EBG-Embedded Multiple-Mode Resonator for UWB Bandpass Filter With Improved Upper-Stopband Performance

An electromagnetic bandgap (EBG) embedded multiple-mode resonator (MMR) is proposed to constitute an upper-stopband-improved and size-miniaturized ultra-wideband (UWB) bandpass filter (BPF). This EBG-embedded MMR is studied to relocate its first three resonant modes within the 3.1-10.6GHz passband, whereas placing its 4th resonant mode at the coupling transmission zero of interdigital coupled-lines that drive this MMR at two sides. Meanwhile, the fifth resonant mode is rejected by virtue of the bandstop behavior of the EBG itself. Thus, a modified UWB BPF with widened upper-stopband, sharpened upper rejection skirt and lowered loss in the passband is finally constituted, designed and fabricated. The measured results demonstrate that the insertion loss is lower than 1.0 dB in the passband (4.0-10.6GHz) and higher than 15.0dB in the upper-stopband (12.0 to 20.0GHz) while the group delay variation in the passband is less than 0.2ns     

Compact UWB bandpass filter using ring open stub loaded multiple-mode resonator

A novel ultra-wideband (UWB) bandpass filter with a compact size, improved upper-stopband performance and reduced radiation loss has been studied and designed using a multiple-mode resonator (MMR). The MMR is formed by attaching three pairs of ring open stubs in shunt to a high impedance microstrip line. By simply adjusting the radius of the circles of the ring stubs, the resonant modes of the MMR can be roughly allocated within the 3.1?10.6 GHz UWB band while suppressing the spurious harmonics in the upper-stopband. Meanwhile, the insertion loss is higher than 20.0 dB in the upperstopband from 11.7 to 33.5 GHz in simulation. Finally, the filter is fabricated and measured. The EM-simulated and measured results are presented and excellent agreement between them is obtained.     

Compact UWB Bandpass Filter With Improved Upper-Stopband Performance

In this letter, a novel ultra-wideband (UWB) bandpass filter with compact size and improved upper-stopband performance has been studied and implemented using multiple-mode resonator (MMR). The MMR is formed by attaching three pairs of circular impedance-stepped stubs in shunt to a high impedance microstrip line. By simply adjusting the radius of the circles of the stubs, the resonant modes of the MMR can be roughly allocated within the 3.1-10.6 GHz UWB band while suppressing the spurious harmonics in the upper-stopband. In order to enhance the coupling degree, two interdigital coupled-lines are used in the input and output sides. Thus, a predicted UWB passband is realized. Meanwhile, the insertion loss is higher than 30.0 dB in the upper-stopband from 12.1 to 27.8 GHz. Finally, the filter is successfully designed and fabricated. The EM-simulated and the measured results are presented in this work where excellent agreement between them is obtained.     

Short-circuited CPW multiple-mode resonator for ultra-wideband (UWB) bandpass filter

An ultra-wideband (UWB: 3.1-10.6 GHz) bandpass filter (BPF) on coplanar waveguide (CPW) is proposed, designed and implemented. A nonuniform CPW multiple-mode resonator with short-circuited ends is constructed and its first three resonant modes are properly allocated around the lower-end, center and higher-end of the specified UWB band. This CPW resonator is then driven at two ends by two parallel-coupled CPW lines with dispersive inductive coupling degree. By properly reallocating the enhanced coupling peak toward the UWB's center, a five-pole CPW BPF with one full-wavelength can be eventually constituted. Its UWB bandpass performance is characterized and optimized on the basis of a simple transmission-line network. Predicted results are confirmed by experiment. Measured results achieve the insertion loss <1.5dB and group delay variation <0.35ns in the realized 3.3 to 10.4GHz UWB passband.     

