Compact UWB Bandpass Filter Based on Signal Interference Techniques

This letter presents a new type of compact ultra-wideband (UWB) bandpass filter (BPF) based on interference techniques. The structure is formed by a short-ended coupled line coupler connected in parallel to a transmission line. The transmission and reflection zeros of the filter can be controlled through the analytical equations and rules given. To validate the suggested filter scheme, the design, fabrication and measurement of a microstrip UWB BPF is presented.      

Miniature CPW Parallel-Coupled Bandpass Filter Based on Inductive Loaded Coupled-Lines and Lumped-Element J-Inverters

This study presents a compact coplanar-waveguide (CPW) parallel-coupled bandpass filter (BPF) with good selectivity and stopband rejection. The inductive terminations are introduced to the conventional anti-parallel coupled-lines, and lumped-element J-inverters are employed, to achieve both size reduction and spurious suppression. Additionally, the inductive cross-coupling effect is introduced to obtain two transmission zeros to enhance the selectivity. Suitable equivalent-circuit model is also established as effective design tool. Specifically, this work demonstrates a compact cross-coupled fourth-order BPF in grounded-CPW configuration. Compared to the conventional filters, the proposed filters exhibit over 65% size reduction, improved selectivity, and wider stopbands up to four times the center frequency     

Analytical design of a microstrip UWB BPF with sharp rejection

This paper presents a new Ultra-WideBand (UWB) BandPass Filter (BPF) using half-wavelength (??/2) Stepped-Impedance Stub-Loaded Resonator (SISLR). Analytical equations derived by the even-odd mode analysis show the new filter has two tunable transmission zeros at both sides of the passband to provide a sharp rejection and seven transmission poles inside the passband to achieve U.S. UWB performance. For verification, a UWB BPF is designed, fabricated and measured. The measured results show that the fabricated filter has a -3 dB fractional bandwidth from 3.0 GHz to 10.9 GHz and its insertion loss less than 0.9 dB over the whole passband. Furthermore, the new filter exhibits a simple topology, sharp rejection, and deep stopband suppression.     

Small Ultra-Wideband (UWB) Bandpass Filter With Notched Band

A compact ultra-wideband (UWB) bandpass filter (BPF) with notched band has been proposed and implemented in this letter. H-shaped slot is studied and adopted to tighten the coupling of inter-digital capacitor in order to improve the BPF's performance. Three pairs of tapered defected ground structures (DGS) are formed to assign their transmission zeros towards the out of band signal, thereby suppressing the spurious passband. Combining these two structures we obtain a small sized UWB BPF. Meander line slot is developed to reject the undesired wireless local-area network (WLAN) radio signals. An experimental UWB filter with notched band was fabricated with 35% less length as compared to an embedded open-circuited stub. The measured BPF insertion loss is less than 1.0 dB throughout the pass band of 2.8 to 10.8 GHz, the variation of group delay less than 0.20 ns in this band except for the notched band, and a wide stopband bandwidth with 20 dB attenuation up to at least 20.0 GHz.     

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.     

Millimeter-Wave Ultra-Wideband Bandpass Filter Employing Dual-Mode Ring Resonators Fed by Step-Impedance Coupled Lines

This paper presents a novel millimeter-wave ultra-wideband (UWB) bandpass filter (BPF) based on microstrip dual-mode rectangular ring resonators. In order to get strong coupling between the input/output line and the dual-mode ring resonators, a step-impedance parallel-coupled structure is adopted for the design of the filter. On the other hand, transmission zeros are produced by the dual-mode resonator. As a consequence, the filter has low insertion-loss in its passband, sharp attenuation in its lower and upper stopbands and very wide stopbands. As an example, a filter with two dual-mode ring resonators is designed and fabricated. The measured frequency property of the fabricated filter shows good agreement with the simulated response.     

Dual band notched UWB-BPF based on hybrid microstrip-to-CPW transition

The research paper proposes a compact dual notched band ultra-wideband (UWB) bandpass filter (BPF). The basic architecture of the filter is developed using the hybrid microstrip-to-coplanar waveguide (CPW) technology, wherein a short circuited CPW in ground is coupled vertically via the dielectric to the microstrip lines on the top plane. The broadside alignment generates a three pole BPF with dual transmission zeros (TZs) on either passband/stopband edges which leads to minimum insertion loss passband and sharp roll-offs. Later, multiple spirals and split ring resonators (SRRs) are embedded in the CPW of the UWB filter to introduce the dual notches and widen the stopband respectively. The proposed filter is fabricated to justify its measured response. The proposed filter measures only 14.6 × 7.3 mm².     

