Active Phased Array Antenna with Self-Oscillating Harmonic Mixers

The active phased array antenna with self-oscillating harmonic mixers has been investigated. The active antenna is composed of a patch antenna receiving RF signal and a parallel feedback type oscillator which operates as the self-oscillating harmonic mixer, and down-converts the received RF signal into IF signal. The oscillator has two ports for output of the oscillated power and for injection signal so that the oscillators can be coupled unilaterally without other nonreciprocal components. In the unilaterally coupled array, the phase differences between the local oscillating signals can be varied by changing the local free-running frequencies of the self-oscillating mixers. The receiving directivity can be controlled by combining the IF signals from the individual active antennas. In the experiment using the two-element array, the receiving pattern was scanned successfully.