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Showing papers on "Stopband published in 2010"


Journal ArticleDOI
TL;DR: In this article, a fiber-based Fabry-Perot cavity with CO2 laser-machined mirrors was realized, which combines very small size, high finesse, small waist and mode volume, and good mode matching between the fiber and cavity modes.
Abstract: We have realized a fiber-based Fabry-Perot cavity with CO2 laser-machined mirrors. It combines very small size, high finesse F>=130000, small waist and mode volume, and good mode matching between the fiber and cavity modes. This combination of features is a major advance for cavity quantum electrodynamics (CQED), as shown in recent CQED experiments with Bose-Einstein condensates enabled by this cavity [Y. Colombe et al., Nature 450, 272 (2007)]. It should also be suitable for a wide range of other applications, including coupling to solid-state emitters, gas detection at the single-particle level, fiber-coupled single-photon sources and high-resolution optical filters with large stopband.

418 citations


Journal ArticleDOI
TL;DR: In this article, a fiber-based Fabry-Perot cavity with CO2 laser-machined mirrors was realized, which combines very small size, high finesse, small waist and mode volume, and good mode matching between the fiber and cavity modes.
Abstract: We have realized a fiber-based Fabry–Perot cavity with CO2 laser-machined mirrors. It combines very small size, high finesse , small waist and mode volume, and good mode matching between the fiber and cavity modes. This combination of features is a major advance for cavity quantum electrodynamics (CQED), as shown in recent CQED experiments with Bose–Einstein condensates enabled by this cavity (Colombe Y et al 2007 Nature 450 272). It will also be suitable for a wide range of other applications, including coupling to solid-state emitters, gas detection at the single-particle level, fiber-coupled single-photon sources and high-resolution optical filters with large stopband.

342 citations


Journal ArticleDOI
TL;DR: In this article, the authors proposed a novel wideband and miniaturized common-mode noise suppression filter based on the concept of an effective negative-permittivity metamaterial (MM) transmission line (TL).
Abstract: A novel wideband and miniaturized common-mode noise suppression filter is proposed based on the concept of an effective negative-permittivity metamaterial (MM) transmission line (TL). The propagation properties for the odd and even modes in the proposed structure are derived from the TL theory and Bloch theorem. Two- and four-port equivalent-circuit models are developed to explain the common-mode suppression characteristics. The dispersion relation has a good agreement with the full-wave simulation and measurement result. Based on the low-temperature co-fired ceramic fabrication technology, miniaturized common-mode filters with four and eight cells are realized using the concept of the effective negative-permittivity MM. For the four-cell structure, the filter size is 0.16 ?g × 0.26 ?g with the corresponding real size of 3.2 mm × 5.12 mm. It is found that the common-mode noise can be reduced over 10 dB from 3.8 to 7.1 GHz with the fractional bandwidth of 60% in the frequency domain, and is reduced over 50% for voltage amplitude in the time domain. More importantly, the differential signal integrity, in terms of insertion loss and group delay in the frequency domain and eye diagrams in the time domain, is not degraded within the wide stopband. To our best knowledge, it is the first broadband common-mode filter designed for gigahertz differential signals based on the concept of MM TL with most compact size.

160 citations


Journal ArticleDOI
TL;DR: In this article, a balanced dual-band and wide-stopband single-band balanced bandpass filters with high selectivity and common-mode suppression are presented. But the authors do not consider the effect of SIR loaded with SIR elements.
Abstract: Novel dual-band and wide-stopband single-band balanced bandpass filters with high selectivity and common-mode suppression are presented in this paper. Stepped-impedance resonators (SIRs) are usually used for designing dual-band bandpass filters; however, they have a strong common-mode response when designing a balanced filter. To suppress the common-mode signal, a half-wavelength SIR loaded by a capacitor or a resistor has been introduced and theoretically analyzed. It is found that the capacitor can minimize the common-mode external quality factor, and the resistor can reduce the common-mode unloaded quality factor. With the use of this property, the common-mode response can be suppressed, whereas the differential-mode response is almost unaffected. This property can be easily verified by comparing the results of the balanced bandpass filters with and without loaded elements. To demonstrate the design idea, one balanced dual-band bandpass filter operating at 2.4 and 5 GHz and another balanced single-band bandpass filter with a wide stopband are designed. It was found that the common-mode suppression level of both filters can be greatly improved, and high selectivity is obtained by giving two differential-mode coupling paths.

