Coupled-Oscillator Phased Array Systems for Millimeter Wave Applications*

An array of oscillators coupled through mutual injection locking on a nearest neighbor basis has the property of automatically adjusting itself to linear phase progression across the array in response to appropriate adjustment of the elements at the edge of the array. This mechanism is well-suited to phase generation for phased array antennas at millimeter wavelengths because it obviates the topological complexity associated with feed and control manifolds found in conventional phased arrays. This paper discusses recent understanding gained in the operation of coupled-oscillator arrays and their exploitation for phased array antennas. COUPLED OSCILLATOR PRINCIPLES The use of phase-locked oscillators for beamsteering was proposed in 1974 by Al-Ani, et. al. [1]. The exploitation of the phase dynamics of coupled-oscillator systems to generate phase gradation across an array was first proposed by Stephan [2] and have been substantially elaborated upon by York and his colleagues [3]. A key result of [3] is a set of coupled non-linear differential equations that describe the phase dynamics of a coupled oscillator array: