一种基于超材料的谐波抑制天线罩

设计了一种基于超材料结构的前置谐波抑制单元天线罩,该天线罩采用多层互补型亚波长单元结构,在一个天线单元的有限尺寸范围内排列更多的周期单元,减小边缘效应的影响,天线罩总厚度小于5 mm,通过PMI泡沫与喇叭天线连接。采用激光刻蚀工艺制备了不同尺寸的两种试验件,并进行了超材料的传输系数测试以及带罩天线阵谐波抑制性能测试,结果表明,所设计的超材料谐波抑制天线罩具有带内0.3 dB 的插损,二次谐波20 dB和三次谐波30 dB的抑制能力。     

A novel microstrip lowpass filter with sharp roll-off and ultra-wide stopband using SICMRC

This paper presents a novel microstrip lowpass filter with sharp roll-off and ultra-wide stopband using stepped-impedance resonator and bended transmission line structure. The filter includes stepped-impedance prototype filter and stepped-impedance compact microstrip resonator cells that are combined in one structure. The proposed filter has good specifications such as sharp roll-off, ultra-wide stopband and low insertion loss. The transition band is approximately 0.25 GHz from 1.75 to 2 GHz with corresponding attenuation levels of ?3 and ?40 dB. The attenuation level in the stopband is better than ?20 dB that is achieved from 1.94 to 23 GHz, and the insertion loss in the passband is less than 0.4 dB. The proposed filter is fabricated and measured, and the simulation and measurement results are found to be in good agreement with each other.     

Fabrication, polarisation and wavelength insensitive optical switch/attenuator based on adiabatic mode multiplexer

Experimental results of an adiabatic mode multiplexer (AMM) based novel 2/spl times/2 optical switch/variable optical attenuator that consists of a symmetric Y-branch interferometer (mode converter) and adiabatic mode multiplexer/demultiplexer pair are presented. It is shown that both normally cross and bar designs have identical optical performance. Extinction ratio without thermal activation is wavelength independent. Over C-band the attenuation at -20 dB varies by less than 0.3 dB and polarisation dependent loss is less than 1 dB. It is proved that the mode converter plays a dominant role in polarisation state sensitivity at high attenuation values and can be optimised by varying interferometer arm length. Since an AMM-based switch does not require process optimisation steps it can be fabricated within a process optimised for other optical devices.     

Compact microstrip lowpass filter with wide stopband and sharp roll-off using tapered resonator

In this article, a novel microstrip lowpass filter (LPF) with specifications such as sharp cut-off, wide stopband, low insertion loss and high return loss using tapered resonator is presented. The LPF has cut-off frequency of 1.11 GHz, where unwanted harmonics are suppressed by novel tapered cells. The bandwidth is enhanced, and the size is reduced as compared to the conventional tapered filter. The transition band is approximately 0.29 GHz from 1.11 to 1.4 GHz with corresponding attenuation levels of –3 and –20 dB, respectively. The stopband with greater than –20 dB rejection is from 1.4 to 8.9 GHz, insertion loss in the passband is less than 0.1 dB, return loss is less than –18 dB and the overall size of the filter is 0.12 × 0.073 λ_g. The proposed filter is fabricated and measured. The simulation and measurement results are in good agreement. This LPF is designed for microwave communication applications, especially wireless video transmitters.     

Sub-THz Four-Way Waveguide Power Combiner With Low Insertion Loss

A four-way waveguide power divider has been developed in sub-THz band. The waveguide power divider was achieved with the improved H-plane T-junction structure. By tuning the depth and width at the junction of the waveguide, the input impendence was matched and the two-way output power amplitude and phase were at the same level. The four-way power divider was realized by the concatenation of two same T-junction at the two output ports. A sub-THz four-way passive power combiner is designed, fabricated and measured. The measure results show that the measured insertion loss of the fabricated four-way passive power combiner is less than 1.2 dB whereas the input return loss is greater than 14.8 dB from 97.5 to 101.7 GHz. Experiments on the sub-THz four-way passive power combiner show that a minimum insertion loss of 1 dB has been achieved at about 99.5 GHz. The measured minimum insertion loss of the waveguide power divider is half of the insertion loss for the entire passive power combiner (0.5 dB), which corresponds to a power-combining efficiency of 89 %. The measured results agree with the simulated ones closely.     

Experimental 1.5 μm coherent optical fibre transmission systems

The authors consider the design requirements for 1.52 μm coherent optical fibre transmission systems. Some of the essential requirements are: narrow linewidth sources, polarisation stable transmission media, low insertion loss optical mixers and frequency tracking or phase locked local oscillators. Having been successful in reducing the linewidth of semiconductor lasers to less than 30 kHz, by using injection locking techniques, and in fabricating optical mixers with insertion losses of the order of dB, they have been able to experiment with coherent optical fibre transmission systems to assess their practicability. In this paper it will be shown that coherent systems can be operated over long lengths of conventional low loss monomode fibre without any polarisation penalty and give far better performance than direct detection systems.     

Compact wide stopband lowpass filter using spiral loaded tapered compact microstrip resonator cell

A new spiral loaded tapered compact microstrip resonator cell (SPLT-CMRC) is presented. The addition of spiral stubs to the CMRC creates transmission zeroes in the stopband which extended the stopband of the ?lter. The proposed resonator is used to design a compact lowpass ?lter (LPF) with wide and high rejection in stopband. The fabricated ?lter has a 3 dB cutoff frequency at 8 GHz. The insertion loss in the passband is less than 0.2 dB from DC to 7.2 GHz. The proposed ?lter has wide stopband from 9.47 to 40 GHz with attenuation level of ?20 dB. The demonstrated filter is designed and fabricated. There is a good agreement between the measured and simulated S-parameters.     