145 citations


Proceedings ArticleDOI
14 Jun 2010
TL;DR: A new algorithm named SCAN (stopband cyclic algorithm new) is proposed to design unimodular sequences with spectral power suppressed in arbitrary bands and with low correlation sidelobes as well.
Abstract: One of the main objectives of cognitive radar is to adapt the spectrum of transmit waveforms to certain needs, such as avoiding reserved frequency bands or narrowband interferences. Besides spectral requirements, good correlation properties of the transmit waveforms are also desired in specific applications, such as range compression. Moreover, practical hardware constraints usually require the transmit waveforms be unimodular (i.e. only phase-modulated). In this paper, we propose a new algorithm named SCAN (stopband cyclic algorithm new) to design unimodular sequences with spectral power suppressed in arbitrary bands and with low correlation sidelobes as well. The SCAN algorithm, which starts from random initializations, can generate many sequences possessing similarly good properties. Furthermore, the SCAN algorithm is based on FFT (fast Fourier transform) operations and thus is computationally efficient, which facilitates long-sequence design and real-time waveform update.

136 citations


Journal ArticleDOI
TL;DR: In this article, a hybrid resonant circuit is proposed, which is a combination of a shunt and series resonant circuits, which achieves a lower resonant frequency as compared to the single shunt circuit and series circuit.
Abstract: A hybrid resonant circuit is proposed in this paper. The circuit is a combination of a shunt resonant circuit and series resonant circuit. With this combination, lower resonant frequency is achieved as compared to the single shunt and series resonant circuits. As a result, a compact resonator with smaller size can be achieved as compared to the conventional quarter- and half-wave resonators. Besides the size reduction, the proposed resonant circuit is able to introduce a transmission zero to improve the stopband suppression in filter design. Based on this circuit, a very compact interdigital coupled microstrip resonator is proposed in this paper. The resonator achieves a small length of nearly 1/10 guided wavelength (?g), which has a length reduction of 63% as compared to the conventional uniform quarter-wave resonator. By using the proposed resonator, a second-order bandpass filter with a small size of 0.144?g × 0.128?g and a fourth-order bandpass filter with a size of 0.217?g × 0.1?g are built based on the standard filter synthesis methods. Both good performance and miniaturization are achieved for the proposed filters, and the expected transmission zeros are also observed. In addition to the small filters, the proposed resonator is suitable for miniaturized balun bandpass filters. A novel configuration for a balun bandpass filter is proposed based on the aforementioned resonators. A second-order balun bandpass filter with a size of 0.26?g × 0.145?g and afourth-order balun bandpass filter with a size of 0.213?g × 0.203?g are reported in this paper. Both balun filters achieve good filtering performance, as well as excellent amplitude and phase imbalances, which are less than 1 dB and 1° in the passband, respectively.

96 citations


Journal ArticleDOI
TL;DR: In this article, a new type of compact wideband bandstop filter (BSF) with four transmission zero in the stopband is presented. And the proposed filter topology consists of a coupled line directional coupler connected in parallel to an interference transmission line.
Abstract: This work presents a new type of compact wideband bandstop filter (BSF) with four transmission zeros in the stopband. The proposed filter topology consists of a coupled line directional coupler connected in parallel to an interference transmission line. The filter characteristics can be easily controlled by the coupling factor of the coupled line coupler and the characteristic admittances of both the coupler and the transmission line. Design equations and curves are provided for the filter design. To validate the proposed topology, a compact microstrip BSF centered at 2.0 GHz with a measured 20 dB rejection bandwidth of 100% and sharp rejection characteristics is designed and built.

94 citations


Journal ArticleDOI
TL;DR: A fully printable chipless RFID tag on a 90-¿m-thin Taconic TF290 laminate is presented, which can easily be transferred to plastic and paper, suitable for mass deployment for low-cost items in trillions.
Abstract: A fully printable chipless RFID tag on a 90-?m-thin Taconic TF290 laminate is presented. The tag consists of two crosspolarized ultrawideband (UWB) antennas and a multiresonating circuit. The data encoding is performed in the multiresonating circuit, which is comprised of multiple stopband spiral resonators. The resonators are optimized to operate on flexible laminate using two optimization techniques. Since TF290 has similar characteristics to thin polymer laminates, the design can easily be transferred to plastic and paper, which are suitable for mass deployment for low-cost items in trillions.