A Novel Wideband Bandpass Filter Using A Cross-Shaped Multiple-Mode Resonator

A novel wideband bandpass filter (BPF) using a cross-shaped microstrip multiple-mode resonator (MMR) is presented in the letter. The MMR is composed of a section of open-ended microstrip-line and a pair of short-ended stubs. Its three resonant modes are used to construct the passband of the proposed BPF. And two coplanar waveguides are used as the input/output transmission-lines to improve the coupling between the MMR and input/output transmission-lines. The filter has been investigated numerically and experimentally. Both simulated and measured results show that the filter has a good performance, including controllable bandwidth from 66% to 114%, low insertion loss (lower than 0.78 dB), and a small group delay variation.     

Ultra wideband bandpass filter with dual-notched bands using stub-loaded rectangular ring multi-mode resonator

This paper presents a new ultra wideband (UWB) bandpass filter (BPF) with dual-notched bands (at 5.2/5.7 GHz) using the stub-loaded rectangular ring multi-mode resonator (MMR). The proposed resonator consists of the dual embedded open-circuited stubs for introducing the dual notch bands and connected with a stub-loaded rectangular ring structure for controlling the two transmission zeros (at 3/11 GHz) at both sides of the UWB passband edge. This study mainly provides a simple method to design a UWB bandpass filter with high passband selectivity and dual-notched bands for satisfying the Federal Communications Commission (FCC-defined) indoor UWB specification. Experimental verification is provided and good agreement has been found between simulation and measurement.     

Ultra-wideband bandpass filter with hybrid microstrip/CPW structure

A novel ultra-wideband (UWB) bandpass filter (BPF) is presented using the hybrid microstrip and coplanar waveguide (CPW) structure. A CPW nonuniform resonator or multiple-mode resonator (MMR) is constructed to produce its first three resonant modes occurring around the lower end, center, and higher end of the UWB band. Then, a microstrip/CPW surface-to-surface coupled line is formed and modeled to allocate the enhanced coupling peak around the center of this UWB band, i.e., 6.85GHz. As such, a five-pole UWB BPF is built up and realized with the passband covering the entire UWB band (3.1-10.6GHz). A predicted frequency response is finally verified by the experiment. In addition, the designed UWB filter, with a single resonator, only occupies one full-wavelength in length or 16.9mm.     

Compact Ultra-Wideband Bandpass Filter Using Dual-Line Coupling Structure

This letter presents a novel compact ultra-wideband (UWB) microstrip bandpass filter with spurious response suppression. A dual-mode ring resonator is constituted to allocate its first two resonant frequencies in the UWB band, and the dual-line parallel-coupled structure is used in this compact UWB filter, which is expected to achieve much tighter coupling degree. Simulated and measured results are found in good agreement with each other, showing a wide passband from 4.9 to 10.9 GHz, 15 dB return loss bandwidth of about 5 GHz, minimum insertion loss of 0.49 dB at 7.3 GHz, and wide upper stopband with more than 20 dB attenuation up to 20 GHz.     

基于环形谐振器的平衡式带通滤波器

提出了一种基于多模环形谐振器实现的平衡式带通滤波器, 其主要由加载了电阻和短路枝节的环形谐振器和两对平衡端口构成.所提出的滤波器能够以单个谐振器获得差模的双模响应, 并且具有结构简单, 共模抑制高, 带宽可进行有限控制(4% ~ 9%)的优点.为验证理论预期的可实现性, 在RO4003C基板上设计了一个工作在1.87 GHz的平衡式带通滤波器.实验结果表明该滤波器的20-dB阻抗匹配带宽为8.9%, 中心频率处的插入损耗为0.86 dB, 在1 ~ 3 GHz频率范围内的共模抑制大于30 dB.     

一种新型超宽带带通滤波器的设计

针对超宽带(UWB)系统易受无线网络信号干扰及传统的超宽带带通滤波器阻带较窄,不能有效抑制谐波的问题,提出了一种新型的UWB带通滤波器,该滤波器由两级交指梳状耦合谐振器级联组成,通过增加耦合指的个数来实现陷波特性,然后在两个交指谐振器的中间添加一个槽线锥形谐振器,使该滤波器具有抑制高次谐波特性,达到拓宽高阻带的效果,同时由于槽线谐振器的加入,陷波频段的抑制电平进一步提高.实验结果证明,所设计的滤波器既能保证3.1～10.6 GHz频段内的插入损耗小于3 dB,陷波频段为5.7～5.8 GHz,陷波频段的抑制电平高达-43 dB,同时又能拓宽高频阻带.     

