An overview of the modelling of an active microstrip patch array

This paper presents an overview of the use of the HP-EESof Communications Design Suite software and the Finite-Difference Time-Domain (FDTD) method for the analysis of an active microstrip patch array. The use of frequency and time-domain simulation algorithms for the prediction of free-running and injection-locked oscillators is discussed. The modelling of the passive radiating part of the antenna using the FDTD method is covered. Free-running oscillators are shown to be handled accurately and efficiently using the harmonic-balance algorithm, but injection-locked oscillators are a source of difficulty. The FDTD method, when compared to measurements, gives good results for the input impedance and mutual coupling of the passive array.