应用于WLAN／WiMAX的新型双模双通带微带滤波器

提出了一种新型应用于WLAN／WiMAX的对称T型开路支节加载的双模双通带滤波器,并对其进行了奇偶模分析,电场分布和电流分布分析。该滤波器的两个通带分别由奇模和偶模产生,且具有3个传输零点,带内插损分别为O．76dB／1．13dB,带内反射分别为-19．2dB／-15．1dB,在3．75—7．33GHz内,其衰减达到-20dB以下,具有高选择性和宽阻带的特性,且滤波器的卖测结果与仿真结果非常吻合。该双模滤波器具有非常小的尺寸,大小为14．03minx31．48mm,即0．15λg×0．34λg,所以该双模滤波器在工程领域非常具有应用价值。     

A novel self-coupled dual-mode ring resonator and its applications to bandpass filters

A novel dual-mode ring resonator with self-coupled segments, called a self-coupled ring resonator, is proposed. The self-coupling between ring segments provides the same mode perturbation effect as the conventional methods of adding stub, cutting notch, or varying line impedance on the ring resonator. The mode perturbation and transmission-zero generation due to the self-coupling effect are analyzed with the even-odd mode theory. The self-coupled ring resonator can have the capacitive or inductive perturbation simply by controlling the impedance ratio and coupling coefficients of self-coupled sections. For both perturbation cases, the transmission zeros exist at even multiples of the passband center frequency, resulting in wide stopband range. Also, only for the capacitive perturbation case, two transmission zeros are found on both sides of the passband, which brings a pseudo-elliptic bandpass response. In comparison with the regular uniform ring resonator, the self-coupled ring resonator takes shorter ring length, giving the compact size feature when applied to a bandpass filter design. A 2.45-GHz low-temperature co-fired ceramic bandpass filter based on the self-coupled ring resonator was designed to verify the proposed theory.     

A compact low-profile dual-band antenna for WLAN and WAVE applications

A compact and low-profile patch antenna with a simple structure is presented for the wireless local-area network (WLAN) and the wireless access in the vehicular environment (WAVE) applications. The proposed antenna with an overall size of only 23 mm × 25 mm is fed by a coplanar waveguide (CPW), and yields 10-dB impedance bandwidths of about 250 MHz centered at 2.44 GHz and of about 22% ranging from 5.13 to 6.38 GHz suitable for the WLAN 2.4/5.2/5.8 GHz and the WAVE 5.9 GHz (IEEE 802.11p) applications. Also, good dipole-like patterns and high average antenna gain of ≥2.3 dBi over the operating bands have been obtained. In this design, resonance can be effectively controlled by simply tuning the shaped slots on the patch. Mechanism of mode excitations and effect of the added slot's length on resonance for the proposed antenna are examined and discussed in detail. The experimental results have validated the proposed design as useful for modern mobile communication.     

CPW-fed compact monopole antenna for dual-band WLAN applications

A compact CPW-fed monopole antenna is proposed for dual-band wireless local area network (WLAN) operations. The proposed antenna, which consists of two strips, has compact size of 20/spl times/15.5/spl times/1.6 mm/sup 3/ including the ground. The proposed antenna effectively covers both 2.4 GHz (2.4-2.484 GHz) and 5 GHz (5.15-5.825 GHz) bands. The measured peak gains are 1.3 dBi at 2.44 GHz and 2.8 dBi at 5.32 GHz.     

Design of compact dual-band switchable bandpass filter

A compact dual-band switchable bandpass filter is designed using two centrally-loaded open-loop resonators and six pin blocks. The pin diodes are loaded at the zero-voltage points of odd and even modes along the microstrip resonators, such that the two passbands operating at odd and even modes can be individually switched on or off. The isolations for the two passbands are greater than 20 dB.     

A novel microstrip dual-mode bandpass filter with harmonic suppression

A novel dual-mode microstrip bandpass filter (BPF) with harmonic suppression is presented in this letter. The filter is composed of a perturbed square-ring resonator and two end-open L-shaped microstrip lines for the input and output of the resonator. The harmonic suppression of the BPF may be realized by choosing a proper length for the L-shaped microstrip line. The BPF has been investigated numerically and experimentally. Measured results show that the stop-band of the filter is increased up to near the third-order harmonic of the square-ring resonator due to harmonic suppression, and the rejection level is kept below -27dB.     

