| Microstrip line to microstrip line coupled through a circular waveguide as well as mutual coupling analysis between microstrip patch antennas on a grounded-dielectric and biased-ferrite substrate are simulated with the Finite-Difference Time-Domain method (FDTD). The open, computational-domain volume is truncated with Mur's first order absorbing boundary condition. The FDTD simulation results for both the antennas and for the transition are compared with both simulations from the Spectral Domain Moment Method (SDMM) and experimental results. These comparisons are shown to validate the FDTD program. Two major emphases are made in this work. First, a wide-band, low-loss, microstrip-line-to-microstrip-line-through-circular-waveguide transistion is achieved by varying structural parameters of waveguide length, relative dielectric permitivity in the waveguide, and the stub length. Second, the mutual coupling between microstrip patch antennas on a ferrite substrate with an externally applied dc magnetic field is modeled as a function of applied bias. As a limiting case of the ferrite substrate, antennas on a dielectric substrate are modeled. |