87 citations


Journal ArticleDOI
TL;DR: In this article, a compact lowpass filter with two transmission zeros is presented, which can be adjusted easily to obtain a larger zero separation without the need to change the stepped-impedance unit.
Abstract: This letter presents a novel compact lowpass filter with two transmission zeros. By tap-connecting the stepped-impedance hairpin unit, two transmission zeros can be generated when an interdigital structure is introduced between the two low-impedance sections. Further, the two transmission zeros can be adjusted easily to obtain a larger zero separation without the need to change the stepped-impedance unit. Therefore, a sharp transition, an expanded stopband, a low insertion loss, and a compact size can be obtained simultaneously. Two filters with single and two asymmetric units are designed, fabricated, and tested. The measured results demonstrate good performance: compact size, low passband insertion loss, broad stopband, and sharp skirt characteristic.

85 citations


Journal ArticleDOI
TL;DR: In this article, a compact ultra wideband (UWB) bandpass filter with an ultra narrow notched band is proposed using a hybrid microstrip and coplanar waveguide (CPW) structure.
Abstract: A compact ultra-wideband (UWB) bandpass filter with an ultra narrow notched band is proposed using a hybrid microstrip and coplanar waveguide (CPW) structure. The CPW detached-mode resonator (DMR) composed of a quarter-wavelength (?/4) nonuniform CPW resonator with a short-stub and a ?/4 single-mode CPW resonator (SMCR) can allocate three split frequencies at the lower end, middle, higher end of the UWB passband. The conventional broadside-coupled microstrip/CPW structure is introduced to improve the bandwidth enhancement around the split frequencies, which leads to good UWB operation. To avoid the interferences such as WLAN signals, the ?/4 meander slot-line structure embedded in the DMR is employed to obtain the notched band inside the UWB passband. The design is then verified by experiment. Good passband and stopband performances are achieved. Specifically, the fabricated filter has a 10 dB notched fractional bandwidth (FBW) of 2.06% at the notched center frequency of 5.80 GHz.

83 citations


Journal ArticleDOI
TL;DR: In this article, a bandpass filter with improved upper stopband performance using a defected ground structure (DGS) is presented, which is composed of seven DGSs that are positioned under the input and output microstrip line and coupled double step impedance resonator (CDSIR).
Abstract: A novel ultra-wideband (UWB) bandpass filter (BPF) with improved upper stopband performance using a defected ground structure (DGS) is presented in this letter. The proposed BPF is composed of seven DGSs that are positioned under the input and output microstrip line and coupled double step impedance resonator (CDSIR). By using CDSIR and open loop defected ground structure (OLDGS), we can achieve UWB BPF characteristics, and by using the conventional CDGSs under the input and output microstrip line, we can improve the upper stopband performance. Simulated and measured results are found in good agreement with each other, showing a wide passband from 3.4 to 10.9 GHz, minimum insertion loss of 0.61 dB at 7.02 GHz, a group delay variation of less than 0.4 ns in the operating band, and a wide upper stopband with more than 30 dB attenuation up to 20 GHz. In addition, the proposed UWB BPF has a compact size (0.27?g ~ 0.29?g , ?g : guided wavelength at the central frequency of 6.85 GHz).

Journal ArticleDOI
TL;DR: In this article, a microstrip lowpass filter with quasi-elliptic response is proposed, where a coupled capacitor between adjacent radial-shape patches is introduced in interdigital form.
Abstract: A compact microstrip lowpass filter with quasi-elliptic response is proposed. To achieve compact design, both symmetrically loaded radial-shape patches and meandered main transmission line are adopted. To realise the quasi-elliptic response and strengthen the roll-off sharpness for the filter, a coupled capacitor between adjacent radial-shape patches is introduced in interdigital form. Furthermore, the adoption of radial-shape patches and the interdigital structure can introduce both serial and parallel resonance in the circuit. Thus, a wide stopband with 7th harmonic suppression is achieved. A demonstration filter with 3 dB cutoff frequency at 1.18 GHz has been designed, fabricated and measured. Results show that a relative stopband bandwidth of 132.3 (referred to a suppression degree of 15 dB) is obtained while achieving a high figure-of-merit of 11543.