采用新型介质集成波导腔的小型双频滤波器

提出了一种新式的横电磁波-基片集成波导(TEM-SIW)谐振腔。这种TEM-SIW谐振腔由经典的基片集成波导(SIW)腔发展而来。通过在SIW腔的中心位置加入短路销钉,将SIW腔体的上金属平面与腔四周导体壁开路构成TEM-SIW腔。相同谐振频率下,单个TEM-SIW腔的面积可以减小到传统的SIW谐振腔面积的9.5%。分析了主模式工作情况下TEM-SIW谐振腔和传统的SIW谐振腔的结构以及腔内的磁场分布。由于其磁场分布与工作在TEM模式的电容加载同轴腔相似,因此,基于这种谐振腔的滤波器可以很方便的借鉴经典的电容加载同轴腔滤波器的耦合结构和综合设计技术。最后,设计了一个基于TEM-SIW腔的三级双频滤波器,其性能已经通过了数值仿真和实验验证。     

A novel rat race coupler design for dual-band applications

This letter presents a novel and compact rat-race coupler design that can operate at two widely separated frequency bands. It is accomplished by modifying the length and impedance of the branch lines in the conventional structure, and the insertion of two additional shunt stubs. The proposed circuit also features planar structure and low insertion loss. For verification, the measured performance of a microstrip coupler operating at 900/2000MHz are shown.     

A compact digitally programmable reconfigurable filter for dual-mode BT/802.11b receivers

A new 4th-order reconfigurable (complex bandpass or normal lowpass) filter for implementing the channel select filter for dual-mode receivers adopting low-IF for Bluetooth (BT) and zero-IF for WLAN (IEEE 802.11b) is presented. It provides an alternative solution to the optimum low-power complex filter based on the current amplifier. The new filter avoids the employment of capacitor and/or resistor banks leading to an area efficient design solution while maintaining high linearity and relatively low power consumption. The center frequency in BT mode and the pole frequency in 802.11b mode are digitally tuned through programming active current division networks (CDNs). Experimental results obtained from 0.18 μm CMOS chips show that the proposed design offers improved characteristics over available solutions in terms of power consumption, spurious-free dynamic range (SFDR) and/or area. It achieves in-band SFDR of 65.3 dB for BT and 65.2 dB for 802.11b while it consumes 1.8 mW. Also, it offers image rejection of better than 59 dB.     

A compact and high performance dual-band bandpass filter based on unbalanced composite right/left-handed transmission lines for WLANs applications

In this paper, a novel compact microstrip dual-band (DB) bandpass filter with high selectivity for wireless local area networks applications is proposed. The design procedure is based on unbalanced composite right/left-handed (UCRLH) transmission lines (TLs). The DB features can be achieved by unbalancing the CRLH transmission line. The necessary conditions to obtain a discontinuous transition between the left- and right-handed bands, intended to provide UCRLLH TL, are investigated. The application of this technique to design of compact DB filters is illustrated. The structure of the proposed DB filter is implemented by a series interdigital capacitor located between two microstrip lines that shorted to the ground plane by vias. The vias with microstrip lines acting as a shunt connected inductor while the series capacitor is realized by interdigital capacitor. The design procedure based on a simple equivalent circuit is also introduced. The proposed filter has advantages such as compact size, easy fabrication, high selectivity, low insertion loss, high return loss and, design flexibility. To validate the proposed technique, the proposed DB filter has been fabricated and tested. Good agreement has been found between simulation and measurement results. The total size of the proposed UCRLH DB filter is 0.17 λ_g × 0.048 λ_g, where λ_g is the guided wavelength of the lower pass-band. The size of the proposed DB filter is more compact in comparison with known similar filters.     

Design of a compact microstrip tunable dual-band bandpass filter

A novel microstrip tunable dual-band bandpass filter with high attenuation level in the upper stopband region is presented. The proposed structure comprises of T-shaped resonators and the coupled microstrip feeding lines. To reach a compact size, the feeding lines are bended. By altering the physical lengths, the characteristics of BPF can easily tune. So, the operational frequencies of the filter can be adjusted and has been fixed to 2.1 GHz and 2.63 GHz, which are applicative for 3G and 4G systems. The insertion-losses of the first and second pass-bands are only 0.68 dB and 1.08 dB, respectively. The undesired harmonics in the upper stopband, with an excellent attenuation level of −38 dB, are rejected up to 6.65 GHz. The results exhibit high return loss of 19.3 dB and 30.7 dB in the first and second pass-bands. The proposed circuit has been fabricated and tested that the obtained results are well close to the simulations results. The total size of the designed circuit is only 16.4 × 13.4 mm².     

A novel dual-band tunable notch filter with controllable center frequencies and bandwidths

This article proposes a new dual-band tunable bandstop filter. This tunable filter is composed of two separate parts, the transmission line, and coupled stubs that each connect to three varactors. The center frequency and bandwidth in each band can be controlled individually. Moreover, the LC equivalent circuit of the proposed filter is calculated, and the results are simulated. In the proposed filter, the simulations show that the first stopband can be tuned in a frequency range from 1.2 to 1.9 GHz with 10-dB absolute bandwidth 310 ± 30 MHz, whereas the second stopband varies from 2.5 to 3.3 GHz with the 10-dB absolute bandwidth 720 ± 20 MHz. These two stopbands can also be tuned independently. Furthermore, the bandwidth of each fixed center frequency can be changed easily. The fabricated proposed filter validates the simulation results. The compact filter has an effective size of 9 × 27.5 mm².     

