenna is designed and excited by a dual-polarized horn to show the ability of independently controlling two orthogonally linearly polarized waves. At 33 GHz, the beams direct to 20 degrees and -15 degrees for the feeding of horizontally and vertically polarized ports, respectively. The 1.5 dB gain bandwidth is greater than 20% for both polarizations. The proposed dual-polarized reflectarray antenna proves that, for two orthogonally linearly polarized incident waves, the independently controllable fixed dual beams can be realized using the 1 bit phase compensation and single-layer structure.