FDTD modelling of an aperture coupled patch antenna for use in an active array

The finite difference time domain (FDTD) method of analysing active microstrip patch antennas is being used by several researchers. It is especially useful once it is necessary to include active elements within the structure. The authors´ current research is directed towards designing and modelling an electronically controlled phased array consisting of microstrip patch antennas, each fed by its own oscillator. These oscillators are phase-locked to a reference signal using the injection-locking mechanism. Using this technique, the relative phase difference between each element may be controlled quite easily, for example, by changing the free-running frequency of the oscillator. Additionally, by locking the oscillators to a spectrally pure signal, an improvement in the phase-noise of each oscillator is observed. In order to optimise the oscillators, it is important to determine the characteristics of their loads, i.e. the antenna elements