新型微扰结构双模贴片带通滤波器设计

针对微带滤波器高性能小型化的需求,提出了一种方环形微扰单元的双模贴片带通滤波器的设计.该滤波器由方形贴片作为谐振器,输入、输出端口采用直接馈电,具有对称结构.利用在方形贴片上蚀刻出方环形缺口的方式,对方形贴片谐振器进行微扰,实现双模滤波器.通过电磁仿真软件Ansoft HFSS分析了微扰单元的特性,对双模滤波器的性能进...     

Fractal Dual-Mode Open-Loop Quasi-Elliptic Bandpass Filter with Source-Load Coupling

To realize the feature of small size and high selectivity, a microstrip miniature fractal quasi-elliptic bandpass filter (BPF) with two transmission zeros (TZs) near each skirt is investigated in this paper. The TZs are created by source-load coupling between the input and output E-shaped feeding structures. By using a dual-mode Minkowski fractal shorted stub loaded open-loop resonator, the proposed BPF achieved a size reduction of 97.5% compared with the conventional square dual-mode loop BPF. Even mode analysis is adopted to characterize the Minkowski structure. The frequency responses of the current BPF were simulated and measured with good agreement.     

Bandpass filters using dual-mode and quad-mode Mobius resonators

Compact bandpass filters are being developed using Mobius wire-loaded cavity resonators. Initial results on tuned filters indicate that excellent filter characteristics can be attained in devices that are significantly smaller than traditional wire-loaded cavity technologies. A novel quad-mode Mobius resonator is presented which occupies the same volume as a dual-mode Mobius resonator. A four-pole bandpass filter is demonstrated using a single quad-mode Mobius resonator. Precisely controlled dielectric loading of dual-mode Mobius wire resonators has been implemented to realize bandpass filters. Two-pole and four-pole bandpass filters are demonstrated using one and two dual-mode dielectric-loaded Mobius resonators, respectively     

Design and Development of Advanced Cavity-Based Dual-Mode Filters Using Low-Temperature Co-Fired Ceramic Technology for V-Band Gigabit Wireless Systems

In this paper, a novel concept of 3-D integrated -band dual-mode cavity filters, which permit the realization of a variety of quasi-elliptic responses by creating transmission zeros, has been demonstrated using multilayer low-temperature co-fired ceramic (LTCC) technology. A single-cavity resonator is designed to generate a degenerate resonance of two orthogonal modes ( and ), enabling dual-mode operation. The appearance and elimination of transmission zeros have been analyzed through the multipath coupling diagrams and lumped-element models. The quasi-elliptic dual-mode filters with the appropriate locations of the transmission zeros are then developed for receiver and transmitter channels of a -band transceiver module. Two pre-synthesized, dual-mode cavity filters are vertically stacked with two types of inter-coupling slots (1: rectangular, 2: cross) to realize the multipole filters for 60-GHz wireless local area network narrowband applications. These proposed filters are the first to be reported and have great potential to be integrated into miniaturized -band LTCC transceiver modules.     

Design of Dual- and Triple-Passband Filters Using Alternately Cascaded Multiband Resonators

A novel method for designing multiband bandpass filters has been proposed in this paper. Coupling structures with both Chebyshev and quasi-elliptic frequency responses are presented to achieve dual- and triple-band characteristics without a significant increase in circuit size. The design concept is to add some extra coupled resonator sections in a single-circuit filter to increase the degrees of freedom in extracting coupling coefficients of a multiband filter and, therefore, the filter is capable of realizing the specifications of coupling coefficients at all passbands. To verify the presented concept, four experimental examples of filters with a dual-band Chebyshev, triple-band Chebyshev, dual-band quasi-elliptic, and triple-band quasi-elliptic response have been designed and fabricated with microstrip technology. The measured results are in good agreement with the full-wave simulation results.     

A Novel Microstrip Filter Using Three-Mode Stepped Impedance Resonator (TSIR)

A novel microstrip filter using three-mode stepped impedance resonator (TSIR) is presented, with its coupling scheme given so as to accurately predict its desired performance. A T-type open stub is introduced into the design of a miniaturized TSIR. It is shown that the developed filter exhibits quasi-elliptic characteristics with sharp skirt and wide stopband. Good agreements are obtained between its measured and simulated S-parameters.      

