PHOTONIC BAND GAP WAVEGUIDE SIMULATION USING FETD- and FEFD- METHODS WITH MULTI-MODAL BOUNDARY TERMINATIONS

摘要

There is a growing interest in the application of photonic band gap (PBG) structures in microwave and millimetre wave engineering due to their useful frequency selective rejection behaviour that is linked to improved microwave device performance, Sievenpiper (1). PBG structures are in general geometrically complex. The finite element method is well suited in accurately modelling inhomogeneous and irregularly shaped regions and, in its frequency domain form, has been successfully applied in the modelling of photonic crystal structures. Although the Finite Element Frequency Domain (FEFD) method has often been employed to model PBG structures, Freni and Mias (2), Mias et al (3), little modelling work was done in this area using the Time Domain version of the Finite Element Technique, Cucinotta et al (4). In this paper, an FETD code employing a recently proposed, Loh and Mias (5) exact multi-modal absorbing boundary termination condition (MABTC) is applied, for the first time, to model photonic crystal structures in parallel plate waveguides. The MABTC was derived from the frequency domain waveguide modal field distributions using the inverse Laplace transform. The FETD-MABTC results are compared with those obtained from the FEFD-MABTC method, Jin (6).