An HTS Wideband Filter Using Interdigital-Like Resonators at UHF Band

A wideband superconducting interdigital-like filter at UHF band has been successfully designed and fabricated. An interdigital-like resonator is proposed to realize both strong coupling and compact size. A ten-pole demonstration high temperature superconducting filter is developed with a center frequency of approximately 340 MHz and a fractional bandwidth of 26%. The measurements show that the insertion loss of the filter is less than 0.2 dB, the return loss is better than 17 dB, and the out-of-band rejection is better than 70 dB.      

Compact Wideband Bandpass Filters Using Stepped-Impedance Resonators and Interdigital Coupling Structures

This letter proposes a microstrip $lambda/4$ interdigital stepped-impedance resonator whose impedance ratio can be very low and coupling strength between adjacent resonators can be very large. On the basis of the proposed structure, one four-pole Chebyshev and one four-pole generalized Chebyshev filter with 0.05 dB equal-ripple bandwidths of 48% and 46%, respectively, are designed and fabricated. Both implemented filters have a compact size, a wide passband, a wide upper stopband, and a high spurious passband at near 5.1 times the center frequency. Good agreement between measurements and simulations is observed.      

A Rectangular-Waveguide Filter Using Trapped-Mode Resonators

A two-resonator, narrow-band waveguide filter with a very wide stop band is described. Each resonator cavity has one side wall which is entirely open except for a bifurcating E-plane septum. Energy in most modes tends to radiate freely out of the open end of each resonator to absorbing material; however, energy in the fundamental TE/sub 101/-mode is trapped in the resonator structures to give high-Q resonances such as are typical of conventional solid-wall resonators. Thus, a primary pass band is obtained similar to that of filters using conventional cavity resonators, but the many higher-order pass bands usually found in cavity-resonator filters are largely eliminated because the higher-order-mode cavity resonances are damped out. This type of filter attenuates unwanted signals mainly by reflection. For applications where a low-input VSWR is desired in the pass band, a bifurcated section of guide backed by absorbing material is also used in the input waveguide so as to tend to absorb the input energy at frequencies above that of the pass band.     

Dual-Band Microstrip Bandpass Filter Using Stepped-Impedance Resonators With New Coupling Schemes

A microstrip bandpass filter using stepped-impedance resonators is designed in low-temperature co-fired ceramic technology for dual-band applications at 2.4 and 5.2 GHz. New coupling schemes are proposed to replace the normal counterparts. It is found that the new coupling scheme for the interstages can enhance the layout compactness of the bandpass filter; while the new coupling scheme at the input and output can improve the performance of the bandpass filter. To validate the design and analysis, a prototype of the bandpass filter was fabricated and measured. It is shown that the measured and simulated performances are in good agreement. The prototype of the bandpass filter achieved insertion loss of 1.25 and 1.87 dB,$ S_11$of$-$29 and$-$40 dB, and bandwidth of 21% and 12.7% at 2.4 and 5.2 GHz, respectively. The bandpass filter is further studied for a single-package solution of dual-band radio transceivers. The bandpass filter is, therefore, integrated into a ceramic ball grid array package. The integration is analyzed with an emphasis on the connection of the bandpass filter to the antenna and to the transceiver die.     

Ultra Wideband Bandpass Filter Using Embedded Stepped Impedance Resonators on Multilayer Liquid Crystal Polymer Substrate

This letter proposes an ultra wideband (UWB) bandpass filter (BPF) based on embedded stepped impedance resonators (SIRs). In this study, broad side coupled patches and high impedance microstrip lines are adopted as quasi-lumped elements for realizing the coupling between adjacent SIRs, which are used to suppress stopband harmonic response. An eight-pole UWB BPF is developed from lump-element bandpass prototype and verified by full-wave simulation. The proposed filter is fabricated using multilayer liquid crystal polymer (LCP) process and measured using vector network analyzer. Good agreement between simulated and measured response is observed. The measurement results show that the fabricated filter has a low insertion loss of 0.18 dB at center frequency 6.05 GHz, an ultra wide fractional bandwidth of 127.3% and excellent stopband rejection level higher than 32.01 dB from 10.9 to 18.0 GHz.      