Planar microstrip UWB bandpass filter using U-shaped slot coupling structure

A compact planar microstrip UWB bandpass filter is proposed. It is realised by cascading a lowpass filter and a highpass filter. A transmission line with U-shaped slots coupled with two DGS units on the back of the circuit board has the characteristic of highpass, while a periodic uniform DGS array has the characteristic of lowpass. Combining these two structures, a new UWB bandpass filter (BPF) is fabricated and measured. Measured results show that the proposed BPF has wide bandwidth from 3.0 to 10.9 GHz, all the measured return loss less than 13 dB in the passband. The BPF achieves a wide stopband with 18 dB attenuation up to 18.0 GHz     

基于新型谐振器的超宽带带通滤波器

采用两个新型四阶阶梯阻抗谐振器设计出一种新型超宽带带通滤波器,四个1/4波长的耦合线被平行放置于输入输出端,起到增加耦合强度的作用,三个谐振频率被调整在超宽带带宽(3.1 GHz～10.6 GHz)内。通过优化后,该滤波器在通带内具有五个传输极点,频带宽度在3.6 GHz～10.5 GHz,通带内回波损耗优于15 dB,最小插入损耗为0.6 dB,满足超宽带的传输要求。仿真结果显示,文中设计的滤波器具有小型化、低插入损耗和较好的带外特性等优点。     

新型超宽带带通滤波器

提出了一种新型的短接环形多模谐振器,适合于构成超宽带带通滤波器。利用该多模谐振器的前三个谐振模式构成滤波器的整个通带．并提出通过改变多模谐振器阻抗比来控制该带通滤波器的相对带宽的方法。该结构具有易于级联的特性。通过级联可明显改善阻带特性。给出了一个单元以及三个单元级联后的滤波器结构以及通过仿真和实验获得的性能参数,验证了所设计的新型超宽带带通滤波器的有效性。     

Capacitive-Ended Interdigital Coupled Lines for UWB Bandpass Filters With Improved Out-of-Band Performances

This letter presents a novel ultra-wideband (UWB) microstrip bandpass filter on a microstrip line with improved out-of-band performances. A multiple-mode resonator (MMR) is first constituted to equally allocate its first three resonant frequencies in the 3.1–10.6-GHz UWB band. Two capacitive-ended interdigital coupled lines are then formed to assign their transmission zero towards the fourth-order resonant frequency of this MMR, thereby suppressing the first spurious passband. Moreover, two outer arms in the interdigital lines are properly tapered to compensate the phase imbalance or group delay near the UWB upper-end relying on extra capacitive-ended stubs. And finally, two UWB filters with one- and two-MMRs are designed and implemented to experimentally demonstrate the improved out-of-band performances, i.e., widened/deepened upper-stopband and sharpened rejection skirts outside the UWB passband.     

Compact Wide-Band Bandpass Filter Using Microstrip to Slotline Broadside-Coupling

In this letter, two quarter wavelength microstrip stubs with a shorted slot line resonator etched in the ground plane is used to design a compact wideband bandpass filter (BPF). Wideband characteristics are obtained using broadside-coupling between the stubs and the slot line. 3-dB fractional bandwidth (FBW) is varied by changing coupled line widths. The filter has the advantages of compactness, wide bandwidth, low passband insertion loss (IL), low group delay variation and ease of fabrication. One prototype fabricated filter has a FBW of 60.0% with a maximum passband IL of 0.9 dB and group delay variation of 0.40 nS. BPF occupying area is less than 0.19lambdagtimes0.20lambdag, where lambdag is the guided wavelength at midband frequency 2.5 GHz. Good agreement between measurements and simulations are obtained.     

