Digitally Controlled GaAs MMIC Attenuator for Active Phase Arrays

Multi element arrays with active transmit-receive modules have resulted in the ability to reconfigure beam patterns and steer beams through the use of multibit phase shifters and amplitude control. The advantages of the GaAs MMIC in size, mass and reproducibility, together with negligible power consumption, are critical in the realisation of a versatile spacebourne synthetic aperture radar with the facility for reconfigurability by telecommand from groundstations. A six bit attenuator is presented, designed to cover the 4.9 to 5.7 GHz band but with excellent performance from D.C. to 6 GHz. The measured rms error for all states is 0.2dB.