A Narrow Bandwidth Microstrip Band‐Pass Filter with Symmetrical Frequency Characteristics

This letter proposes a band‐pass filter (BPF) with two transmission zeros based on a combination of parallel coupling and end coupling of half‐wave transmission lines. The fabricated BPF exhibited a narrow bandwidth and two transmission zeros near the pass‐band due to the end‐coupled and shielding waveguide. At the center operation frequency of 60 GHz, the 20 dB bandwidth of the BPF is 1.0 GHz, which is almost 2% of the center operation frequency, and the insertion loss is 3.12 dB. Two transmission zeros reach approximately 40 dB at 58.5 and 62.5 GHz. The simulation results almost agree with the measured results.     

Asymmetric dual-line coupling strip for multiple notched bands: Theory and implementation

An asymmetric dual-line coupling strip (ADLCS) can provide main two paths for the signals, which make it possible to generate multiple transmission zeroes. The detailed analysis of the ADLCS is proposed in this paper. Based on the microwave network theory, the equivalent circuit of the ADLCS is also developed. Moreover, the structural parameters of ADLCS are studied by calculations and simulations. The center frequencies and bandwidths of the notch bands can be controlled by tuning the structural parameters. Obviously, The ADLCS can be used in the ultra-wideband (UWB) bandpass filter (BPF) to generate multiple notch bands within the passband. To demonstrate the performance of the ADLCS with UWB filter, the structure is applied to the input and output (I/O) of the single-stage UWB Y-shaped BPFs. The proposed UWB Y-shaped BPF has been designed, fabricated, and measured. The measured results agree with the predicted ones closely. The two notch bands of the fabricated UWB Y-shaped BPF centered at 4.5 and 8.1 GHz have 10-dB rejection fractional bandwidths of about 5.6% and 5%, respectively.     

Fractal Dual-Mode Open-Loop Quasi-Elliptic Bandpass Filter with Source-Load Coupling

To realize the feature of small size and high selectivity, a microstrip miniature fractal quasi-elliptic bandpass filter (BPF) with two transmission zeros (TZs) near each skirt is investigated in this paper. The TZs are created by source-load coupling between the input and output E-shaped feeding structures. By using a dual-mode Minkowski fractal shorted stub loaded open-loop resonator, the proposed BPF achieved a size reduction of 97.5% compared with the conventional square dual-mode loop BPF. Even mode analysis is adopted to characterize the Minkowski structure. The frequency responses of the current BPF were simulated and measured with good agreement.     

New compact ultra wideband bandpass filter using modified multi-mode resonator

A new compact ultra wideband (UWB) bandpass filter (BPF) using modified multi-mode resonator (MMR) is presented. The filter consists of a multi-mode resonator with dual spur-lines for providing the dual notch bands at 5.2 and 5.8 GHz and connected with a stepped impedance structure for controlling the transmission zeros at lower and higher passband edge. The interdigital coupling input/output (I/O) lines are used for coupling enhancement. The |S₂₁|-magnitude and the frequencies of notch bands can be well determined by tuning the dimensions of the dual spur-lines. The designed procedures are discussed and good agreement between the measurement and EM simulation are compared.     

超宽带纳秒脉冲在带通滤波器中传输特性研究

根据超宽带(UWB)纳秒电磁脉冲的基本特性,采用模拟计算仿真与实验研究方法,研究了超宽带纳秒电磁脉冲信号通过微波接收机带通滤波器的时域、频域传输特性,初步认识了超宽带纳秒电磁脉冲通过带通滤波器传输特性规律,它是对传统连续波(CW)信号与脉冲调制信号通过微波带通滤波器传输特性技术的补充和完善。该研究成果为将来开发超宽带纳秒电磁脉冲在各类接收机中的应用提供技术基础。     