Implementation of Compact UWB Bandpass Filter With a Notch-Band

An ultra-wideband (UWB) bandpass filter on microstrip line with notch-band, compact-size and improved upper-stopband performances is presented and implemented. A modified non-uniform resonator is at first formed by transversely attaching three pairs of impedance-stepped stubs. Its resonance behavior is thoroughly characterized so as to allocate the first three resonant frequencies within 3.1-10.6 GHz band while suppressing spurious harmonics in the upper-band. As this resonator is linked at two sides with two feed lines via interdigital coupled lines with enhanced coupling degree, a preferred UWB passband is realized. Then, one of two arms in the coupled-line sections is largely extended and folded, aiming to create a notch band at the frequency of 5.6 GHz by virtue of out-of-phase transmission cancellation. Two filter prototypes are optimized and fabricated to demonstrate the notch-band-included and upper-stopband-improved UWB bandpass performances.     

Parallel coupled-line bandpass filter with branch-line shape for g-band frequency

A parallel coupled-line planar bandpass filter (BPF) with branch-line shape using coplanar waveguide technology on GaAs substrate is presented. The unit parallel coupled-line BPF utilises a parallel coupled-line resonator with an open-ended stub which has suppression response of spurious band. Four unit parallel coupled-line BPFs are integrated with branch-line shape and open-circuit stubs on input and output ports are also integrated for improvement of rejection performance. The proposed fourth-order filter was fabricated on GaAs substrate with dielectric thickness of 50 m and gold thickness of 1.2 mum. The fabricated fourth-order BPF shows a 3 dB bandwidth from 177 to 209 GHz frequency range with insertion loss of 6.5 dB, rejection of 38 dB and return loss better than 12 dB. It has a high resolution fractional bandwidth of 17%.     

Design and analysis of a super compact wide-band bandpass filter based on metamaterial resonators

In this paper, a novel compact wide-band bandpass filter (BPF) with a wide frequency range is presented. This filter consisting of a multi-mode resonator (MMR) and four metamaterial unit-cells benefits from a very compact size. Unit-cells based on a complementary spiral resonator (CSR) including a metallic via, improve both upper and lower stopband rejection and compensate the insertion loss (I.L) within the passband altogether. This wide-band filter presents a 3-dB bandwidth of 7.7 GHz, ranging from 3 GHz to 10.7 GHz and the Insertion loss is less than 0.7 dB over the passband. The measured results are in good agreement with both the full-wave electromagnetic simulation and the proposed circuit model results. The dimension of the fabricated filter is 0.128 λ × 0.1 λ (i.e., 5.6 × 4.4 mm²). This filter is considerably compact compared to the other wide-band bandpass filters with the same substrate.     

基于E型谐振器的三陷波超宽带带通滤波器

针对超宽带系统中存在窄带信号干扰的问题,提出了一种加载E型谐振器的多模谐振器(Multimode Resonator,MMR)结构,采用内嵌开路枝节的方法设计了一款三陷波超宽带滤波器,并且通过调节内嵌开路枝节的长短,实现了双陷波的性能。该超宽带带通滤波器通带频带范围为3. 1~10. 2 GHz,通带内插入损耗小于1 d B,相对带宽为107%。其中,实现的三陷波滤波器的三个陷波中心频率分别为3. 8,5. 1和6. 6 GHz。通过调节内嵌开路枝节的长短,可以实现双陷波到三陷波之间的转换,仿真结果与理论分析一致。     

Compact UWB bandpass filter with improved upper-stopband performance

a compact microstrip-line ultra-wideband (UWB) bandpass filter (BPF) using aperture-backed interdigital coupled lines and a stub-loaded folded stepped-impedance resonator (SLFSIR) is presented. in the design, the first four resonant frequencies of this SLFSIR are properly adjusted to be placed evenly within the UWB while the fifth resonant frequency is raised above 16.0 GHz to improve upper-stopband performance. furthermore, the aperture-backed interdigital coupled lines can create a transmission zero to cancel the fifth resonant mode of the SLFSIR to make a wider upper-stopband as well as raising the coupling degree to relax the tight line spacing. after optimisation of this filter, good UWB bandpass behaviour is theoretically realised and experimentally confirmed.