Performance evaluation of cavity-backed slot antennas using the FDTD technique

This paper proposed feed models appropriate for the FDTD evaluation of the input characteristics of the cavity-backed slot antenna. By employing the coaxial model and the gap voltage model, we showed the coaxial model effectively reduced the amount of time steps and did not require the time window function to estimate experimental results of the input characteristics. Compared with the gap voltage model, the coaxial model gives a good estimation of the input impedance by only 3000 time steps. On the other hand, the gap voltage model and time windows required 32768 or 20000 time steps for the accurate estimation. It is concluded that the coaxial model requires only 9 % or 15 % of the time steps required for the gap voltage model. As a result, we concluded the coaxial model is effective for the FDTD analysis of the cavity-backed slot antenna. This technique is easily applicable to the evaluation of mutual coupling and beam steering performance of phased array antennas.