Hsu Jui-Pang

Equivalent network for rectangular-waveguide H-plane step discontinuity-multi-transmission line and multi-port ideal transformer

Equivalent network for H-plane step is derived from modal analysis and expressed by multi-port ideal transformer or vector notation. Vector notation of equivalent network for waveguide was proposed. Then, whole equivalent network for step discontinuity is given. These conclusions are consistent with conventional results and help one to understand mode behavior at step. Finally, an equivalent network for various H-plane waveguide circuits is derived.

Hexagonal symmetry of magnetic field dependence of Josephson current through triangle shape superconducting junctions

We have found hexagonal symmetry in the dependence of Josephson current of triangle shape junctions upon external magnetic field. Niobium/aluminum-oxide/niobium junctions are fabricated using magnetron sputtering of niobium and thermal oxidation of aluminum layers. Selective niobium anodization process has been used to define junction areas. In the case of square shaped junction, dependence of Josephson current obtained by two dimensional scanning of the external field parallel to aluminium-oxide layer, have become the product of the two Fraunhofer patterns in the direction Hx, Hy parallel to each edge of this square junction area (1). Sub peaks have been observed in four directions at 0, 90, 180 and 270 degree around the main peak in the centre of the (Hx, Hy) plane of the Ic-H (Hx, Hy) dependence. We have also fabricated triangle shaped junctions and obtained the magnetic field dependence of Josephson current, where sub peaks can be observed in six directions at 0, 60, 120, 180 240 and 300 degree around the centre of the (Hx, Hy) magnetic plane. This magnetic dependence has hexagonal symmetry. We also simulated the dependence assuming the uniform current flow in the junction area. The gauge-invariant-phase-difference between the two superconducting electrodes is modulated perpendicular to the external magnetic field direction inside the barrier region, where the modulation wavelength is inverse proportional to the magnitude of the applied magnetic field. Quite excellent agreement between the measured data and the simulation result has successfully been obtained. (1) Akiyoshi Nakayama, Susumu Abe, Tatsuyuki Morita, Makoto Iwata, and Yusuke Yamamoto, IEEE Trans.Mag., Vol.36, No.5, pp.3511-3513, Sep., 2000

Analysis of stripline T-junction with rectangular cut based on eigenmode expansion method and Foster-type equivalent network

A stripline T-junction with a rectangular cut at the symmetric center is analyzed based on a two dimensional (2-D) planar circuit model, mode theory and the derived Foster-type equivalent network. Wide-band frequency characteristics are calculated with cut-size as a parameter, which leads to a discussion about transmission vs bandwidth characteristics, the realized limit of characteristics and determination of the optimum cut.

A novel photonic crystal bandpass filter using degenerate modes of point-defect microcavity for terahertz communication system

A novel type of dual-mode square lattice photonic selectivity narrowband bandpass filters in the terahertz communication system. In order to design a high quality factor Q microcavity, the photonic bandgap is firstly calculated by using the PWE method. Secondly, the eigen-frequencies and EM fields of a point defect microcavity generating localized states in the bandgap are calculated by a supercell method. Finally, the property of mode separation of degenerate modes is investigated for photonic crystal point-defect microcavities and proposed dual mode bandpass filters are studied by TD-BPM and full-wave time-domain method.

Field Analysis of 3-D Optical Waveguide Step Discontinuity by Equivalent Network of Multi-Transmission Line and Multi-Port Ideal Transformer

Exact analysis of 3-D optical waveguide step discontinuity is important for exact design of optical integrated circuit. In order to treat this problem systematically, equivalent network approach for lateral direction and waveguide direction is proposed and practically applied to strip-loaded 3-D optical waveguide step discontinuity with fruitful results.

Calculation and demonstration of dynamic behavior of time dependent electromagnetic field distribution in H-plane rectangular waveguide circuit

The time dependent electromagnetic field distribution in rectangular waveguide circuits are calculated exactly, based on mode corresponding equivalent networks and excitation conditions. The dynamic behavior of fields in waveguide circuits is demonstrated by displaying the calculated field distribution in a time sequence on the monitor of a personal computer with the help of visualization software.

Electromagnetic Field Analysis Using the Analogy between H-Plane Waveguide- and Modified NRD-Type Planar Circuit

A detailed investigation of the electromagnetic field distributions inside waveguide circuits is very useful for physical understanding, for optimization of high-frequency circuit designs, and for studies of electromagnetic coupling effects for EMC and EMI. The aim of this paper is to show how to simulate and measure the electromagnetic field distributions inside waveguide-and modified NRD-type planar circuits, making use of a kind of analogy existing between H-plane waveguide- and modified NRD-type planar circuits. A electromagnetic analysis is carried out by using the FDTD or the normal mode expansion technique and measurements are carried out by using very a small probe antenna. The measurement results are in good agreement with those of the numerical analysis using the FDTD or the normal mode expansion method. Thus, the proposed measurement system offers a valid means for establishing the behaviors of more complicated discontinuity problems.