A Chebyshev Approximation Technique Based on AIM-PO for Wideband Analysis

A novel hybrid method combining the adaptive integral method (AIM) and physical optics (PO) with Chebyshev approximation technique (CAT) is presented for wideband analysis of antennas in the presence of electrically large conducting platforms. In the hybrid AIM-PO method, the AIM is applied to reduce the memory requirement of the method of moments (MoM) impedance matrix and the MoM-PO interaction matrix. Significant speed enhancement is achieved by acceleration of the matrix-vector multiplications with fast Fourier transform (FFT) in MoM and PO regions. To achieve fast frequency sweeping, the CAT technique is employed to expand the unknown current coefficients into a Chebyshev series. Instead of direct point-by-point simulations, it is only necessary to calculate the currents by AIM-PO at several Chebyshev-Gauss frequency sample points. Two examples show that the hybrid technique can greatly reduce the computation time without loss of accuracy.