Design of a Novel Bandpass Filter in Millimeter-Wave Band

In this paper, a novel Bandpass Filter (BPF) combining microstrip parallel-coupled with end-coupled resonators is proposed. The filter not only allows the cross coupling to be realized but also makes itself compactness. At 35GHz, such a filter is designed and experimental results are discussed.     

一种基于多模谐振器的超宽带带通滤波器设计

基于多模谐振器(MMR)理论,采用微带线-槽线混合结构,通过增加输入、输出之间耦合提高频率选择性,设计了一种结构紧凑体积小,频率选择性高的超宽带带通滤波器。利用电磁仿真软件HFSS对设计结果进行了仿真。仿真结果表明:该滤波器通带覆盖了3.5~10.4 GHz之间的频段,并具有较好的带内带外性能。对该滤波器进行了实物加工和测试,实测结果与理论分析和仿真结果吻合良好,该滤波器拥有较好的性能,可应用于超宽带无线通信系统。     

基于DSCSRR带通滤波器设计

为提高带通滤波器的选择特性,文章基于逆开口谐振环(CSRR)的构造思路,首先提出一种菱形逆开口谐振环(DSCSRR),并对其左手特性加以证明;然后详细研究了改变其结构参数对DSCSRR传输特性的影响程度;最后设计了一款基于DSCSRR带通滤波器并对所设计的滤波器进行了实物加工和实验测量,测量结果与仿真结果表明,所设计滤波器的中心频率为4.02GHz,选择特性为170dB/GHz,带内抑制小于15dB。该新型滤波器不仅具有选择特性高,而且具有体积小、设计简单等优点。     

Calibration of optimized minimum inductor bandpass filter with controllable bandwidth and stopband rejection

A calibration methodology for the optimized minimum inductor (OMI) bandpass filter (BPF) to compensate passive components' inherent loss, such as resistances and reactances, is presented. OMI BPF prevails conventional elliptic and Chebyshev BPFs by introducing fewer inductors for the same stopband rejection requirement. Given design specifications (bandwidth, stopband rejection) at a specific center frequency, the calibration flow optimizes the approach to offset the inaccuracy of center frequency, bandwidth, and stopband rejection due to the discrepancy between the actual and ideal prototype passive components. Two OMI BPF designs before and after calibration are presented for demonstration and comparison. They are 1) a 3rd order centered at 2.388 GHz, 35.54% fractional bandwidth (FBW), 29.97 dB stopband rejection, and 2) a 7th order centered at 2.333 GHz, 17.40% FBW, 62.29 dB stopband rejection.     

A compact planar ultra-wideband bandpass filter with multiple resonant and defected ground structure

A compact bandpass filter with dumbbell shape Defected Ground Structure (DGS) operating on ultra wide pass band (UWB – 3.1 to 10.6 GHz) is proposed. It is based on hybrid microstrip coplanar waveguide (dual sided metal) structure. A Multiple Resonant Structure (MRS) is constructed using coplanar waveguide (CPW) planar transmission line. The MRS makes the resonance using quarter wavelength and half wavelength open-ended CPW. The equispaced three resonances at lower (3.1 GHz), center (6.85 GHz) and higher edge (10.6 GHz) of the whole Ultra Wide Band is achieved using CPW MRS. To make the band as flat as possible, two more resonances are introduced using quarter wavelength microstrip patches on top of the commonly shared substrate, so the proposed filter becomes a five pole bandpass filter. A dumbbell shaped defected ground structure on either side of CPW MRS improves the return loss almost less than 20 dB over the whole UWB passband. The simulated results of proposed filter show good transmission response within passband and good rejection in out of the band. The simulated and measured results are very close to each other which proves the efficacy of proposed design.     

基于缺陷地抑制高阶谐波的带通滤波器设计

采用微带线设计的平行耦合滤波器(MCL-BPF)在通带以外往往产生谐波,出现寄生频段。利用缺陷地结构(Defected Ground Structure,DGS)的单极点带阻特性和慢波效应可以改善寄生通带,抑制谐波输出。对2.4GHz的传统微带平行耦合滤波器和改进型带通滤波器进行了仿真设计与加工测试。实测结果与仿真数据良好吻合,所提出基于斜哑铃型DGS的带通滤波器(S-DGS-BPF)可抑制至四阶谐波,抑制度达到-22dB以下,阻带为3-10GHz,中心频率处回波损耗为-26.93dB。并且改进型滤波器的尺寸缩小了约10%。     

Circularly polarized co-designed filtering annular slot antenna

In this paper, a compact circularly polarized co-designed filtering annular slot antenna (ASA) is proposed. The antenna comprises a distributed capacitor-loaded annular slot radiator to produce circular polarization (CP) radiation, which is seamlessly integrated with a microstripline bandpass filter (BPF) to enhance out-of-CP-band suppression. Two tightly coupled arc branches protruding into the annular slot are used to provide the required perturbation capacitance. The filter is designed by employing three concentric arc-shaped coupled microstripline resonators. The ground plane is shared by the annular slot radiator and the filter to reduce size occupation. It is found that the proposed antenna can not only yield high frequency selectivity, but also obtain widened CP bandwidth under the assistance of the filtering circuit. An antenna prototype has been fabricated and measured, showing that the antenna achieves a 10 dB return loss impedance bandwidth of around 13.7%, enclosing a 3 dB axial ratio (AR) bandwidth of more than 10.6%. Details of design considerations and experimental results are presented and discussed.     

Compact multilayer dual-band bandpass filter design using stepped impedance resonators

Compact dual-band bandpass filter (BPF) for the 5th generation mobile communication technology (5G) radio frequency (RF) front-end applications was presented based on multilayer stepped impedance resonators (SIRs). The multilayer dual-band SIR BPF can achieve high selectivity and four transmission zeros (TZs) near the passband edges by the quarter-wavelength tri-section SIRs. The multilayer dual-band SIR BPF is fabricated on a 3-layer FR-4 substrate with a compact dimension of 5.5 mm ×5.0 mm ×1.2 mm. The measured two passbands of themultilayer dual-band SIR BPF are 3.3 GHz -3.5 GHz and 4.8 GHz -5.0 GHz with insertion loss (IL) less than 2 dB respectively. Both measured and simulated results suggest that it is a possible candidate for the application of 5G RF front-end at sub-6 GHz frequency band.     

DUAL MODE WIDEBAND BAND-PASS FILTER WITH NOTCHED BAND FOR COMMUNICATION SYSTEM

This paper presents a planar microstrip wideband dual mode Band-Pass Filter (BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz.The dual mode band-pass filter consists of a ring resonator with ...