Designing cylindrical filtering circuits with the unconditionally stable ADI-FDTD method

As cylindrical structures, such as coaxial lines, are often used in RF or microwave systems, circuits constructed in a cylindrical form can become very attractive. A novel cylindrical planar filter is introduced and designed with the newly developed cylindrical ADI-FDTD (alternate-direction-implicit FDTD) method. It is shown that the proposed design, which can be connected easily with other cylindrical circuit structures, has better performance than its rectangular planar counterpart. It is also demonstrated that the ADI-FDTD can be applied effectively to the design of cylindrical circuit structures.