Design of Composite Right/Left-Handed Coplanar-Waveguide Bandpass and Dual-Passband Filters

The design and implementation of novel coplanar-waveguide (CPW) bandpass and dual-passband filters that consist of the composite right/left-handed short-circuited stubs are proposed. In contrast to the conventional short-circuited stub, whose input impedance repeats every half-wavelength, the composite right/left-handed CPW stub combines the phase-lead composite right/left-handed CPW and the phase-lag uniform CPW to achieve the arbitrary resonant frequencies with compact size. The equivalent bandpass and dual-passband LC resonators are established by investigating the frequency responses of the composite right/left-handed CPW stubs. The composite right/left-handed CPW bandpass filter is 62.5% more compact than the conventional quarter-wavelength shunt-stub CPW bandpass filter. The composite right/left-handed CPW dual-passband filter, which possesses the sharp rejection between the two asymmetric passbands, is also developed. The synthesis procedures of the composite right/left-handed CPW bandpass and dual-passband filters are successfully validated by measurement and full-wave simulation.     

Coplanar Waveguide Filters Based on Multibehavior Etched-Ground Stubs

In this paper, coplanar waveguide filters with etched-ground stubs that have multiple behaviors are proposed. The response of a unit cell is a bandreject with one or more transmission zeros according to the number and the lengths of the stubs. A library of transmission line models is being built for the basic cells and then used for the design of more elaborated structures. The potential of these new topologies is highlighted by providing different filtering structures with interesting features: a second-order narrow bandpass filter, and two configurations for a lowpass filter with a wide stopband. All theoretical predictions have been verified by electromagnetic simulation and measurements.      

Design of Artificial Lumped-Element Coplanar Waveguide Filters With Controllable Dual-Passband Responses

This study develops an analytical design methodology for synthesizing dual-passband filters with controllable frequency responses. The novel dual-passband filters are constructed from the artificial lumped-element coplanar waveguide stub whose behavior is equivalent to that of a parallel connection of series LC and shunt LC resonators. To improve the frequency response within two passbands, the impedance matching and the phase and impedance compensations are employed in filter design by attaching additional inductors and capacitors to dual-passband resonators. Two types of filters with significantly different bandwidth and separation of two passbands are implemented and the measured results are very consistent with the theoretical predictions, sufficiently validating the proposed design methodology and filter configuration. The proposed filters realized by artificial lumped-element resonators provide the advantages over conventional dual-passband filters in terms of compact size, spurious dc passband elimination, and deep suppression between two passbands.      

Dual-Band Mixer Using Composite Right/Left-Handed Transmission Lines

The concept of composite right left-handed transmission lines provides for one additional degree of freedom in realizing arbitrary dual-band frequency response devices. In this letter, an arbitrary dual-band operation mixer, based on the classical balanced mixer topology is proposed. The prototype demonstrates the mixer performance for a ratio of 2.5 between the two operation bands (860 MHz and 2,150 MHz). The conversion losses are better than 8.5 dB in both bands.     

A Novel 3-dB Directional Coupler With Broad Bandwidth and Compact Size Using Composite Right/Left-Handed Coplanar Waveguides

A wideband composite right/left-handed (CRLH) coplanar waveguide (CPW) coupler with 3-dB coupling value and quadrature phase difference is presented. Compared with the conventional edge-coupled CPW coupler, this symmetrical structure, consisting of a gap capacitor, a broadside-coupled capacitor, and a meandering short-circuited stub inductor, achieves wider operating bandwidth and larger coupling level. The 3-dB CRLH CPW coupler with 0.7mm spacing between coupled lines exhibits an amplitude balance of 2dB and a phase balance of 90⁰ plusmn 5⁰ from 3.2 to 7.6GHz. The coupled-line length and the port impedance of the proposed structure are approximately lambda/4 and 50Omega, respectively, which makes it more compact than the cascaded CRLH microstrip coupled-line coupler. To characterize this structure, the equivalent circuit model including the unique coupling mechanism within CRLH CPWs is established and verified by measurement. The signal with less dispersion on output ports is demonstrated based on the standard deviation of group delay time     

Design and Performance of Coplanar Waveguide Bandpass Filters

End-coupled resonator bandpass filters built in coplanar waveguide are investigated. The admittance inverter parameters of the coupling gaps between resonant sections are deduced from experiment, and bandpass filter design rules are developed. This allows easy filter synthesis from "prototype" low-pass designs. Measurements of single section resonator quality factors are used to predict filter insertion losses. Several examples of filters realized in coplanar waveguide are presented. Odd-mode coplanar waveguide filter elements that shortcircuit the even coplanar waveguide mode are investigated. Filter tuning, accomplished by adjusting the height of conducting planes above the resonant filter sections, is demonstrated.     

