Quasi-optical phase modulators

Three X-band quasi-optical transmission type phase modulators are presented: a varactor loaded grid with 25/spl deg/ continuous phase shift; a p-i-n diode loaded grid with digital phase shifts of 0/spl deg/ and 90/spl deg/; and a transistor antenna array with 0/spl deg/ and 180/spl deg/ phase states. All of the modulators operate in transmission mode and are suitable for cascading with other quasi-optical components. Relative amplitude and phase change of the transmission coefficient as a function of frequency is presented for the two digital modulators. Antenna patterns for the BPSK active antenna array modulator are also presented.