新型高选择性双模宽带带通滤波器设计

首先利用阶梯阻抗谐振器和交叉耦合馈线结构设计了一种带宽达73．2％新型双模带通滤波器。该谐振器在通带内产生两个可调模式,馈线结构在阻带对称产生两个传输零点。接着在馈线上加载短路线,使原有的两个传输零点向截止频率靠近,并在上阻带新增一个零点,从而在保持原滤波器通带性能的同时提高了频率选择性和上阻带特性。通过对比两个滤波器S参数进一步验证改进效果。最后制作测试了该短路线加栽的滤波器,仿真和实测结果吻合良好。     

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     

多带外传输零点微带带通滤波器设计

设计了一种梳状微带平行耦合线窄带带通滤波器,仅应用两腔结构就实现了带外5个传输零点.通过微带线开路枝节,平行耦合线结构,以及馈电位置和两个梳状线谐振器之间的耦合,在通带附近引入了3个传输零点;四分之一波长平行耦合线接地短路结构,在带外高频产生额外两个传输零点,进而可有效抑制零点频率附近的杂波干扰.实测结果表明,设计的滤...     

Switchable Embedded Notch Structure for UWB Bandpass Filter

A reconfigurable ultra-wideband (UWB) bandpass filter (BPF) with switchable notch for UWB system is presented. The UWB BPF is embedded with two identical switchable notch structures, in which PIN diodes are used for electronic switching. A bias circuit for UWB applications was investigated and designed to control the state of PIN diodes in order to activate or deactivate the notch without an affect on the response of the BPF. A demonstrator for this type of switchable notch UWB filter is designed and fabricated. Simulated and measured results are described.      

A Compact Ultra-Wideband Bandpass Filter Based on Split-Mode Resonator

A compact ultra-wideband (UWB) bandpass filter is proposed based on the coplanar-waveguide (CPW) split-mode resonator. By suitably introducing a short-circuited stub to implement the shunt inductance between two quarter wavelength CPW stepped-impedance resonators, a strong magnetic coupling may be realized so that a CPW split-mode resonator may be constructed. Moreover, by properly designing the dual-metal-plane structure, one may accomplish a microstrip-to-CPW feeding mechanism to provide strong enough capacitive coupling for bandwidth enhancement and also introduce an extra electric coupling between input and output ports so that two transmission zeros may be created for selectivity improvement. The implemented UWB filter shows a fractional bandwidth of 116% and two transmission zeros at 1.705 and 11.39 GHz. Good agreement between simulated and measured responses is observed.     

Design of fractal-based CMOS bandpass filter for WirelessHD system

We proposed a fractal-based dual-mode bandpass filter (BPF) using a standard CMOS process for application of 60 GHz WirelessHD system. We first investigated the effect of coupling feedlines of I/O ports set at different layer of M3 and M4 layer on the transmission loss of the resonator, and verified the nature coupling of fractal-based dual-mode filter. Experimental result shows that the designed filter with a fractional-bandwidth (FBW) of 23%, an insertion loss about 7 dB and return loss larger than 10 dB. Additionally, two transmission zeros are appeared at the passband edges, thus much improve the selectivity of the proposed CMOS BPF. The result indicates that fractal-based structure is feasible and can meet the requirement in the mm-wave application.     

Novel Broadband Bandpass Filters Using Y-Shaped Dual-Mode Microstrip Resonators

A Y-shaped dual-mode microstrip bandpass filter (BPF) with input-output cross-coupling is presented. The characteristic of the Y-shaped dual-mode resonator has been investigated. The resonance frequencies of the degenerate modes can be adjusted easily to satisfy the bandwidth of the BPF. A parallel-coupling feed structure with a cross coupling has been used to generate two transmission zeros at the lower and upper stopband, which can improve the out-of-band performance. A broadband dual-mode microstrip BPF has been designed, fabricated, and measured. The simulated and measured results are in agreement generally. Within the 3.1 to 5.4 GHz bandwidth, the measured insertion loss, return loss and group delay variation are below 0.5 dB, above 15 dB, and below 0.2 ns, respectively.      

An Extended Doublet Substrate Integrated Waveguide (SIW) Bandpass Filter With a Complementary Split Ring Resonator (CSRR)

An “extended doublet” bandpass filter (BPF) is proposed using a substrate integrated waveguide (SIW) cavity with a complementary split ring resonator (CSRR) etched on its top metal plane. Thus, a single-layer BPF with two transmission zeros is realized successfully, with no additional area or layers occupied. The measured and simulated S-parameters of the filter are presented to show its predicted performance, with good agreements obtained between them.