Ridge Waveguide Filter Research Articles

Stripline Transition to Ridge Waveguide Bandpass Filters

Full wave optimization is implemented to design a wide band transition from shielded stripline to ridge waveguide. A bandpass ridge waveguide filter, with input/output realized through tapped-in stripline is designed. Using rigorous mode matching technique the generalized scattering matrices of all the building blocks are obtained. Design procedure is described and examples are given to demonstrate the features of the tapped-in coupling structure. The tapped-in structure results in a considerable reduction of the filter's total length compared to the use of two transitions.

Direct-coupled waveguide filters for the lower gigahertz frequency range

An analysis method based on the coupled-integral-equations technique (CIET) and the mode-matching technique (MMT) is presented for the design of a variety of direct-coupled waveguide filters suitable for applications in the lower gigahertz frequency range. The method is verified by comparison with data obtained through other numerical techniques and measurements. With reference to standard waveguide filters, the issues of filter miniaturization and stopband extension toward higher frequency bands are investigated. For given frequency specifications in the 2-GHz frequency range, examples of rectangular coaxial waveguide filters, ridge waveguide filters, ridge waveguide filters including coupling irises and T-septum waveguide filters are presented. It is demonstrated that the rectangular/square coaxial waveguide filter achieves the highest degree of miniaturization, but that ridge and, especially, T-septum waveguide filter technology is advantageous with respect to stopband performance toward higher frequencies. In particular, a T-septum filter centered at 2.155 GHz is shown to block the entire frequency range up to 7.5 GHz. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 217–225, 2002.

Low-temperature cofired ceramic (LTCC) ridge waveguide bandpass chip filters

Full-wave mode-matching-based design of generalized ridge waveguide evanescent mode bandpass filters and their transitions for low-temperature cofired ceramic (LTCC) application is described. A modification factor is introduced in the prototype filter design to effectively overcome the filter bandwidth distortion. Design examples are given to demonstrate the validity. An S-band single-ridge waveguide filter and its transitions are simulated and successfully built in LTCC packages. Good agreement between the theory and experiment is obtained, which demonstrates the feasibility of the three-dimensional ridge waveguide filter embedding in LTCC packages. As compared with an LTCC inductive windows waveguide filter realization, the ridge waveguide filter realization shows significant advantages of smaller size and comparable loss. Design consideration and LTCC realization of the low-loss ridge waveguide filter are also provided.

LTCC wide-band ridge-waveguide bandpass filters

A ridge-waveguide tap-in coupling structure is applied to the design of wide-band ridge-waveguide bandpass filters using low-temperature cofired ceramic (LTCC). The design is based on rigorous mode-matching modeling, which takes the higher order mode interactions into account. A design procedure is described and design examples are given to demonstrate the features of the proposed coupling structure. A wide-band LTCC ridge-waveguide filter is simulated and successfully built. Good experimental results are obtained.

Automated design of waveguide components using hybrid mode-matching/numerical EM building-blocks in optimization-oriented CAD frameworks-state of the art and recent advances

Fast hybrid mode-matching/boundary-contour (MM/BC) and mode-matching/finite-element (MM/FE) waveguide building blocks are described for the optimization-oriented use in powerful circuit computer-aided design (CAD) tools and the automated design of waveguide components. The efficient electromagnetic (EM) CAD technique allows the accurate design of a comprehensive class of rectangular and circular waveguide components including realistic structures of higher complexity. The efficiency and flexibility of the hybrid CAD method is demonstrated at advanced EM design examples, such as broad-band circular-to-rectangular waveguide transitions including octagonal cross sections, waveguide resonator filters with rounded corners, optimum-shaped bends, dual-mode filters with coupling sections without tuning screws, ridged waveguide filters with rounded corners, and multiplexers. The designed components are directly amenable to cost-efficient fabrication techniques like computer-controlled milling methods. The theory is verified by available measurements.