Three dimensional cylindrical coordinate finite-difference time-domain analysis of curved slotline

A curved slotline is analyzed in three dimensional cylindrical coordinates using the finite-difference time-domain (FDTD) method. A modified dispersive boundary condition is utilized in the computation which alleviates the instability problem associated with the conventional dispersive boundary condition. This improves the accuracy of the results greatly. Computational results for the slotline dispersion characteristics of different substrates, slot-widths and radii are presented, discussed and compared with those obtained from closed form formulas for a straight slotline