应用于多模WLANs的紧凑SIR双频带通滤波器

提出了一种基于阶梯阻抗谐振器的紧凑、高选择性的微带双频带通滤波器,使用了两个发卡型阶梯阻抗谐振器交叉组成了伪交指结构谐振器,实现了小型化双频滤波器。采用0°馈电结构引入了三个传输零点,从而提高了频率选择特性。加工了微带双频带通滤波器实物,实测结果显示,两个通带中心频率分别为2.41GHz和5.26GHz,中心频率比大于2,带内插损分别为1.06dB和1.59dB,3dB相对带宽分别为22.8%、15.6%,仿真与实测吻合较好。与传统的分支加载、阶梯阻抗等双频滤波器相比,该滤波器具有设计简单、结构紧凑、低插入损耗及高频率选择特性等优点。     

Dual-Wideband Bandpass Filter Using Short-Circuited Stepped-Impedance Resonators

A compact dual-wideband bandpass filter featuring two controllable passbands is presented and experimentally validated. The proposed filter uses shorted stepped-impedance resonators to achieve dual-wideband bandpass capability and to minimum size. Design curves are given for the filter design. It is found that the frequency ratio of the second to first band has a wide achievable range. An experimental circuit is fabricated and evaluated to validate the design concept. The measurement results correlated well with the simulation results.      

SIR实现的新型毫米波UWB滤波器

提出了一个用阶跃阻抗谐振器(SIR)实现的毫米波超宽带(UWB)滤波器。滤波器的基本单元是一个由半波长微带线谐振器和SIR组成的三模谐振器。该谐振器采用SIR结构,从而达到阻带宽、结构紧凑,且能很好地改善带外抑制。为了进一步改善阻带特性,该三模谐振器与半波长谐振器平行耦合形成新型的滤波器。该滤波器有多个传输极点和传输零点,形成陡峭的通带边缘特性和很宽的阻带。实验测得滤波器的-3 dB相对带宽为35.7%,通带内的插入损耗约为-1.7 dB。插入损耗低于-17 dB的高频端阻带可到76 GHz。滤波器的仿真结果和测试结果基本吻合。     

A Novel Wideband Bandpass Filter Using A Cross-Shaped Multiple-Mode Resonator

A novel wideband bandpass filter (BPF) using a cross-shaped microstrip multiple-mode resonator (MMR) is presented in the letter. The MMR is composed of a section of open-ended microstrip-line and a pair of short-ended stubs. Its three resonant modes are used to construct the passband of the proposed BPF. And two coplanar waveguides are used as the input/output transmission-lines to improve the coupling between the MMR and input/output transmission-lines. The filter has been investigated numerically and experimentally. Both simulated and measured results show that the filter has a good performance, including controllable bandwidth from 66% to 114%, low insertion loss (lower than 0.78 dB), and a small group delay variation.     

A Compact Dual-Band Bandpass Filter Using Meandering Stepped Impedance Resonators

This letter presents a miniaturized dual-band narrow bandpass filter (BPF) using meandering stepped impedance resonators (SIRs) with a new coupling scheme, which exhibited a size reduction of 50% compared with the traditional direct coupling structure at the same frequency, while the new structure can generate three transmission zeros in the insertion loss response. To validate the design and analysis, two dual-band BPFs centered at 2.4-GHz/5.2-GHz and 2.4-GHz/5.7-GHz for WLAN application were fabricated and measured. It is shown that the measured and simulated performances are in good agreement. The BPFs achieved insertion loss of less than 2 dB and return loss of greater than 16-dB in each band.     

A Frequency-Stabilized Microwave Band-Rejection Filter Using High Dielectric Constant Resonators

The high permittivity dielectric resonator is a low loss microwave filter element whose size is substantiality less than metal waveguide cavities. Temperature stabilizing their resonant frequency increases the applicability of such elements. A temperature compensated 3-section band-rejection filter using dielectric resonators has been fabricated and tested. The measured electrical performance was comparable to metal waveguide filters and the frequency stability for temperature variations was comparable to brass waveguide cavity filters which are not temperature compensated.     

A Compact Wideband Microstrip Filter Using Folded Multiple-Mode Resonator

A compact wideband microstrip filter using a folded multiple-mode resonator is proposed. The filter contains only one resonator, which operates as not only a resonant element but also an open stub. The filter simultaneously realizes a broad passband, a compact size, and two transmission zeros at both the lower and upper stopbands. The transmission zero mechanism is investigated in detail through the simple transmission line equation. A lucid equivalent circuit is given both for analysis and initial design of the proposed filter. The fabricated filter shows the merits which are listed as follows: compact size and sharp skirts.      

