Injection- and phase-locking techniques for beam control [antenna arrays]

Applications of millimeter-wave radar, imaging, and communication technology requires cost-effective implementation of intelligent scanning antenna systems. Injection-locking and phase-locked-loop (PLL) techniques can be used to achieve synchronous operation of a number of antenna array elements, and allow for the manipulation of the phase distribution without additional phase-shifting circuitry, suggesting a potential for low-cost beam-scanning systems. This paper describes a number of techniques, with an assessment of some remaining technical challenges for practical implementation.