Numerical simulation of near field characteristics for lens antenna by hybrid FDTD-PWS method

An efficient hybrid Finite-difference time-domain (FDTD) method and Plane wave spectrum (PWS) method is presented to analyze the near field characteristics of lens antenna. Firstly, the aperture plane field distribution is obtained by the FDTD method. Secondly, the PWS method is employed to calculate the near field distribution from the knowledge of the aperture plane field distribution. In order to demonstrate the accuracy of the proposed method, a lens antenna at Ka band is designed and fabricated as an example. For comparison, a horn antenna and a lens antenna without outer lens are simulated to evaluate differences among the lenses on focusing properties. And the focal plane field is measured by the Planarnear-fields (PNF) method. It is found that the results obtained by the FDTD-PWS method are in good agreement with the experimental data after the probe compensation.