Journal ArticleDOI
TL;DR: In this paper, a novel ultra wideband (UWB) bandpass filter using two shorted coupled lines and a 270° transversal transmission line is proposed, which achieves good impedance matching, UWB passband and wider upper stopband.
Abstract: A novel ultra-wideband (UWB) bandpass filter using two shorted coupled lines and a 270° transversal transmission line is proposed. The two shorted coupled lines are utilized to realize 180° phase inversion, while a folded transversal transmission line of 270° is introduced to perform as another power transmission path. Good impedance matching, UWB passband and wider upper stopband can be achieved. One prototype is fabricated for demonstration, good agreement is observed between simulated and measured performances of the UWB filter, indicating a fractional bandwidth of 124.6% (3-11.6 GHz).

Journal ArticleDOI
TL;DR: In this paper, a 1 GHz power divider with enhanced spurious suppression is proposed, which has a simple implementation with moderate line impedance, flexible layout design and extended stopband bandwidth with three controllable transmission zeros.
Abstract: This paper presents a novel design of a microwave power divider with enhanced spurious suppression. The proposed circuit features simple implementation with moderate line impedance, flexible layout design, and extended stopband bandwidth with three controllable transmission zeros. Moreover, explicit closed-form expressions are available for the evaluation of circuit parameters. For verification, the simulated and measured results of a 1-GHz power divider implemented on microstrip are shown.

Journal ArticleDOI
TL;DR: In this article, a stepped-impedance resonator and stubs are used to achieve good stopband suppression attributed from the existence of transmission zeros in millimeter-wave bandpass filters.
Abstract: This paper presents compact CMOS millimeter-wave bandpass filters based on a new stepped-impedance technique by incorporating a grounded pedestal into the microstrip line. The characteristic impedance of a microstrip line can be effectively changed by varying both the height of pedestal and the width of line. Therefore, the stepped-impedance resonators and stubs can be realized in the compact three-dimensional forms in CMOS. Two millimeter-wave bandpass filters were designed by using the new stepped-impedance resonators and stubs. Their chip sizes are significantly miniaturized to 0.37 x 0.2 mm2, equivalently 0.012 λg2 . The first chip filter has the insertion loss of 3.1-3.4 dB in 59-71 GHz and the second filter has the insertion loss of 3.5-3.8 dB in 53-64 GHz. Both chip filters have good stopband suppression attributed from the existence of transmission zeros.

Journal ArticleDOI
TL;DR: In this paper, two bandpass filters with wide out-of-band suppression using multiple different resonators and discriminating coupling are presented, which can obtain 30 dB rejection level in the stopband from 1.2f0 to 3.8f0.
Abstract: This letter presents two bandpass filters with wide out-of-band suppression using multiple different resonators and discriminating coupling. By utilizing half- and quarter-wavelength resonators, the second harmonic can be eliminated. Discriminating coupling is used to obtain zero coupling coefficient at the third harmonic, whereas the coupling in the passband can be tuned to desired values. The proposed filter could obtain 30 dB rejection level in the stopband from 1.2f0 to 3.8f0. Meanwhile, the filter is simple to design and easy to fabricate. The theoretical analysis of the proposed filter is given and two demonstration filters are fabricated and measured. The simulated and measured results are presented and good agreements are observed, which confirm the proposed method.

Journal ArticleDOI
TL;DR: In this article, a millimeter-wave 35 GHz bandpass filter using coplanar waveguide structure is fabricated in a 0.18-m standard complimentary metal oxide semiconductor process.
Abstract: A novel millimeter-wave 35-GHz bandpass filter using coplanar waveguide structure is fabricated in a 0.18-?m standard complimentary metal oxide semiconductor process. The conductor-backed half-wavelength resonators are utilized to realize stopband characteristics at desired frequencies. A series LC resonant circuit can generate one transmission zero located at 58 GHz. It is also observed that the parasitic effect can create another transmission zero at 80 GHz. Furthermore, the transmission zero at 66 GHz is designed with the use of a shorter conductor-backed resonator. The selectivity of the proposed filter is much improved. Without including the dummy metal, the chip size of the proposed filter is 0.225 × 0.55 mm2. The good agreement between simulation and measurement is obtained.