Linearity Improved Doherty Power Amplifier Using Composite Right/Left-Handed Transmission Lines

A Doherty power amplifier using composite right/left-handed transmission lines (CRLH-TL) is proposed for linearity improvement. The $lambda/$4 transmission line incorporating CRLH-TL is designed to suppress the second harmonic of the output of the main amplifier. The output power of the proposed power amplifier at the fundamental frequency (2.30 GHz) shows 31.0 dBm with 13 dBm input power excited. The Doherty power amplifier using CRLH-TL improves the linearity considerably compared to that without employing CRLH-TL.      

Switchable Composite Right/Left-Handed (S-CRLH) Transmission Line Using MEMS Switches

This letter presents a novel switchable composite right/left-handed (S-CRLH) metamaterial transmission line (TL) using MEMS switches. The proposed TL is based on a general CRLH TL with switchable capacitors and switchable shunt inductive stubs. The LH mode of the S-CRLH TL ranges from 7.5 GHz to 10.4 GHz. In these frequencies, the S-CRLH TL is able to switch from a negative phase response (phase lag) to a positive phase response (phase lead), or vice versa. This phase modulation can be obtained through a voltage, due to the use of MEMS switches. The size of the fabricated S-CRLH TL, including bias networks, is $4941 mu{rm m}times 2076 mu{rm m}$ and is compact thanks to the LH mode.      

Microstrip Coupled Line Composite Right/Left-Handed Unit Cell

This letter presents a new composite right/left-handed (CRLH) unit cell, which takes advantage of the microstrip coupled line even and odd modes. The new cell does not require vias, it is patterned on a single metal layer, and it has a geometrical circuit model that simplifies the design flow. A novel CRLH transmission line is also proposed. It does not have a cutoff frequency, the operating bandwidth extends from dc to 4 GHz, and it is balanced at the first and second transition frequencies between right- and left-handed bands. The theoretical expectations have been confirmed by EM simulations and measurements.      

Coplanar Waveguide Bandpass Filters With Compact Size and Wide Spurious-Free Stopband Using Electromagnetic Bandgap Resonators

This work presents a novel coplanar waveguide (CPW) bandpass filter (BPF) that uses electromagnetic bandgap (EBG) resonators to reduce the size and suppress the harmonic responses. The propagation characteristic of the EBG structure is investigated by its associated equivalent circuit model. Compared with the conventional half-wavelength resonator at 5GHz, the EBG resonator is 60.5 % more compact. Based on the EBG CPW resonators, the inductively-coupled two-pole BPF with 3.8% 3-dB bandwidth and 2-dB insertion loss at 5GHz is implemented. This structure generates a 59.6% reduction in size and suppresses a second harmonic passband when compared with a conventional filter. To eliminate the third harmonic response, the proposed EBG CPW BPF further incorporates two EBG structures into its input and output ports and has the merit of a small circuit area     

利用左右手传输线设计一种小型分支线耦合器

提出一种利用左右手传输线和互补螺线谐振器电路设计的小型分支线耦合器,工作频率为720 MHz.将互补螺线谐振器电路替换原微带传输线,达到了缩小器件尺寸的目的.利用Ansoft HFSS进行了仿真,此种方法设计的分支线耦合器尺寸比传统的电路缩小50%,在中心频率处耦合度(S21,S31)为-3.2 dB,隔离度(S41)...     

Quarter-Wavelength Coupled Variable Bandstop and Bandpass Filters Using Varactor Modes

A quarter-wavelength coupled bandstop filter rising varactor diodes for the 6-GHz band has been proposed and tested. Frequency giving maximum attenuation varies from 4.4 GHz-7 GHz. A quarter-wavelength coupled variable bandpass filter using varactor diodes for the 4-GHz band is also proposed and tested. The passband width varies from 730 MHz-1.22 GHz. The center frequency of the filter can also be changed.     

基于左右手传输线的小型天线设计

基于复合左右手传输线技术研究设计超小型的天线,通过对复合左右手传输线结构的适当调整获得一个零阶谐振天线,此时天线的工作频率不再依赖于天线的几何尺寸,而只与构成左手传输线的电感与电容相关,从而可大大降低天线的几何尺寸。文中基于复合左右手传输线设计了一款小型天线,使其可以工作在ISM频段,能够满足无线局域网(2.4~2.4835GHz)的要求。     

Composite Right/Left-Handed Transmission Line With Wire Bonded Interdigital Capacitor

An enhanced composite right/left-handed (CRLH) transmission line (TL) is presented in this letter. This TL, designed in microstrip technology, is implemented by means of a new improved interdigital capacitor (IDC), the so-called wire bonded IDC (WBIDC). The use of the WBIDC broadens the frequency band where the CRLH TL can be considered as a TL. A conventional 70-Omega CRLH TL (using IDCs) has been compared, by full-wave simulation and measurements, with its enhanced counterpart (using WBIDCs). In addition, this enhanced CRLH TL has been used to design a CRLH diplexer which presents several advantages over standard CRLH coupled lines (using IDCs). The diplexer response has been verified by means of a full-wave electromagnetic solver     