A Reconfigurable Channel Filter for Software Defined Radio Using RNS

This paper presents a high-speed FIR channel filter using residue number system (RNS) whose frequency response can be reconfigured to adapt to a multitude of channel filtering specifications of a multi-standard software defined radio (SDR) receiver. The channel filters in the channelizer of an SDR extract multiple narrowband channels corresponding to different communication standards from the wideband input signal. The proposed architecture has been synthesized on TSMC 0.18 μm CMOS standard cell technology. Synthesis result shows that the proposed reconfigurable FIR channel filter, for a Digital Advanced Mobile Phone Systems (D-AMPS) example, offers speed improvement of 42% and AT complexity reduction of 26% over existing reconfigurable FIR method.     

Stopband-Extended Balanced Bandpass Filter Using Coupled Stepped-Impedance Resonators

A novel fourth-order balanced bandpass filter is proposed based on the half-wavelength (lambda/2) stepped-impedance resonators (SIRs). By properly adjusting the parameters of each SIR, the proposed filter may be made compact and its stopband may also be extended simultaneously. Specifically, a balanced filter with acceptable common-mode rejection is implemented with its differential-mode and common-mode stopbands extended up to 5.5 f_o ^d, where f_o ^d is the center frequency of differential-mode passband.     

Wideband Parallel-Strip Bandpass Filter Using Phase Inverter

A new wideband parallel-strip bandpass filter using phase inverter with stubs is proposed. With the wideband phase inverter in the parallel-strip line structure, the measured fractional passband bandwidth is 123% with a flat group delay response. Also, over 90% impedance bandwidth is obtained for the return loss higher than 20 dB. The theoretical simulation, electromagnetic simulation, and measured results show good agreement with this proposed design.      

A Bandpass Filter Design Using Half-Wavelength Stepped Impedance Resonators With Internal Couplings

We propose a new type of microstrip half-wavelength$(lambda/hbox2)$stepped impedance resonator (SIR) for use in bandpass filter (BPF) designs. This$lambda/hbox2$SIR has an internal coupling section that can be used to generate a coupling coefficient in the filter design in addition to couplings between SIRs. It also contains additional stepped impedance lines that shift and suppress the lowest even-mode resonance frequencies to more than what can be achieved by conventional$lambda/hbox2$SIRs. Moreover, a transmission zero is generated close to its fundamental resonance frequency$(f_0)$which can be used in definition of the filter response. A fourth-order microstrip BPF with 10% bandwidth was constructed using two of the proposed$lambda/hbox2$SIRs with a stepped impedance ratio$(R)$of 0.528. The experimental result shows that the filter can achieve low in-band loss and out-of-band attenuation of 52.6dB up to$hbox3f_0$. The lowest spurious resonance frequency is shifted to$hbox3f_0$as opposed to 2.5$f_0$in conventional$lambda/hbox2$SIRs with the same$R$value.     

单层平面基片集成波导双通带滤波器的仿真研究

提出了一种基于单层基片集成波导谐振腔的双通带滤波器。滤波器由传统折叠排列的6个谐振腔组成。通过在通带内设置一对传输零点,将传统滤波器的通带一分为二,实现了双通带。仿真结果表明滤波器的两个通带分别工作于9.85 GHz和10.08 GHz,在相对带宽分别为1.29%和1.76%的通带内,插入损耗小于1.68 dB和1.3 dB,回波损耗大于24 dB和14 dB,通带之间的隔离大于17 dB。该滤波器在无线通讯系统中具有良好的应用前景。     

Novel Balanced Dual-Band Bandpass Filter Using Coupled Stepped-Impedance Resonators

A novel balanced dual-band bandpass filter, using coupled stepped-impedance resonators (SIRs), is proposed in this letter. The differential- and common-mode equivalent half circuits are given. By properly designing the resonators, associated with the filter composed of eight SIRs, dual-band differential-mode bandpass response can be obtained. To improve the common-mode suppression level, two open stubs with different lengths are added to the connection point of two resonators. A prototype balanced filter operating at 2.4 and 5 GHz has been realized to validate the proposed concept and theory.      

Bandstop Filter in Nonradiative Dielectric Waveguide Using Rectangular Resonators

A bandstop filter realized by means of rectangular resonators coupled to the center dielectric strip of a nonradiative dielectric (NRD) waveguide is described.This filter has the advantage that it is simple to manufacture, making use of a center dielectric of standard cross section. The design procedure is similar to the conventional strip line design procedure, with the stubs replaced by "stubs" of dielectric, or resonators. The design equations for the stub coupling are derived the properties of the stubs are obtained through measurement.