Injection signal controlled active phased arrays without mode jumps

An examination is made of phased array operation, by injecting signals with different phases into both ends of a coupled microwave oscillator system and controlling that phase, as a system for an active phased array antenna using frequency locking. This system has multiple operating modes, but by causing a slight deviation of only the free-running frequency of the end oscillator from the frequency of the injection signal, mode jumps can be suppressed and the phase difference between the oscillators made large. The effectiveness of this method can be numerically confirmed by finding the conditions for single mode operation with an approximation analysis of the governing equation. Using an active integrated antenna constructed of a patch antenna and serial-feedback FET oscillators, an experiment was performed by scanning the radiation beams of two-, three-, and five-element antenna arrays to demonstrate that the scan range in the radiation direction was extended with single mode operation. (C) 2007 Wiley Periodicals, Inc.