A NEW PHASE-SHIFTERLESS BEAM-SCANNING TECHNIQUE USING ARRAYS OF COUPLED OSCILLATORS

A method for electronic beam scanning in linear arrays of antenna-coupled oscillators is introduced which eliminates the need for phase shifters. It is shown that a constant phase progression can be established by slightly detuning the peripheral array elements, while maintaining mutual synchronization. This unusual nonlinear behavior is explained using coupled Van der Pol equations. A stability analysis provides theoretical limitations on the achievable inter-element phase shift. When the phase of the coupling is zero, the theory predicts an inter-element phase shift that can be varied continuously over the range -90-degrees < DELTAtheta < +90-degrees, and is independent of the number of oscillators in the array. An experimental four-element planar MESFET array was built, operating at 10 GHz with close to zero coupling phase, giving a measured phase progression that was continuously variable over the range -88-degrees < DELTAtheta < 66-degrees.