A novel coplanar-waveguide bandpass filter using a dual-mode square-ring resonator

A novel coplanar-waveguide (CPW) bandpass filter using a dual-mode resonator is presented in this letter. In the filter, a square-ring is used as the resonator, and a microstrip line stub attached the inner corner of the square-ring is used as the perturbation element. The square-ring and the input/output CPW are constructed on the two sides of a dielectric substrate, respectively. The filter has been investigated numerically and experimentally. Measured result shows that the filter has a minimum insertion loss of 1.2dB in its passband and an out-of-band rejection level of -45dB.     

A compact dual-band bandpass filter based on porous silicon dual-microcavity of one-dimensional photonic crystal

We demonstrate a laser-diode(LD)pumped actively Q-switched laser with Nd:Sc0.2Y0.8Si O5(Nd:SYSO)crystal for the first time.A stable actively Q-switched laser is obtained at dual wavelengths of 1 075.2 nm and 1 078.2 nm.The maximum average output power of 720 m W is obtained at the repetition rate of 15 k Hz under the pump power of8.7 W.The minimum pulse width of 58 ns is obtained at the repetition rate of 5 k Hz under the pump power of 8.7 W,corresponding to the peak power of 1.9 k W and the pulse energy of 112μJ.     

新型三角贴片加槽双模滤波器的设计

为了实现微波滤波器的小型化,文中设计了一个新型的三角贴片加槽双模滤波器。通过加槽的设计,使谐振器的工作频率进一步降低,从而实现了滤波器的小型化及低损耗;同时研究了该结构尺寸参数的变化对通带中心频率的影响。最后利用HFSS对滤波器进行了仿真,得到工作频率为2.352～45 GHz以及5.64～5.65 GHz的双通带带通滤波器。整个滤波器采用微带结构,经过仿真优化,得到的滤波器的滤波特性符合预期的要求。     

A dual-mode complex filter for GNSS receivers with frequency tuning

A fifth/seventh order dual-mode OTA-C complex filter for global navigation satellite system receivers is implemented in a 0.18 fxm CMOS process. This filter can be configured as the narrow mode of a 4.4 MHz bandwidth center at 4.1 MHz or the wide mode of a 22 MHz bandwidth center at 15.42 MHz. A fully differential OTA with source degeneration is used to provide sufficient linearity. Furthermore, a ring CCO based frequency tuning scheme is proposed to reduce frequency variation. The measured results show that in narrow-band mode the image rejection ratio (IMRR) is 35 dB, the filter dissipates 0.8 mA from the 1.8 V power supply, and the out-of-band rejection is 50 dB at 6 MHz offset. In wide-band mode, IMRR is 28 dB and the filter dissipates 3.2 mA. The frequency tuning error is less than ±2%.     

具有频率调谐的GNSS接收机双模复数滤波器

A fifth/seventh order dual-mode OTA-C complex filter for global navigation satellite system receivers is implemented in a 0.18μm CMOS process.This filter can be configured as the narrow mode of a 4.4 MHz bandwidth center at 4.1 MHz or the wide mode of a 22 MHz bandwidth center at 15.42 MHz.A fully differential OTA with source degeneration is used to provide sufficient linearity.Furthermore,a ring CCO based frequency tuning scheme is proposed to reduce frequency variation.The measured results show that in narrow-band mode the image rejection ratio（IMRR）is 35 dB,the filter dissipates 0.8 mA from the 1.8 V power supply,and the out-of-band rejection is 50 dB at 6 MHz offset.In wide-band mode,IMRR is 28 dB and the filter dissipates 3.2 mA.The frequency tuning error is less than±2%.     

A dual-mode bandpass filter with enhanced capacitive perturbation

A dual-mode ring bandpass filter with two pairs of capacitors has been designed. The capacitors are used to control the location of the even- and odd-mode frequencies independently, allowing weak coupling for narrow-band filter design with realizable capacitance values. Theoretical expressions have been derived for these frequencies. A 4% bandwidth bandpass filter centered at 1.9 GHz was designed and tested with good agreement between theoretical and measured results.     

一种RBF神经网络辅助设计的新型微带双模滤波器

通过引入弯折型马刺线,提出了一种新型微带双模滤波器。该结构降低了传统微带双模滤波器的耦合损耗,减小了滤波器尺寸,并具有良好的可调节带通特性。给出了该滤波器的模式激励与耦合工作机理的物理解释,并提出结合RBF神经网络方法,外推滤波器结构参数的设计方法。该滤波器实验结果与预测结果吻合良好。