A fast near-to-far-field transformation in body of revolution finite-difference time-domain method

We present an efficient near-to-far-field transformation technique to be used in conjunction with the body of revolution finite-difference time-domain (BOR/FDTD) algorithm. The efficiency is gained by factoring out the azimuthal angle φ from the two-dimensional (2D) far-field integration using an analytical approach, thereby reducing the 2D integral on the surface of the Huygens´ box to a 1D version in the process. To illustrate the application of the proposed algorithm, the Potter horn is analyzed. The numerical results show good agreement with those obtained by using either analytical (where possible), or 2D integration schemes.