Journal ArticleDOI
TL;DR: In this paper, the dispersion characteristics of the quasi-transverse electromagnetic modes that propagate along the ridges or strips, including their lower and upper cut-off frequencies, were investigated.
Abstract: This study presents Green's functions of parallel-plate structures, where one plate has a smooth conducting surface and the other an artificial surface realised by a one-dimensional or two-dimensional periodic metamaterial-type texture. The purpose of the periodic texture is to provide cut-off of the lowest order parallel-plate modes, thereby forcing electromagnetic energy to follow conducting ridges or strips, that is, to form a gap waveguide as recently introduced. The Green's functions are constructed by using the appropriate homogenised ideal or asymptotic boundary conditions in the plane-wave spectral domain, thereby avoiding the complexity of the Floquet-mode expansions. In the special case of a single ridge or strip, an additional numerical search for propagation constants is needed and performed in order to satisfy the boundary condition on the considered ridge or strip in the spatial domain. The results reveal the dispersion characteristics of the quasi-transverse electromagnetic modes that propagate along the ridges or strips, including their lower and upper cut-off frequencies, as well as the theoretical decay of the modal field in the transverse cut-off direction. This lateral decay shows values of 50-100 dB per wavelength for realisable geometries, indicating that the gap waveguide modes are extremely confined. The analytical formulas for the location of the stopband of the lowest order parallel-plate modes obtained by small-argument approximation of the dispersion equation are also shown. To verify the proposed analysis approach, the results are compared with the results obtained with a general electromagnetic solver showing very good agreement.

Journal ArticleDOI
TL;DR: In this article, a dual-plane structure composed of both a microstrip and a defected ground structure (DGS) slot is employed to obtain quad-frequency responses and transmission zeros are introduced to split both passbands into two.
Abstract: An approach for designing a quad-band bandpass filter is presented. The dual-plane structure composed of both a microstrip and a defected ground structure (DGS) slot is employed to obtain quad-frequency responses. The slot, with interdigital shape in the DGS, is designed to obtain dual-frequency responses and transmission zeros are introduced to split both passbands into two. The equivalent-circuit model is derived for the filter. A filter with four passbands centring at 1.74, 2.09, 2.75 and 3.14 GHz is shown with a stopband attenuation greater than 20 dB over the frequency range from 3.38 to 7.70 GHz.

Journal ArticleDOI
TL;DR: In this paper, a novel compact resonator for LPF is proposed, composed of a circular hairpin resonator and a pair of coupled parallel stepped impedance resonators (SIRs) inside.
Abstract: A novel compact resonator for LPF is proposed in this paper. It is composed of a circular hairpin resonator and a pair of coupled parallel stepped impedance resonators (SIRs) inside. With the loaded SIRs, additional two transmission zeros can be introduced and adjusted easily to cancel the spurious responses for stopband extending, while do not change the fllter size. Filters using one and two of the new cells were designed and measured. The two-cell LPF has an insertion loss less than 0.6dB from DC to 1.6GHz, including attenuation of double SMA transitions at both sides of the circuit which is about 0.3dB and a wide i10dB stopband from 2.5 to 13GHz (corresponding to 146% normalized 10dB stopband), but has a size of only 0:129‚g £ 0:073‚g.

