Analysis of electromagnetic coupling through a thick aperture in multilayer planar circuits using the extended spectral domain approach and finite difference time-domain method

Electromagnetic coupling plays a very important role in the design and development of integrated antenna arrays and microwave circuits. With the availability of accurate computer-aided design tools, proper characterization and analysis, this coupling phenomenon could be used to simplify the packaging and fabrication process, to reduce manufacturing cost, and also to add flexibility to the design of multilayer structures in many cases. An accurate and efficient spectral domain approach (SDA) is proposed as a means to study the coupling effect through an arbitrary aperture in a thick common ground plane of multilayer planar circuits. In addition, the finite difference time domain (FDTD) method is present as an alternate approach to this type of problem and also is used as a validation tool for the spectral domain method because of its simplicity, generality, and accuracy. The proposed methods are applied to different aperture coupled structures for illustration