Elliptic-Function CPW Low-Pass Filters Implemented by Means of Open Complementary Split Ring Resonators (OCSRRs)

In this letter, an elliptic low-pass filter (LPF) implemented in coplanar waveguide (CPW) technology by etching open complementary split ring resonators (OCSRRs) in the central strip is presented for the first time. The OCSRRs behave as series connected parallel resonant tanks, whereas metallic patches etched in the back side of the substrate provide the required shunt capacitance to achieve the elliptic function response. An order-5 elliptic LPF has been designed and fabricated to illustrate the possibilities of this new approach. The measured frequency response is in good agreement with the ideal elliptic function up to twice the cutoff frequency $(f_{c}=1 {rm GHz})$. Since OCSRRs are electrically small resonators, filter dimensions are also small (device length is 2.5 cm, namely $0.13lambda$ , where $lambda$ is the guided wavelength at $f_{c}$). This work is illustrative of the possibilities of OCSRRs for the design of compact planar filters and other microwave components.      

基于互补开口环谐振器的超宽带低通滤波器

为有效抑制寄生通带和高次谐波的影响,采用互补开口环谐振器结构设计了三种紧凑的新型超宽带低通滤波器。研究了互补开口环谐振器级联的阻带特性,并用来改善滤波器的通带、阻带性能。通过对比第一种滤波器的仿真结果,表明加载互补开口环谐振器的低通滤波器具有更好的裙边衰减和更优的阻带特性。在此基础上,还设计了另外两种新型的超宽带低通滤波器,并对三种滤波器进行了加工和测量,实测结果与仿真结果均较吻合。相关结果表明,三种滤波器具有紧凑的结构、超宽的通带,并在较宽阻带内具有良好的衰减性能。     

Varactor-Loaded Complementary Split Ring Resonators (VLCSRR) and Their Application to Tunable Metamaterial Transmission Lines

In this letter, the varactor-loaded complementary split ring resonator (VLCSRR) is presented for the first time. This particle is the dual counterpart of the varactor-loaded split ring resonator (VLSRR), which was introduced previously by some of the authors. Thanks to the presence of the varactor diodes, the electrical characteristics of the particle can be electronically tuned. Thus, by loading a microstrip line with VLCSRRs, the structure exhibits a tunable rejection band which is attributed to the negative effective permittivity provided by the particle. It is also shown in this letter that by adding a gap to the structure, the rejection band is switched to a tunable pass band with left handed wave propagation. Due to the topology of the complementary split rings resonators, the insertion and polarization of the diode varactors is not straightforward. These aspects are discussed in the letter. A circuit model for the VLCSRR is proposed. From parameter extraction and comparison between simulation of the circuit model and experiment good agreement is obtained.     

基于新型互补开环谐振器的基片集成波导滤波器

设计了一种新型的互补开环谐振器(Complementary split ring resonators,CSRR),研究了新型CSRR应用在基片集成波导(Substrate integrated waveguide,SIW)时的频率响应。采用该结构设计并制作了两个SIW滤波器,其中心频率分别为5 GHz和6 GHz,带宽分别为800 MHz和2 GHz,设计和实测结果较为吻合。     

Design of Wide-Band Semi-Lumped Bandpass Filters Using Open Split Ring Resonators

Open split ring resonators (OSRRs) are used in this letter to design wide-band semi-lumped bandpass filters. OSRRs work as lumped LC series elements due to their small electrical size and can be then used as building blocks of reduced size band pass filters. The values of the capacitance, C, and inductance, L, of the OSRR are controlled by adjusting the geometrical parameters of the coupled open rings. In our design, the OSRRs are connected through quarter-wave lines which act as inverters. The impedance of these inverters have been conveniently calculated to achieve the filter specifications. Finally bending and/or meandering techniques have been applied so as to obtain highly compact designs. Experimental verification is provided and good agreement has been found between electromagnetic simulations and measurements     

基于新型互补开环谐振器的带通滤波器

展示了一种新型互补开环谐振器(Complementary Split Ring Resonators,CSRR).文章分析了CSRR的运行机理,研究了环缝的半径、径向间距对带通滤波器性能的影响,将该结构用于一个三阶波导带通滤波器的设计.并采用有限元法对这种结构的传输特性进行了仿真.仿真结果表明,所设计的波导带通滤波器带宽满足指标700 MHz,中心频率10 GHz,插损0.5 dB,具有体积小、性能高的特点.     

