Open Stub Structure Research Articles

Multiwideband Bandpass Filter Based on Folded Quad Cross-Stub Stepped Impedance Resonator

A multiwideband bandpass filter (MW-BPF) using a quad cross-stub stepped impedance resonator (QC-SSIR) was simulated, fabricated, and measured. The proposed QC-SSIR is designed on a four-series arrangement of crossed open stub (COS) structures where each open stub is developed with a step impedance resonator (SIR) structure to generate a wide bandwidth. Compared to the COS resonator, the QC-SSIR has a wider fractional bandwidth and good transmission coefficients and is compact. ABCD matrix analysis is used to investigate the filter structure. Furthermore, the MW-BPF is designed on an FR4 microstrip substrate with εr = 4.4, thickness h = 1.6 mm, and tan δ = 0.0265. The results show that the proposed MW-BPF using a QC-SSIR achieves transmission coefficients/fractional bandwidths of −0.60 dB/49.3%, −1.49 dB/18.7%, and −1.93 dB/13.9% at 0.81 GHz, 1.71 GHz, and 2.58 GHz, respectively. Furthermore, to reduce the filter size, a folded QC-SSIR (FQC-SSIR) structure was also proposed. The results show that the proposed MW-BPF using an FQC-SSIR achieves transmission coefficients/fractional bandwidths of −0.57 dB/49.6%, −1.21 dB/17.7%, and −1.76 dB/12.5% at 0.82 GHz, 1.80 GHz, and 2.62 GHz, respectively. The size of the proposed MW-BPF using an FQC-SSIR is reduced by up to 46% compared with the MW-BPF using a QC-SSIR. Finally, the performance of the simulated MW-BPF based on the QC-SSIR and FQC-SSIR was in good agreement with the measurement results.

Design and Simulation of Microstrip Hairpin Bandpass Filter with Open Stub and Defected Ground Structure (DGS) at X-Band Frequency

In this paper we have designed and simulated a Band Pass Filter (BPF) at X-band frequency. This filter is designed for X-band weather radar application with 9500 MHz center frequency and bandwidth -3 dB is 120 MHz. The filter design was performed using a hairpin microstrip combined with an open stub and defected ground structure (DGS). The substrate used is Rogers RT5880 with a dielectric constant of 2.2 and a thickness of 1.575 mm. Based on the simulation results, it is found that the filter works on frequency 9,44 - 9,56 GHz with insertion loss value at pass band is -1,57 dB.

Wideband power line isolation using open stub structures

A wideband isolation topology of a power line is proposed, using open stub structures for high-speed digital interconnects. To reduce the coupled noise to the power line in the absence of a common-mode choke (CMC), which could degenerate signal integrity due to its loss and unbalanced properties, ferrite bead and open stub structures are utilised as they are suitable to the small size of commercial systems. In terms of the enhanced isolation characteristics, the induced power noise is reduced from 83 to 12 mV (86% reduction ratio) under a mobile high-definition link data transfer without data losses. Therefore, the proposed open stub structures are a very effective tool for both power integrity and signal integrity, and most importantly the cost is minimal when the CMC is removed from the high-speed digital interconnect.

Low-Voltage, Wide-Locking-Range, Millimeter-Wave Divide-by-5 Injection-Locked Frequency Dividers

A new injector topology is proposed for the design of CMOS millimeter-wave divide-by-5 injection-locked frequency dividers (ILFDs). The topology is based on a distributed-element harmonic termination by an open-stub structure connected to the floating source end of the differential injection pair. ILFDs operating at 24 and 60 GHz are demonstrated in this study. The new topology combined with an N-MOS cross-coupled oscillator core can greatly reduce the supply voltage and power consumption requirement of the divider. The simulated results indicate that, by using the distributed-element harmonic termination, the locking range can be improved by over 40 and 72% for the 24- and 60-GHz operations, respectively. The test circuits for the 24- and 60-GHz ILFDs are implemented by a 0.18-m and 90-nm CMOS process, respectively. The power consumption is 7.4 and 3.75 mW at a supply voltage of 0.7 and 0.6 V, with a very wide locking range of 1.9 and 4.1 GHz, for the 24- and 60-GHz ILFDs, respectively. The proposed 24- and 60-GHz divide-by-5 ILFDs have the outstanding figure-of-merit (FOM) values of 6.4 and 69.4, respectively, compared with reported works.

Compact Modified Pentaband Meander-Line Antenna for Mobile Handsets Applications

A printed pentaband antenna for mobile handsets application is proposed in this letter. This antenna consists of a printed nonuniform meander line with perpendicular feed and open-stub structure, making it easy to operate in code-division multiple access (CDMA, 824-894 MHz), Global System for Mobile communications (GSM, 880-960 MHz), digital communication system (DCS, 1710-1880 MHz), personal communication system (PCS, 1850-1990 MHz), and wideband code division multiple access (WCDMA, 1920-2170 MHz). The experimental results of the constructed prototype are evidenced by mitigating the degradation of antenna bandwidth due to human head and hand effect, and the measurement results of specific absorption rate (SAR) are also presented.

