Wide Stopband Characteristics Research Articles

Design of coplanar-waveguide-based elliptic filter using T-shaped defected ground structure

In this paper T-shaped Defected Ground Structure (DGS) has been proposed in the ground plane of the conventional coplanar-waveguide (CPW) structure. The T-shaped DGS has wider gap capacitance than the conventional dumbbell-shaped DGS, and provides a wide stop band and slow-wave characteristics. Thus, utilizing the above properties array of two T-shaped DGS structures has been introduced to obtain an elliptic low-pass filter (LPF). This proposed LPF is suitable for transferring low frequency signal up to 2.5 GHz satisfactorily. It provides sharp transition between pass- and stop-band with good sharpness factor, but almost 1.2 dB insertion loss in the pass-band. Therefore, the insertion loss in the pass-band is reduced with the help of compensated Hi–Lo coplanar waveguide (CPW) transmission line.

Design of a compact and sharp-rejection low-pass filter with a wide stopband

In this paper, a compact and sharp-rejection low-pass filter is proposed and analyzed. By combining a stepped-impedance shunt open stub and two additional shunt open stubs, a compact low-pass filter with wide upper stopband and very high passband selectivity is realized. Wide stopband and sharp rejection characteristics are achieved by realizing three transmission zeros near the passband edges. This filter demonstrated very good measured characteristics at cut-off frequency ( of 2.49 GHz, including a low insertion loss of dB, a wide stopband from 2.8 to 7 GHz and an attenuation slope of 49 dB/GHz. Experimental results also show a good agreement with the predicted results.

Design Of Compact, Wide Stopband Bandpass Filter Using Stepped Impedance Resonator

A compact bandpass filter (BPF) with wide stopband characteristics using stepped impedance resonator (SIR) is presented. To improve stopband performance, a miniaturized short-circuit centered stepped impedance hairpin resonator (SCSIHR) with internal parallel coupled lines is proposed. Owing to the canceling effect of the mixed couplings, multiple transmission zeros can be obtained in the stopband. The odd- and even-mode analysis is applied to the proposed SCSIHR and the filter. A new BPF centered at 2.17GHz has been designed and fabricated to verify the validity of the proposed method. The measurement result shows four finite transmission zeros in the stopband, locating at 1.63 GHz, 3.99 GHz, 6.09 GHz, 14.15 GHz, respectively. The spurious frequencies are suppressed in a wide range from DC to 1.86GHz and 2.8GHz to 16.5GHz with suppression better than 20 dB. And the circuit only occupies 6.70 × 8.35mm2.

Compact dual‐plane resonant cell low‐pass filter with wide stopband characteristics

AbstractA compact microstrip dual‐plane resonant cell structure is presented. Good lowpass performance and wide stopband characteristics can be obtained with a simple single resonant cell; multiple resonant modes are introduced in the stopband, thus rejection width is significantly improved. Measured results of the fabricated prototype show that the stopband bandwidth better than −20 dB is more than 13 GHz, but its occupied area is only 20 × 30 mm2. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1776–1778, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25357

Design of a compact, wide stopband microstrip band‐pass filter

AbstractWe proposed a compact microstrip band‐pass filter with wide stopband in this article.Microstrip gap and interdigital capacitor combine with stub inductors shorted to the ground plane by via were used to take advantage of different aspects of left‐handed behavior to achieve compact size and wide stopband characteristics. The designed filter has a compact structure with overall dimensions of 20 mm by 17.05 mm, a 3‐dB bandwidth of 25.2% at 1.19 GHz, insertion loss of −3 dB, attenuation greater that 60 dB in the lower stopband and greater that 27 dB up to 5.2 times the centre frequency. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:830–833, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25061

A compact U‐shaped defected ground structure microstrip low‐pass filter with wideband rejection

AbstractA compact triple U‐shaped slots etched on the microstrip ground are used to implement a novel low‐pass filter.A rectangular open stub and a radius stub are used to produce transmission zeros and thus result in wide stopband. Good low‐pass performance and wide stopband characteristics can be achieved by this new structure. One prototype is fabricated to demonstrate the validity of the design strategies. The simulated and measured results indicate that the insertion loss is less than 0.25 dB and the return loss is less than −16.7 dB in the whole passband. In addition, significant improvement on rejection band can be observed; the stopband bandwidth better than −25 dB is about 105% (from 2.6 to 8.4 GHz). © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 497–499, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24960

Compact and wide stopband lowpass filter with novel comb CMRC

A novel comb compact microstrip resonant cell, entitled CCMRC, is firstly proposed. The compact configuration presents ultra wide stopband and attractive slow-wave characteristics. A lowpass filter, consisting of three CCMRCs connected in series, is designed and fabricated. The filter has the merits of low insertion loss in the passband, sharp, deep and wide rejection in the stopband and compact size. Good agreement between experimental and simulated results is achieved.

