Some experiences from FDTD analysis of broadband phased arrays

Some experiences regarding FDTD analysis of broadband phased arrays are presented. First, a recently developed FDTD technique for unit cell analysis of periodic infinite phased arrays is recapitulated. The new technique applies to pulse excitation in oblique directions. Second, simple methods to save computer memory using a local FDTD grid in an otherwise coarse FDTD grid to model elements in finite phased arrays are examined. It is found that the local grid methods suffer from numerical instabilities. Third, the question is discussed of how large a finite broadband array needs to be in order to demonstrate low-frequency performance comparable to infinite array predictions. A considerably larger number of elements is required in the broadband case than in the normal narrowband case