Interpolation locking: a new technique for active array antennas

The paper describes theory and experiments on a new technique for reducing the number of phase shifters in active transmitting antenna arrays. Alternate elements in the array have no phase shifters and are locked to the mean phase of their neighbour elements by a signal mutually coupled from the radiating apertures. The technique allows both the number of phase shifters and the required locking power to be reduced by half in an active linear array. The beam steering angle is limited to about ¿¿ 30¿¿, but steering angles up to greater than half this value may be obtained with very similar sidelobe levels to those for an array with phase shifters in each element. Very good agreement is obtained between a theory, taking into account the oscillator locking characteristics, and experiments on a 7-element X-band array of waveguide elements with impatt oscillators.