Improved compact microstrip resonance cell lowpass filter with wide stopband characteristics

An improved compact microstrip resonance cell (CMRC) structure is presented. Good lowpass performance and wide stopband characteristics can be achieved with a simple single resonant cell; four transmission zeros are introduced into the stopband and thus out-of-band rejection is significantly improved. Measured results of the fabricated prototype show that the insertion loss is less than 0.1 dB in the whole passband, and stopband bandwidth better than -10 dB is obtained from 2.9 to 15.9 GHz, which is an improvement of 138.3% from a conventional CMRC

Microwave Bandstop Filters Using Novel Artificial Periodic Substrate Electromagnetic Band Gap Structures

Novel microwave and millimeterwave (mm-wave) bandstop filters using artificial periodic substrate electromagnetic bandgap (EBG) are investigated in this paper. Three types of microstrip structures using periodically modified trace width, patterned dielectric substrate, and periodically modified ground plane are treated, respectively. By periodically modifying either the width of the conductor trace, the substrate height, or the dielectric constant of a standard microstrip transmission line, it has been possible to design microwave bandstop filter functions with wide stopband characteristics and reduced size, compared to conventional microwave/RF filter structures. Commercial electronic design automation (EDA) and computational electromagnetic tools such as Agilent's advanced design system (ADS) and CST Microwave Studio are used in the design and simulations of these filter structures. The effects of the physical parameters of the structures on the filter characteristic are studied. The design procedure and simulation results are described and possible applications of these filter structures are discussed in this paper. A particularly wide stopband is achieved by the circuits presented in this paper, which use only a few cell elements. A significant performance improvement of microstrip patch antenna has been observed by implementing one of the presented EBG periodic substrate structures.

Improved spiral compact microstrip resonance cell low‐pass filter with wide stopband characteristics

AbstractAn improved spiral compact microstrip resonance cell (SCMRC) structure is proposed in this article. Good low pass performance and wide stopband characteristics can be achieved with a simple single cell, two transmission zeros are introduced within the stopband and thus improve the bandwidth significantly. The measured results of the prototype show that the insertion loss is less than 0.55 dB in the passband, and the bandwidth of the stopband is about 90%, nearly two times of the original SCMRC structure. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 121–124, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22032

마이크로스트립 선로를 이용한 광대역 차단특성을 가지는 저역통과 필터 설계

본 논문에서는 광 대역 저지대역특성을 가지는 저역통과필터를 마이크로스트립 선로를 이용하여 설계 및 제작하였다. 개방회로 스터브를 이용한 L-C ladder형 저역통과 필터의 입 출력단에 길이가 <TEX>$\lambda_g/4$</TEX>인 개방 스터브를 부가함으로써, 광대역 차단특성을 가지는 필터를 개발하였다. 필터의 전체길이를 줄이기 위해 고 임피던스 마이크로스트럼 라인을 미앤더(meander) 구조로 제작하였다. 제작된 필터는 차단주파수가 2.3 GHz인 저역통과필터였고, 측정된 결과는 전산모의실험에서 예측된 값들과 잘 일치함을 알 수 있었다. In this paper, we designed and fabricated the lowpass filter with the wide stopband characteristics using microp- strip line. Adding the <TEX>$\lambda_g/4$</TEX> open stub at the input and output ports, we developed the L-C ladder type lowpass filter using the open stub which has wide stopband characteristics. In order to reduce the entire size qf this filter, the high impedance microstrip lines were made with the meander structure. The lowpass filter was fabricated with the cutoff frequency 2.3 GHz and its measured frequency responses agree well with the simulation results.

Wideband and compact bandstop filter structure using double-plane superposition

A novel bandstop filter (BSF) structure is proposed and measured for wideband and compact circuit applications. The proposed BSF realizes the wide stopband (2-octave) characteristics by superposing two different photonic bandgap (PBG) structures into a coupled double-plane configuration. Only three cells of the proposed structure are enough for the measured 10 dB stopband from 4.3 to 16.2 GHz. We expect this novel BSF structure is widely used for compact and wideband circuit applications, such as compact high-efficiency power amplitiers using harmonic tuning techniques.

A new class of miniature quadrature couplers for MIC and MMIC applications

AbstractA new class of miniature quadrature couplers suitable for microwave integrated circuits (MICs) and monolithic microwave integrated circuits (MMICs) are presented. The proposed couplers have some advantages compared to conventional types, such as smaller size, no harmonic response, and wide stop‐band characteristics. Two 3‐dB quadrature couplers at two different frequencies, 0.9 and 10 GHz have been designed and simulated. The coupler designed at 900 MHz has been fabricated on Duroid substrate with microstrip technology. Compared to the standard quadrature coupler more than 65% area savings, has been achieved, and the first higher‐order response appears at 5.8 GHz. The measured results show good agreement with theoretical prediction. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 215–219, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10421

A Design Method of Bandpass Filters Using Dielectric-Filled Coaxial Resonators (Short Papers)

Design formulas for capacitively coupled bandpass filters using dielectric-filled coaxial resonators are derived and experimentally verified. The most important advantage of this filter is its ability to provide wide stopband characteristics for harmonics suppression. Its features can be obtained from the configuration using both quarter-wavelength uniform impedance resonators (UIR's) and stepped impedance resonators (SIR's).