Design Of Waveguide Bandpass Filters Research Articles

Modular Design of Waveguide Bandpass Filters With Improved Stopband and High Selectivity

A class of waveguide bandpass filters (BPFs) with parallel coupling topology is proposed by stacking rectangular cavities. Compared with transversal filters, each layer comprises more than one cavity, and these cavities are cascaded with electric or magnetic coupling. The stopband performance could be improved by properly adjusting the width-length ratio of rectangular cavity to push up the higher-order modes in the cavities, while the attractive property of transversal filter, i.e., modular design, is still valid and useful in simplifying the filter design process and producing transmission zeros (TZs) out of the passband. A fourth -, sixth -, and seventh-order BPF is successively designed, and frequency of the first spurious mode is increased from 1.12 to 1.48 times the operating frequency. Due to the parallel coupling topology, multiple TZs are generated at both sides of the passband, making the suppression more than 20 dB out of passband. Among these filters, the fourth- and sixth-order BPFs are fabricated, and the measured results demonstrate the effectiveness of the proposed method.

Back‐to‐back aperture‐ and gap‐coupled discontinuities integration for band‐pass filter design

A new class of back-to-back integrated aperture- and gap-coupled discontinuities is proposed for substrate-integrated waveguide band-pass filter design. The developed structure is shown to take advantage of both discontinuities in the design of cavity and/or planar resonators with an optimum performance including higher quality factor accompanied by transmission zero realisation, wider upper stop-band with second harmonic suppression, and a considerable size reduction. The measured unloaded quality factor has been increased by a ratio of 60% in comparison to the conventional gap-coupled structures.

Tunable waveguide bandpass filter design using a sequential design process

In this study, a symmetric waveguide bandpass filter is proposed using a systematic design process. The waveguide device is designed to control the operation frequency range by changing the metallic barrier width in the system and the finite element method is employed for numerical analysis. We used topology optimization based on the On/Off method for initial concept design with the design objective to maximize the transmitted electric intensity at the target frequency. Detail two-dimensional metallic structure for a tunable bandpass filter was determined through successive parametric studies using the shape primitively derived from the On/Off method. The performance of the proposed waveguide system was verified by numerical simulations and experimental measurements.

Compact waveguide bandpass f ilter employing two-dimensional metallic photonic crystals for millimeter to terahertz frequencies

Two-dimensional metallic photonic crystal slabs with square lattice are proposed to be used for the design of waveguide bandpass filters operating in millimeter to terahertz region. Filter characteristics are studied when rod radii and lattice constants are changed. Based on the frequency scaling technique, a series of higher frequency filters has been designed. By using laser drilling and welding processing techniques, a compact waveguide filter embedded in an EIA-WR10 waveguide with central frequency 145.5 GHz and 3-dB bandwidth of 5.26 GHz is fabricated and measured. The measurement data agree well with the simulation prediction.

대역 통과 도파관 여파기 설계를 위한 이중 공진 아이리스 해석

This paper deals with transmission characteristics of a new dual resonant structure for designing waveguide band-pass filter. The structure which has a pass-band between two adjacent stop-bands in a single body consists of circular ridged aperture and four armed conducting patch. The dual resonant behavior of the structure can be represented by a combination of LC series and parallel resonant circuits. Also these resonant properties can be easily controlled by varying the geometry of the aperture and four armed conducting patch. Actually, the structure is fabricated on the microstrip substrate by use of etching technique so that it is formed an iris type resonator which can be easily put into the transverse plane of the waveguide. We use WR-90 standard waveguide, adapters, and VNA(vector network analyzer) to measure the resonant characteristics of the structure. It is very useful to design and to improve the cutoff skirts characteristics in the waveguide band-pass filter design area.

Design of waveguide bandpass filter based on nonresonating ‘T’ junctions

A design method for waveguide bandpass filters based on nonresonating ‘T’ junctions is presented. The wideband characteristics of the nonresonating waveguide ‘T’ junction are fully considered in the design method. As a design example, a four-pole waveguide bandpass filter with about 6% fractional bandwidth has been designed and fabricated. The measured results agree well with the calculated results and it shows good in-band equal ripple performance and sharp rejection performance.

Novel SIS resonators waveguide filters

A novel stepped-impedance slot (SIS) resonator waveguide band-pass filter with quarter-wave couplings is investigated. SIS resonators have been studied in order to increase the stopband width between the fundamental and spurious harmonic resonant frequencies. They have been employed in the design of waveguide band-pass filters with good harmonic suppression.

Design of 40 GHz-Band Iris-Type Waveguide Bandpass Filter

In this paper, a design method of an iris-coupled waveguide bandpass filter having 0.1 dB passband ripple and 3.5% ripple bandwidth at the center frequency of 41 GHz is described. Mode matching method is used to analyze H-plane discontinuity of waveguide and an equivalent circuit of the thick inductive obstacle is obtained from the results of the analysis. Simulation and experimental results show the validity of waveguide bandpass filter design method using mode matching method.

Edge-coupled coplanar waveguide bandpass filter design

This paper describes a new technique for the design of edge-coupled coplanar waveguide (CPW) bandpass filters at microwave and millimeter-wave frequencies. The topology consists of coupled-slot pairs that are symmetric about the center of the CPW line. By applying duality and symmetry, a design methodology is developed that follows the well-known coupled-strip approach. In order to provide filter design guidelines, a spectral domain integral equation analysis was used to characterize coupled slots on silicon with a range of geometrical parameters, through which a series of design curves were generated. Experimental results are given for 10-GHz filters printed on high-resistivity silicon, with bandwidths from 5% to 20%. It is shown how the manner of connecting filter sections can influence the frequency response.

Generalized admittance matrix analysis of cylindrical cavities coupled by rectangular apertures

The generalized admittance matrix (GAM) approach to the analysis of cylindrical cavities coupled to external waveguides by rectangular apertures is discussed. Green's dyad of the admittance type under the longitudinal section electric (LSE) field approximation is derived and GAM is obtained by Galerkin's method. Several numerical results are presented and a criterion for the optimal mode selection is discussed. A reduced formulation having improved efficiency is derived and its use is critically discussed. Comparisons with results of mode-matching, finite-element method and with measurements are shown. The analysis is successfully applied to waveguide bandpass filter design.