Weighted Laguerre Polynomials-Finite Difference Method for Time-Domain Modeling of Thin Wire Antennas in a Loaded Cavity

A weighted Laguerre polynomials (WLP)-finite difference method is proposed in this letter for the fast time-domain modeling of thin wire antennas in a lossy cavity. The modified telegrapher´s equations (MTE) are used to describe a thin wire antenna, and a rather fine grid is required at the feed point for accurate input impedance calculation. In that case, eliminating the Courant Friedrich Lewy (CFL) limit is important to speed up the calculation. By expressing transient behaviors of field, current, and voltage using global WLP temporal bases, a marching-on-in-degree scheme is obtained through the orthogonality of WLP bases. Without the CFL stability condition, the proposed method is more efficient than conditionally stable finite-difference time-domain (FDTD) method, which requires a large number of time-steps for computing the solution when a very fine grid is used in the spatial mesh. Simulated results are presented and discussed to demonstrate the advantages of the proposed method.