DGS를 이용한 Kuroda 저역통과여파기 설계

This paper presents a new open stub structure of Kuroda low-pass filter using DGS(Defected Ground Structure). The open stub having 130ohm is made with equivalent new structure using DGS. This method enable to the fabrication of Kuroda low-pass filter by extending width of the line. In case of FR4(er

COMPACT, ULTRA-BROADBAND COPLANAR-WAVEGUIDE BANDPASS FILTER WITH EXCELLENT STOPBAND REJECTION

A compact, ultra-broadband coplanar-waveguide (CPW) bandpass fllter (BPF) is demonstrated. The proposed CPW-BPF is essentially designed by exploiting CPW short-stub and open-stub structures. Technically, the proposed fllter comprises shunt short- stub and series open-stub structures that are connected in a cascade topology. The higher and lower cutofi frequencies are mainly related to the electrical length of the shunt short stub and the series open stub, respectively. In addition, the stopband rejection is enhanced through an incorporation of CPW bandstop structures. The proposed fllter design is verifled through experimental demonstration. The corresponding lumped equivalent and transmission-line equivalent circuits are provided for circuit design purpose. Compared with the classical CPW-BPFs, the proposed fllter is of a relatively simple and compact conflguration. The demonstrated CPW-BPF has about 110% 3-dB fractional bandwidth, sharp selectivity, and great stopband rejection.

Tunable sharp notch filter for UWB application

AbstractThis article presents a novel tunable sharp notch filter using open stub structure with varactor for implementing detect‐and‐avoid method into ultrawideband radio system. On the basis of the experimental results on the open stub structure with lumped capacitor, we introduced two techniques in this work to realize a tunable sharp notch filter using open stub structure with varactor to perform narrow stopband and using resistors to build a DC bias circuit, so that no influence to the tunable notch filter over a wide band. The developed tunable notch filter has excellent performance: wide tuning range from 3.65 to 4.35 GHz with low tuning voltage from 0 to 6 V, narrow bandwidth less than 270 MHz of the notch filter (at 10 dB insertion loss at 0 V), and compact size of the developed filter: about 2.0 cm × 4.0 cm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2712–2715, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23773

A Study of Planar Printed Dipole Antennas for Wireless Communication Applications

This paper presents the structure analysis, numerical design simulation, fabrication, and measurements of printed dipole-antennas for wireless communications. Two types of integrated microstrip balun, λ/4 open-stub and via-hole structures, are studied and compared. A developed finite-difference time-domain (FDTD) code and commercial Ansoft HFSS EM solver are used for design simulation and comparison. Design examples of 2.4- and 5-GHz printed dipole antennas with integrated balun are fabricated on an FR-4 printed-circuit-board (PCB) substrate. It is found that the 2. 4-GHz printed dipole with a via-hole balun has wider bandwidth (30%) than that with an open-stub balun (20% for VSWR < 2). The 5.7-GHz printed dipole with a via-hole balun has a bandwidth of approximately 20% (for VSWR < 2). The effect of the printed dipole length and arm-width on the antenna resonant central frequency and bandwidth has also been investigated. The measured antenna patterns are very close to that of an ideal dipole antenna for both 2.4- and 5.7-GHz printed dipole. Also, the design metrology of the printed dipole is applied to design a 5 GHz polarization-diversity planar antenna fabricated on a FR-4 PCB. It consists of two orthogonal 5-GHz printed dipoles with a microstrip via-hole balun feeding structure integrated with a p-i-n diode circuit to switch and select the desired antenna polarization. In the antenna design simulation, again the FDTD is employed to analyze the entire antenna structure including the lumped elements of the p-i-n diode switching circuit. Since the printed dipole structure can be used in many extended antenna structures, this study will be very useful for antenna design in wireless communication applications.

Improved tunable coplanar waveguide (CPW) bandstop filter

AbstractAn improved tunable coplanar waveguide (CPW) bandstop filter, which exhibits good performance, is proposed in this paper. A novel tunable open stub and a useful formula for frequency shift and impedances are also presented. Further, air bridges and a special method of step compensation in the angle bends are employed to overcome differences in the radiation effects as much as possible. From the measured results, a 33% narrower rejection bandwidth with sharper roll‐off was achieved, particularly in comparison to that of the bent filter. An enormous size reduction of 53% was obtained, compared to the conventional open‐stub structure. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 198–200, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20091

Novel reduced-size coplanar-waveguide bandpass filter using the new folded open stub structure

Proposes a novel folded skill and a simpler method than that of older methods. The advantages of this new structure reveals a better skirt factor than that of the conventional folded /spl lambda//4 series open stub, and it reduces the folded area of the conventional structure by at least 50%. Besides, by using the new folded /spl lambda//4 open stub to realize a bandpass filter, the size of the circuit will be reduced greatly and achieve better stopband rejection.