Journal ArticleDOI
TL;DR: In this article, an inductance-loaded Y-shaped resonator and its applications to ultra-wideband (UWB) bandpass filters have been presented based on the odd-and even-mode equivalent circuits, the resonant characteristics of the proposed microstrip resonator with various electrical length and admittance ratio values are investigated.
Abstract: Inductance-loaded Y-shaped resonator and its applications to ultra-wideband (UWB) bandpass filters have been presented in this paper. Based on the odd- and even-mode equivalent circuits, the resonant characteristics of the proposed microstrip resonator with various electrical length and admittance ratio values are investigated. The relationship between the external quality factor and the parameters of the coupling structure has been analyzed to give a design approach for the UWB filter. Two types of UWB bandpass filters are designed to demonstrate the practicality of the proposed resonator. To get tight coupling, the high-impedance parallel-coupled line has been used in the input/output of the first UWB bandpass filter. Both simulated and measured results show that the first UWB filter has a 10-dB return loss bandwidth of 5.6 GHz, a group delay variation of less than 0.3 ns, and a wide upper stopband with more than 20-dB attenuation up to 17.5 GHz. The multilayer technology is applied to the second UWB bandpass filter to provide tight coupling by using the broadside-coupled structures. The measured results show that the multilayer UWB filter exhibits excellent performance, including 1-dB insertion loss and 10-dB return loss bandwidths of 3.3-10.4 GHz with a minimum insertion loss of 0.45 dB at 6.85 GHz, as well as 3-dB insertion loss bandwidth and group delay variation < 0.22 ns over the entire UWB band.

Journal ArticleDOI
TL;DR: In this article, a wideband bandpass filter (WBPF) with excellent selectivity is proposed, which can achieve a competitive attenuation slope of 262.2 and 75.9 dB/GHz in the lower and upper passband transitions, respectively.
Abstract: A wideband bandpass filter (WBPF) with excellent selectivity is proposed. An equivalent circuit model of the new complementary split-ring resonator (CSRR)-based resonator with good wideband response is presented. A WBPF with strong passband selectivity and wide stopband can be achieved by the new resonators with a proper coupled scheme using the eighth-wavelength (λ/8) directly coupled parallel microstrip-lines. Specifically, the filter exhibits a competitive attenuation slope of 262.2 and 75.9 dB/GHz in the lower and upper passband transitions, respectively.

Journal ArticleDOI
TL;DR: In this paper, a simple method and structure to design a dual-band bandpass fllter (BPF) by using a dual feeding structure and embedded uniform impedance resonator (UIR) is presented.
Abstract: In this paper, a simple method and structure to design a dual-band bandpass fllter (BPF) by using a dual feeding structure and embedded uniform impedance resonator (UIR) is presented. In this structure, two passbands can be designed individually and several transmission zeros can be created to improve the band selectivity and stopband performance. The flrst passband is determined by the dual feeding structure and the second passband is determined by the UIR. Moreover, by using the inter coupling in the UIR, the performance of the second passband can be easily tuned without degrading the flrst passband. In order to verify the design concept, two fllter

Journal ArticleDOI
TL;DR: In this paper, a dual-wideband microstrip bandpass fllter with improved upper-stopband performance is presented, which uses E-shaped microstrip Stepped-Impedance Resonator (SIR) and input-output cross-coupling feed structure.
Abstract: A novel dual-wideband microstrip bandpass fllter (BPF) with improved upper-stopband performance is presented. With the use of some special structures such as E-shaped microstrip Stepped- Impedance Resonator (SIR) and input-output cross-coupling feed structure, this fllter can generate flve transmission zeros which are beneflcial for improving its frequency selectivity and upper-stopband performance. Finally the microstrip dual-wideband BPF has been simulated, fabricated and measured. Measurement results show that the two passbands are centered at 3.7GHz and 5.8GHz with the fractional bandwidth of 31% and 13% respectively. Meanwhile more than 50% relative upper-stopband bandwidth with 20dB rejection has been realized. The simulated and measured results are in good agreement.

Journal ArticleDOI
TL;DR: A method for miniaturization of filters based on curved waveguide Bragg gratings, so that long structures can be packed into a small area on a chip, which eliminates the stitching errors introduced in the fabrication process.
Abstract: We propose a method for miniaturization of filters based on curved waveguide Bragg gratings, so that long structures can be packed into a small area on a chip. This eliminates the stitching errors introduced in the fabrication process, which compromise the performance of long Bragg gratings. Our approach relies on cascading curved waveguide Bragg gratings with the same radius of curvature. An analytical model for the analysis of these devices was developed, and a filter based on this model was designed and fabricated in a silicon on insulator platform. The filter had a total length of 920μm, occupied an area of 190μm×114μm, and exhibited a stop band of 1.7nm at 1.55μm and an extinction ratio larger than 23dB.