Dual Composite Right/Left-Handed (D-CRLH) Transmission Line Metamaterial

The novel concept of dual composite right/left-handed (D-CRLH) transmission line metamaterial is introduced. The D-CRLH is the "dual" of the conventional CRLH in the sense that it has a series parallel (instead of series) LC tank and a shunt series (instead of parallel) LC tank. This topological duality results in dual properties. The D-CRLH indeed exhibits its left-handed (LH) band at high frequencies and its right-handed (RH) band at low frequencies and is of stop-band nature, in opposition to the CRLH which is low-frequency-LH/high-frequency-RH and pass-band. The so-called balanced condition is still valid in the D-CRLH for broadband matching. However, phase origin is at dc and infinity instead, as at the LH-RH transition, and the gap between the RH and LH bands cannot be closed up in practical implementations. In contrast, the D-CRLH provides an unlimited LH bandwidth. This letter presents the homogeneous and LC-network transmission parameters and the fundamental dispersion/impedance properties of the D-CRLH     

基于复合左右手传输线的超宽带滤波器设计

本文基于复合左右手传输线理论提出了一种设计超宽带滤波器的新方法。该方法从传输的幅度和相位出发,利用微带线结构构建复合左右手传输线,通过控制复合传输线的左手响应频率和右手响应频率来构建微波带通结构。通过在微带线上采用缺陷地板结构物理上实现负等效介电常数,得到低通特性;采用微带线加载交指电容实现负等效磁导率,得到高通特性。最终通过将两种情况组合,构建具有较强左手特性和较弱右手特性的复合传输线,完成基于微带线结构的超宽带滤波器设计。文中给出的仿真结果和实测结果吻合良好,有利的证明了该方法的有效性和实用性。     

Wide-Stopband Microstrip Bandpass Filters Using Quarter-Wavelength Stepped-Impedance Resonators and Bandstop Embedded Resonators

Novel compact microstrip bandpass filters (BPFs) with extended stopband are proposed using both quarter-wavelength (lambda/4) stepped-impedance resonators and bandstop embedded resonators. First, by properly designing the impedance and length ratios of the stepped-impedance resonators, the developed filter may be made compact and its spurious harmonics may be pushed to the higher frequency region. Next, by suitably designing the bandstop structure so as to suppress the lower spurious harmonics of stepped-impedance resonators and then embedding the bandstop structure into the lambda/4 resonators, one may realize the BPFs with wideband spurious suppression. In particular, by connecting the bandstop embedded resonators to the input/output ports, a compact fourth-order BPF of dimension 0.089 lambdag times 0.27 lambdag is implemented and its stopband is extended up to 8.25 f ₀ with an adequate rejection of greater than 32.49 dB, where f ₀ is the passband center frequency and lambdag is the microstrip guided wavelength at f ₀.     

多通带复合左右手传输线的设计与仿真

提出一种具有两组复合左右手通带的平面传输线结构.与传统左手微带线相比,本结构利用连有金属折线的矩形贴片和接地板上T形DGS(defected ground structures)结构形成一组新的左手通带和右手通带.为了使左右手通带间禁带闭合,用梯形贴片及接地板上交趾DGS结构代替上述结构,最终实现具有两个零级谐振频率点的平面传输线.结构的仿真结果与利用等效电路和Bloch-Floquet原理得到的理论结果及测量结构都符合较好.这种新颖的具有多通带的复合左右手传输线可应用于多通带微波器件设计.     

Lumped-Element Quadrature Power Splitters Using Mixed Right/Left-Handed Transmission Lines

This paper presents the design of lumped quadrature power splitters (LQPSs) based on unit cells of right-handed (RH) and left-handed (LH) synthetic transmission lines (TLs). The LQPSs include a lumped Wilkinson splitter, with phase-adjusting RH/LH TLs at the outputs. Two topologies, considered to be advantageous with regards to size and electric characteristics, are studied in detail. For these two, closed-form design equations are derived and the performances are analyzed by circuit simulations. The theory and simulation results are experimentally validated by monolithic-microwave integrated-circuit prototypes designed for a center frequency of 2.5 GHz. Both prototypes have performance that agree well with theory and design simulations. Within the frequency range of 2–3 GHz, the maximum amplitude and phase errors are less than 0.3 dB and 3$^circ$, respectively. All reflections and the isolation are better than$-$10 dB. The effective areas of the two prototypes are 900$, times,$700$mu$m$^2$and 720$, times,$520$mu$m$^2$, respectively.     

Ultra-Wideband Bandpass Filters Using Quarter-Wave Short-Circuited Shunt Stubs and Quarter-Wave Series Transformers

This letter introduces a topology of a very wideband filter intended for the use in ultra-wideband 3.1-10.6 GHz applications. Basic filter configuration consists of quarter-wave short-circuited stubs and quarter-wave series transformers. To improve the out-of-band rejection, a low-pass filter is added across the symmetry plane. The proposed component is fabricated in a planar microstrip configuration; however, the topology can be easily adopted for other technologies including those based on surface micromachining. The measurements have shown an insertion loss below 0.86 dB, return loss above 14 dB, group-delay variation under 0.15 ns, and the third harmonic rejection better than 16 dB.