Realization of a dual-mode bandpass filter exhibiting either a Chebyshev or an elliptic characteristic by changing perturbation's size

A dual-mode resonator with square patches attached to inner corners of a conventional microstrip loop resonator is proposed. The two types of coupling between the degenerate modes are described by changing the perturbation's size for realization of either a Chebyshev or an elliptic function filter. A novel type of dual-mode microstrip bandpass filter using degenerate modes of this type of dual-mode resonators is developed. It is shown that the perturbation's size determines the filter characteristic, whether it is Chebyshev characteristic or elliptic characteristic.     

Dual-Mode Reconfigurable Filter With Asymmetrical Transmission Zeros and Center Frequency Control

A reconfigurable bandpass filter with asymmetrical responses is demonstrated using a dual-mode microstrip resonator. The proposed topology introduces several fixed and switchable perturbations to control the center frequency and the location of the transmission zeros of the filter. The tuning mechanism consists of capacitively loading the edges of a modified square patch resonator, in order to manipulate the current distribution of the degenerate modes. This operation results in asymmetrical responses with a center frequency tuning ratio of 10% at$X$band, and angular transmission zero displacement of$Deltaomega_z=$3.5rad/s or greater in both a lower and higher side of the passband.     

Intelligence method for optimizing a microstrip filter based on folded dual-mode resonators

An efficient method for optimizing microwave filters based on dual-mode resonators has been developed. In this method, a prior knowledge of how the passband parameters depend on the resonators’ resonant frequencies and couplings is used. It is shown that the rules for the intelligence optimization of filters, previously formulated for single-mode resonators, can also be applied to dual-mode resonators. To this end, each dual-mode resonator of the filter should be put into correspondence with its proper pair of imaginary single-mode resonators whose coupled-oscillation frequencies coincide with the frequencies of the dual-mode resonator.     

Miniature high-Q double-spiral slot-line resonator filters

A new class of low insertion-loss miniaturized filters using slot-line resonators is proposed. Miniaturization is achieved by terminating the slot line with a double-spiral inductive termination at both ends. Using this miniaturized resonator, both positive and negative couplings may be realized, and therefore, both standard coupled-line and cross-coupled quasi-elliptic filters are realizable. The unloaded Q of these slot-line filters is considerably higher than that of miniaturized microstrip filters of comparable dimensions due to the inherent higher Q of the slot line. To demonstrate the validity of the design procedures and the performance characteristics, two different types of filters were fabricated and tested. One is a four-pole Chebyshev filter and the other is a quasi-elliptic filter where, in each case, the full-wave simulations show very good agreement with measurements.     

Novel planar, square-shaped, dielectric-waveguide, single-, and dual-mode filters

This paper presents a novel concept of a square-shaped dielectric-waveguide resonator, which can easily realize a dielectric-waveguide cross-coupled filter or a dielectric-waveguide dual-mode filter, using the conventional printed circuit board (PCB) process. This planar dielectric-waveguide resonator has a higher Q value than a microstrip resonator. The physical mechanisms of both single- and dual-mode filters are elucidated. Some new coupling structures are developed for undergoing the PCB process. Filter design procedures are detailed. Design curves for the coupling coefficients of internal- and external-coupling structures are determined by full-wave finite-element-method electromagnetic calculations. Measurement results are highly consistent with theory for all trial filters. This study offers an effective means of producing low-cost high-performance planar circuit filters.     

Dual-mode triangular-patch bandpass filter using spur-lines

Without any perturbations on the surface of the patch resonator or orthogonal feed lines, a new microstrip dual-mode triangular-patch bandpass filter with low insertion loss and one transmission zero is presented. The degenerate modes are realised by use of the input/output spur-lines. It has been verified by simulation and measurement.     

