T. Anada

Novel microstrip dual-band bandstop filter with controllable dual-stopband response

In this paper, a novel dual-band bandstop filter (DBBSF) is proposed by using composite shunt resonators, and an approximate design method is developed based on the lumped-element circuit of the filter. Both the midband frequencies and the stopband widths of the dual bands of the filter can be controlled separately. A dual-band BSF with center frequencies of 1.7 and 2.3 GHz is designed and fabricated using microstrip lines. The measured frequency response agrees excellently with theoretical predictions, validating well the proposed design theory and filter structure.

Planar Circuit Equation and its Practical Application to Planar-Type Transmission-Line Circuit

This paper presents general circuit equation of planar circuit basing on the field theory and systematic method of analysis basing on the conventional circuit theory. As an example of the application, planar-type transmission-line circuits are analyzed.

Wide angle beam propagation using oblique coordinates transformation

We propose a new wide-angle beam propagation algorithm based on an oblique coordinate transformation which extends the range of angled configurations for which beam propagation methods are accurate. This offers an extra degree of freedom within configuration and method when applying BPMs in the design of general photonic integrated circuits incorporating angled waveguide sections. The present oblique wide angle propagation technique is compared with the conventional wide angle BPM through numerical examples which are a tilted propagation in a dielectric waveguide and the diffraction of a focused Gaussian beam in a homogeneous medium.

Electric field distributions in microwave planar circuits by small coaxial probe and comparison with FDTD method

A detailed investigation of the 2D electric field distributions in bandpass filter elements that consist of microwave planar structures such as microstrip and coplanar waveguide is very useful for physical understanding, accurate and high-speed filter design and studies of electromagnetic coupling effects. By using a small electric coaxial probe, two dimensional electric field distributions for filter elements are measured. The proposed measurement system is very simple, wideband and accurate and does not required complicated system. Comparing the FDTD calculated results with measured results, the agreement is good. The upper limit of the operating frequency and the spatial resolution for the measurement system is clarified.

Synthesis of planar microwave band-pass filter based on Foster-type network and normal mode expansion method

A novel synthesis method of a planar microwave bandpass filter based on the Foster-type network and the normal mode expansion method is proposed. As an example of the synthesis, maximally flat bandpass filters were synthesized in a two-dimensional stub-type planar structure. Corresponding stripline filters were fabricated and measured. The results agree well with theory, which demonstrates the validity of the synthesis described.<<ETX>>

Microstrip bandpass filters using degenerate dual-modes of slotted equilateral triangular patch resonators

Two compact and low loss dual-mode filters are proposed by using degenerate modes of slotted triangular microstrip patch resonators. The geometrical size and radiation loss of the triangular patch are reduced simultaneously by loading transverse and longitudinal slots. The resonant frequencies of two degenerate modes can be easily controlled by varying the dimensions and positions of the slots. A two-pole dual-mode filter operating at 3.94 GHz with a fractional bandwidth of 4.3% is designed, fabricated, and measured. The measured results verify well the theoretical predictions.

Systematic analysis method of E- and H-plane circular bend of rectangular waveguide based on the planar circuit equations and equivalent network representation

A systematic analysis method to calculate the frequency characteristics of E- and H-plane circular bends of any bend angle and curvature for a rectangular waveguide is proposed. The wide band frequency characteristics of a 90/spl deg/ bend angle are calculated for a wide range of bend curvature including a sharp bend by this method.<<ETX>>

An efficient method for solving 3D dielectric planar circuit with parabolic equation

In this paper, a 3D wide-angle parabolic equation algorithm combining the Douglas scheme and the Pade series expansion is given for photonic integrated circuits and devices. The present method is easy to solve numerically by using the operator splitting method in allowing wider propagation angles, and the truncation error of the Douglas operator scheme is fourth-order O(/spl Delta/x/sup 4/) for finite differences in the transverse direction. Therefore, it is expected that this technique can improve the accuracy and efficiency of computation for optical field propagation. Finally, numerical examples are presented for a ridge-type 3D waveguide, a curved 3D waveguide model and a primitive MMI device.

Propagation properties of multilayer thin-film polarization-maintaining optical 3-D waveguide

A novel single-mode and polarization-maintaining three-dimensional optical waveguide is proposed. The structure of the optical waveguide proposed here consists of lamination of very thin-films of two optical materials with different refractive indices and the rib-type waveguide for the confinement of the optical field in the vertical and horizontal direction, respectively. The method of analysis is based on the equivalent multimode transmission line model and the transverse resonance condition. This method is used to investigate the propagation properties of the guided wave for various structure parameters. Some numerical results are presented.<<ETX>>

Design of wideband filters with high skirt-selectivity using improved parallel-coupled three-line units

An improved compound three-line unit is proposed to implement wideband bandpass filters with high skirt-selectivity and out-of-band characteristics. A corresponding two-step design/synthesis scheme is proposed to design the filter. Firstly, a filter consisting of two cascaded parallel-coupled lines with two short-circuited stubs loaded at input and output-ports is synthesized based a Chebyshev Function. Then, in order to improve the skirt characteristics, two 5/4 wavelength SIRs are inserted into between the parallelcoupled lines, whereas twp two-section open-circuited stubs are designed to replace the short-circuited ones loaded at the ports to create multiple transmission zeros. Finally, a wideband filter with a bandwidth of 3-5GHz (FBW:50%) is designed to validate the effectiveness of the proposed structure and corresponding design scheme.