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We present the analysis and experimental results of a beam-steering and-switching antenna array using coupled oscillators and phase-locked loops. With the use of a type-II coupled phase-locked loop array and an external reference signal, the antenna array can steer its beam by a single control voltage, reduce the beam-pointing error arising from the phase errors of the oscillator array, and hold its output frequency stably at the reference signal frequency in operation. Using a double-pole double-throw switch and a difference amplifier at the center element of the antenna array, one can switch the array radiation pattern between the sum pattern and the difference pattern. Moreover, the beam-scanning range is extended to [+ or -] 90[degrees] by properly using frequency prescalers in the phase-locked loops. The radiation characteristics of a three-element antenna array are measured to verify the array performance. Index Terms--Antenna arrays, beam steering, beam switching, coupled oscillators, phase-locked loops.

The analysis and experimental results of an antenna array using injection locked coupled oscillators with self-tuning of oscillator free-running frequencies are presented. With the use of coupled type-II phase locked loops for tuning oscillator free-running frequencies and an external injection signal for stabilizing the array operating frequency, this antenna array can steer its beam through a single control voltage and hold its output frequency at the injection signal frequency in operation. In addition, its beam-pointing error arising from phase errors in coupled oscillators can be reduced and the array works well over a certain frequency band. Phase dynamics and stability are studied and experimentally verified. Experimental results of a three-element injection locked coupled oscillator array show that its uniform phase progression ranges between -16[degrees] and 52[degrees], and the phase errors are less than 5[degrees] at 2.7 GHz. The operation bandwidth is shown from 2.68-2.72 GHz. By loading the injection locked coupled oscillator array with rectangular patch antennas, the beam-steering radiation characteristics are measured at various control voltages. Index Terms--Coupled oscillators, injection locked oscillators, phase locked loops, stability.