逆开环谐振器在微带天线谐波抑制中的应用

介绍了一种利用逆开环谐振器实现微带天线谐波抑制的方法.在传统逆开环谐振器的开口处添加一对缝隙,可有效的降低传输零点的位置.提出了加载逆开环谐振器微带线的等效电路模型,电路模型结果与仿真结果相吻合,证明了所提电路模型的正确性,并从等效电路模型的角度分析了传输零点下降的原因.将不同传输零点的结构单元级联起来制作在微带线的接地板上,很好地实现了微带天线的谐波抑制.仿真结果与测试结果相吻合,证明了所采用方法的有效性和正确性.该设计方法结构紧凑,简单易行.     

Application of Composite Right/Left Handed (CRLH) Transmission Lines based on Complementary Split Ring Resonators (CSRRs) to the Design of Dual-Band Microwave Components

In this letter, composite right/left handed transmission lines based on complementary split ring resonators are applied to the design of dual-band microwave components. Specifically, impedance inverters operative at two (arbitrary) different frequencies (one of them within the left-handed band and the other within the right-handed band) are designed and applied to the implementation of a dual-band branch line hybrid coupler. The characterization of this device reveals good performance and dual-band operation. The fabricated device is small, fully planar, and vias are not required.      

Miniaturized Microstrip Patch Antenna Array for ISM Band Using Complementary Split Ring Resonator

Wireless Personal Communications - These days patch antenna arrays are widely used in various communication systems. In this research design of miniaturized microstrip patch antenna array is...     

Miniaturized Hexagonal Stepped-Impedance Resonators and Their Applications to Filters

Miniaturized hexagonal stepped-impedance resonators and their applications to bandpass filters are presented. Based on the odd- and even-mode equivalent circuits, the resonance characteristics of these resonators are investigated. A series of circuit configurations, including the third-order Chebyshev, trisection, and fifth-order cascaded trisection filters, are constructed by the proposed resonators. These filters are very compact and have good stopband responses. Measured results validate the analysis and theoretical prediction with good agreement.     

Novel Centrally Loaded Resonators and Their Applications to Bandpass Filters

This paper presents several novel centrally loaded resonators and their applications to various types of bandpass filters. Based on the theoretical analysis, it is found that the even- mode resonance of the proposed resonators can be conveniently controlled without affecting the responses at the odd-mode resonant frequencies. Benefiting from this feature, the resonator can be utilized to design not only harmonic-suppressed bandpass filters and dual-band bandpass filters but also tunable bandpass filters. The tunable filter offers a fixed passband and a tunable one. The center frequency of the upper passband can be electrically tuned, whereas the performance of the lower one is maintained constant. To demonstrate these applications, four filters using the proposed resonators are implemented. The experiments verify the theoretical predictions and simulations.     

Substrate Integrated Waveguide Loaded by Complementary Split-Ring Resonators and Its Applications to Miniaturized Waveguide Filters

A substrate integrated waveguide with square complementary split-ring resonators (CSRRs) etched on the waveguide surface is investigated in this paper. The proposed structures allow the implementation of a forward-wave passband propagating below the characteristic cutoff frequency of the waveguide. By changing the orientations of the CSRRs, which are incorporated in the waveguide surface and can be interpreted in terms of electric dipoles, varied passband characteristics are observed. A detailed explanation for the generation and variations of the passbands has been illuminated. The application of this waveguide and CSRR combination technique to the design of miniaturized waveguide bandpass filters characterized by transmission zeros is then illustrated. Filter design methodology is examined. These proposed filters exhibit high selectivity and compact size due to the employment of the subwavelength resonators and an evanescent-wave transmission. By slightly altering the configuration of the CSRRs, we find that the propagation of the TE₁₀ mode can be suppressed and filters with improved selectivity and stopband rejection can be obtained. To verify the presented concept, three different types of filters are fabricated based on the standard printed circuit board process. The measured results are in good agreement with the simulation.     