A novel microstrip square-loop dual-mode bandpass filter with simultaneous size reduction and spurious response suppression

In this paper, a new capacitively stepped-impedance resonator(CSIR) is proposed to develop the microstrip square-loop dual-mode bandpass filter. Using this new design, simultaneous size reduction and spurious response suppression for the dual-mode bandpass filter can be achieved. An analytical formulation of this novel resonator is given in order to elucidate the spurious frequencies relocation design. Together with this formulation, a generalized dual-mode bandpass filter model is developed so as to ease the analysis of transmission zero and insertion loss. A prototype filter is designed at 900MHz with 1.5% fractional bandwidth. Significant spurious suppressions up to 33 and 35 dB are measured at 1.8 and at 2.7 GHz, respectively. A circuitry size reduction of 54% is achieved when compared with that of the conventional structure. Moreover, the CSIR allows frequency tuning and, thus, a varactor-tuned filter is designed and a measured tunable center frequency between 1.5-1.62GHz is demonstrated. Utilizing the proposed structure, not only size reduction,as well as spurious response suppression, but also center frequency tuning can be achieved.     

Computer-Aided Filter Alignment and Diagnosis

The cavity resonant frequencies and coupling values of a wide range of bandpass filters, band-reject filters, and equalizers have been determined in situ by computer-adjusting analytic models to fit the scattering parameters measured on an automatic network analyzer. A higher order mode elliptic filter, a dual-mode quasi-elliptic filter, and a dual-mode band-reject filter are presented as examples. The general relationships between mechanical dimensions and circuit parameters are discussed. The circuit adjustment procedure is outlined, and equations for the sensitivity coefficients of several element types are tabulated.     

A reduced-size dual-mode bandpass filter with capacitively loaded open-loop arms

A novel type of dual-mode microstrip bandpass filter using degenerate modes of a dual-mode microstrip square loop resonator with capacitively loaded open-loop arms is proposed. Such a dual-mode bandpass filter with a 0.75% bandwidth at the center frequency of 1.603 GHz is designed and fabricated to demonstrate the design of reduced-size microstrip filters. It is shown that the proposed filter has a size reduction of about 59% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop and ring resonator filter.     

新型的平面双模椭圆函数带通滤波器

根据传统的方形贴片双模滤波器,提出了一种新颖的带有两个切角的平面双模带通滤波器结构.该结构使用单个贴片谐振器并且没有耦合缝隙,通带两端各有一个衰减极点,有效减小了滤波器的辐射损耗.对该滤波器结构进行改进,又提出了一种带有两个相互正交、长度不等槽线的双模椭圆函数带通滤波器结构.该滤波器在中心频率1.8GHz处,回波损耗达到31.53 dB,通带内最小插损达到0.01 dB,3 dB相对带宽为19.44%.采用Ansotf公司的En-sem ble 8.0仿真软件进行的仿真研究.仿真结果表明该结构可以更加有效地减小辐射损耗,增加带宽,且体积比传统滤波器减小了约40%,有利于小型化.     

Dual-mode helical resonators

High performance and compact size are the most important criteria in filter-based products for satellite communication systems. Succeeding the superconducting and dielectric resonators, the conventional single-mode helical resonator ranks favorably on its high unloaded-Q per volume. Improvement of the performance has been demonstrated by operating the helical resonator at a higher order (n>0) mode. In addition, these resonators can also be fabricated onto a high dielectric-constant material to further reduce the size of the filter structure. Detailed design considerations of the dual-mode wire-wound helical resonator filter, as well as implementation of the dual-mode dielectrically loaded helical resonator filter structure, are presented in this paper     

A novel dual-mode bandpass filter with wide stopband using the properties of microstrip open-loop resonator

A novel dual-mode microstrip square loop resonator is proposed using the slow-wave and dispersion features of the microstrip slow-wave open-loop resonator. It is shown that the designed and fabricated dual-mode microstrip filter has a wide stopband including the first spurious resonance frequency. Also, it has a size reduction of about 50% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop, and ring resonator filter.     

一种新颖的微带低通滤波器

提出了一种小型超宽低通微带滤波器的新型结构,即微带与共面波导紧耦合结构。该微带滤波器由接地板上一个共面波导谐振器与基片另一面上开槽的微带结构发生耦合,得到两极点,准椭圆函数响应滤波器,通带上限频率有一个传输零点。该结构有尺寸小、通带损耗小和群时延好等特性。