A heterodyne-scan phased-array antenna

A new phased-array antenna system concept for narrow-band frequency beam st eering is introduced. The phase shift between neighboring antennas in the a rray is controlled by changing the frequency of the signal traveling along fixed delay lines in a series feed network, Diode mixers are added before e ach antenna to convert the frequency of the control signal to a constant ra diating frequency. A complete transmit system, using microstrip patch anten nas, was built on a 4 x 6 in(2) printed circuit board for an X-band demonst ration. As the control frequency was swept from 15.1 to 18.4 GHz, the beam was steered from -52 to +46 degrees with the peak power density variation o f 5 dB, mainly due to nonuniform mixer conversion loss at different control frequencies.