Journal ArticleDOI
TL;DR: In this article, the authors presented a tunable combline bandpass and bandstop filter using a dual-band circuit with wide passband and integrated narrow stopband and measured results showed that the bandwidth remained constant at 30 MHz as the filter was tuned from 3.22 GHz to 3.66 GHz.
Abstract: New methods for the design of tunable combline bandpass and bandstop filters are presented. The first part of this paper presents a tunable bandstop filter designed using a dual-band circuit with wide passband and integrated narrow stopband. A prototype has been constructed and measured results shows that the bandwidth remained constant at 30 MHz as the filter was tuned from 3.22 GHz to 3.66 GHz. The second part of this paper presents a tunable bandpass filter designed using a dual-band circuit with both wide passband and stopband. The response corresponds to two narrow passbands, where the lower passband bandwidth and center frequency can be tuned. A prototype has been constructed and measured results demonstrate wide centre frequency tuning range and over 300% bandwidth tuning without the need for coupling adjustment.

Journal ArticleDOI
TL;DR: In this paper, a microstrip lowpass filter with an ultra-wide stopband is proposed to achieve wide stopband suppression and compact size, both symmetrically loaded resonant patches and meander transmission line are adopted.
Abstract: A compact microstrip lowpass filter with an ultra-wide stopband is proposed. To achieve wide stopband suppression and compact size, both symmetrically loaded resonant patches and meander transmission line are adopted. A demonstration filter with 3 dB cutoff frequency at 1.3 GHz has been designed, fabricated and measured. The proposed filter also exhibits a very wide stopband of 152%, and is able to suppress the eleventh-harmonic response together with a small size of 0.12λg × 0.071λg, where λg is the guided wavelength at 1.3 GHz.

Journal ArticleDOI
TL;DR: In this article, an asymmetric SIR structure was proposed to increase the degree of freedom in the dual-passband bandwidth design, and the transmission zero of the coupling stage could be used to suppress the unwanted higher order spurious responses.
Abstract: A systematic design method for microstrip bandpass filters with both dual-passband response and multi-spurious suppression is proposed in this letter. The filter is composed of stepped impedance resonators (SIRs). A novel asymmetric SIR structure is proposed to effectively increase the degree of freedom in the dual-passband bandwidth design. As a consequence, the transmission zero of the coupling stage could be used to suppress the unwanted higher order spurious responses. A complete design procedure considering both the synthesis of passband responses and the suppression of spurious responses is also depicted in detail. A fifth order filter is designed and fabricated to demonstrate this idea. The measured results show that the upper stopband can have an attenuation level near 30 dB up to more than 20 GHz (8.16 f 0).

Journal ArticleDOI
TL;DR: In this article, a high performance diplexer is designed and fabricated for Global Positioning System (GPS) and wireless local area network (WLAN) applications simultaneously, which mainly comprises two dual-mode ring bandpass fllters (BPFs), operated at 1.575GHz and 2.4GHz, respectively.
Abstract: In this paper, a high performance diplexer is designed and fabricated for Global Positioning System (GPS) and wireless local area network (WLAN) applications simultaneously. The diplexer mainly comprises two dual-mode ring bandpass fllters (BPFs), operated at 1.575GHz and 2.4GHz, respectively. By using the stepped-impedance resonator (SIR) in the BPFs, the size reduction and wide stopband from 2.8GHz to 6GHz are obtained. Moreover, several transmission zeros are located at the passband edges, thus improving the passband selectivity. Due to impedance matching between two BPFs, a high

Journal ArticleDOI
TL;DR: In this article, a multiresonant metamaterial composed of asymmetric triangular electromagnetic resonators (ATERs) is presented, and the parametric retrieval and eigenmode analysis based on simulations and experiments are utilized to gain an insight into the resonance mechanisms.
Abstract: A new multiresonant metamaterial composed of asymmetric triangular electromagnetic resonators (ATERs) is presented in this letter. The ATERs' structure has one electric resonance and two magnetic resonances. The parametric retrieval and eigenmode analysis based on simulations and experiments are utilized to gain an insight into the resonance mechanisms. A parallel-plate waveguide (PPW) measurement system is introduced to detect the characteristics of multiresonant ATERs. The transmission stopband obtained by the PPW system effectively reveals that one resonance is caused by an electric mode and the other two resonances are caused by magnetic modes.