Frequency-Selective Beam-Shaping Technique to Provide Equal Beam Coverage Using Reflectarray Antennas for Dual-Band Multispot Satellites

In this communication, a simple technique is presented for transmit/receive (Tx/Rx) reflectarrays in the Ka-band to improve the shaping of the Rx beams without altering the performance in Tx, with application to geostationary satellite communications. The technique is based on the introduction of a controlled phase noise in the reflected field at Rx frequencies by a 180° phase reversal gradually introduced in some reflectarray cells randomly distributed on the antenna. Simulations of a 1.8 m parabolic reflectarray at 19.7 and 29.5 GHz show a reduction of 2.6 dB in the roll-off factor at 29.5 GHz, with also lower sidelobe levels. The proposed solution offers a large flexibility to shape the beams by a simple method with a low computational cost that does not increase the manufacturing complexity and costs of the antenna.