An Investigation of Open- and Short-Ended Resonators and Their Applications to Bandpass Filters

In this paper, we investigate both open- and short-ended half-wavelength microstrip resonators and their applications to bandpass filter designs. Using voltage-wave analyses, we examine the resonance and coupling properties of these resonators at their fundamental and harmonic frequencies. Loading them with a lumped-circuit element at the locations of zero-voltage point of the second harmonic allows control of fundamental frequency response without altering that of the second harmonic. A resistive loading can suppress the second harmonic while a p-i-n diode loading yield a switchable bandpass filter. The coupling regions between an open-ended resonator and a short-ended resonator of higher order bandpass filters can be chosen such that second-, third-, and fourth-harmonic suppression, as well as dual passband, can be achieved. Simulation and experimental results agree well, validating the proposed bandpass filter design methodology.     

An Extended Doublet Substrate Integrated Waveguide (SIW) Bandpass Filter With a Complementary Split Ring Resonator (CSRR)

An “extended doublet” bandpass filter (BPF) is proposed using a substrate integrated waveguide (SIW) cavity with a complementary split ring resonator (CSRR) etched on its top metal plane. Thus, a single-layer BPF with two transmission zeros is realized successfully, with no additional area or layers occupied. The measured and simulated S-parameters of the filter are presented to show its predicted performance, with good agreements obtained between them.      

Mode Chart for Microstrip Ring Resonators (Short Papers)

A universal mode chart for the microstrip ring resonator, based on a radial waveguide model, is presented. The resonant frequency is related to the width of the ring conductor. Experimental results from 4 to 16 GHz are shown to be in good agreement with the theory.     

Compact Grating Structure for Application to Filters and Resonators in Monolithic Microwave Integrated Circuits

Possible high-Q circuits based on a new crosstie overlay slow-wave structure are proposed for monolithic microwave integrated circuits. Configurations and results of slow-wave factors are presented. This structure is used for construction of a frequency-selective reflector with a compact size. The effect of loss is considered.     

GaAs FET Current-Mode Integrators and Their Application to Filters

In this paper, current-mode integrators which consist of only n-channel depletion-mode FET and their application to filters are presented. Lossy integrator is simply realized with a capacitor and a grounded gate FET. Lossless integrator can be obtained by providing a lossy integrator with a positive feedback. To do this, multi-output current mirror is proposed. To reduce 2nd-order harmonic and THD of the filter, unbalanced/balanced conversion circuit is proposed. As an application example, 3rd-order leapfrog low-pass Chebyshev filter is simulated with GaAs MESFET process parameters. Simulation results show good performances.     

Compact Planar Dual‐Wideband Bandstop Filters with Cross Coupling and Open‐Ended Stepped Impedance Resonators

This letter presents the design of a compact bandstop filter (BSF) operating at two frequencies. The proposed BSF consists of open‐ended stepped impedance resonators (OSIR) and an end‐shorted parallel‐coupled microstrip line (E‐PCML). The OSIRs are used to achieve the impedance‐controlled stopband positions. The wide BSF bandwidths are achieved through enhanced coupling of the E‐PCML. Explicit design guidelines are derived using a lossless transmission line model. To validate theoretical predictions, a prototype dual‐band BSF operating at 900 MHz and 2,100 MHz with fractional bandwidths of 72% and 36% respectively, is implemented in microstrip.