Lumped Coupled Ring Antenna Array

Arrays of coupled active antenna oscillators are used for power-combining at microwave and millimetre-wave frequencies. The mutual coupling between array elements determines the operational mode of the array and hence its far-field radiation pattern. Separately it is known that enhanced oscillator modal stability can be achieved by coupling oscillators through lumped capacitive elements. In this paper lumped element and mutual element coupling are employed concurrently. The arrangement takes the form of a ring coupled oscillator used to excite a 2×2 array whose sources are coupled by capacitive elements and whose loads, the actual microstrip patch antenna elements, are mutually coupled. In this paper the effect of these couplings are evaluated using a time domain analysis. Experimental results for a 2×2 array are presented which validate the theoretical predictions made.