Method for improving ladder bulk acoustic wave filters rejection

This paper address design guidelines for improving the rejection of ladder bulk acoustic wave filters. An overview of the bulk acoustic wave filters technology enables to outcome the principal features of ladder filters. The lack of out-of-band rejection is currently an important weakness of this topology. The design technique presented enables to improve bulk acoustic wave ladder filters rejection by using their input/output bonding wires. Finally, the technique is used for design and fabrication of a bulk acoustic wave ladder filter for application in W-CDMA reception (2.11–2.17 GHz) front-ends. The filter measurement results show a significant improvement on the filter rejection at the transmission band (from ?19 to 34 dB) and on the return loss (from ?10 to ?16 dB) without considerable modification of filter insertion loss and selectivity.     

Miniature high selectivity filters using grounded spiral resonators

A novel miniature high selectivity filter designed using a metamaterial resonator based on four grounded spirals (ForeS) is presented. This enables extreme size reduction together with high out-of-band rejection and low insertion loss. A fabricated third-order filter has overall dimensions of lg/4 by lg/15, a 3 dB bandwidth of 3.7% at 1.63 GHz, insertion loss of 23 dB, attenuation greater than 75 dB in the lower stopband and greater than 40 dB up to 2.6 times the centre frequency.     

Compact broadband planar orthomode transducer

The design and test results of a compact C-band orthomode transducer are presented. The transducer comprises four rectangular probes orthogonally arranged in a circular waveguide, designed to work in the WG13 band. Measurements of the system in the frequency range 4.64 - 7.05 GHz agree very well with simulation results and show a cross-polarisation level below -58 dB, a return loss of about -20 dB, and an insertion loss difference of less than 0.18 dB between the orthogonal polarisation modes across the full waveguide band.     

114.3~123 GHz六阶带通滤波器设计

基于经典的半波长滤波器理论,设计了一种用于太赫兹通信系统的半波长磁耦合矩形波导带通滤波器。仿真结果表明,该滤波器中心频率为118 GHz,通带为114.3~123 GHz,相对带宽为7.4%;在131.8 GHz处的抑制度大于30 dB,通带插入损耗小于0.8 dB,通带回波损耗大于20 dB。经过实物测试,测试结果与仿真结果基本一致。这种滤波器的结构简单,制作难度低。     

Compact and low-loss arrayed waveguide grating module with tolerance-relaxed spot-size converter

A compact, low-loss arrayed waveguide grating (AWG) module was achieved by adopting a novel optical spot-size converter (SSC) to planar lightwave circuits (PLCs). The SSC is a laterally tapered waveguide that can be fabricated simply by the conventional fabrication process. The structure is composed of a core width converting region where the spot-size is converted efficiently, and a core width fine-tuning region where the cut-position tolerance is relaxed. We have applied this structure to a 1.5%-/spl Delta/ silica-based waveguides and reduced the single-mode fiber coupling loss to less than 0.5 dB/point. The SSC provides a large cut-position tolerance that enables angle polishing of the PLC endfaces to prevent reflection and low-loss connection of pigtail fibers. The center channel insertion loss of the AWG module was reduced from 4.2 to 2.2 dB, and the reflection was less than -60 dB.     

高隔离度S波段MEMS膜桥开关

常规的 MEMS膜桥开关在 1 0 GHz以上频段才具有低插损、高隔离度 (>2 0 d B)的优点。文中介绍了一种应用于微波低频段—— S波段的高隔离 MEMS膜桥开关 ,给出了开关的设计与优化方法 ,建立了开关的等效电路模型。通过双膜桥结构、选择高介电常数的介质膜、微电感结构膜桥这些措施 ,达到提高开关隔离度的目的。利用 HFSS软件仿真的结果表明 ,该开关在微波低频段 (3～ 6GHz)有着很好的隔离性能。开关样品在片测试的电性能指标 :插损 <0 .3 d B,隔离度 >40 d B,驱动电压 <2 0 V     

Analysis and Design of a Novel W-band SPST Switch by Employing Full-Wave EM Simulator

In this paper, a W-band single pole single throw (SPST) switch based on a novel PIN diode model is presented. The PIN diode is modeled using a full-wave electromagnetic (EM) simulator and its parasitic parameters under both forward and reverse bias states are described by a T-network. By this approach, the measurement-based model, which is usually a must for high performance switch design, is no longer necessary. A compensation structure is optimized to obtain a high isolation of the switch. Accordingly, a W-band SPST switch is designed using a full wave EM simulator. Measurement results agree very well with simulated ones. Our measurements show that the developed switch has less than 1.5 dB insertion loss under the ??on?? state from 88 GHz to 98 GHz. Isolation greater than 30 dB over 2 GHz bandwidth and greater than 20 dB over 5 GHz bandwidth can be achieved at the center frequency of 94 GHz under the ??off?? state.     

带有交叉耦合的平行四腔螺旋滤波器设计

针对螺旋滤波器的结构及耦合方式,采用平行四腔的直线形交叉耦合结构,在非相邻的一腔和四腔间添加控制部件,从而引入传输零点以提高带外抑制.用Ansoft HFSS软件设计并制作了一款体积为150mmx60mmx70mm,中心频率为380MHz的螺旋滤波器.测试结果表明,该滤波器的带内回波损耗大于20 dB,插损小于2dB,...     

一种新型波导-基片集成波导转换器设计

本文提出了一种新型波导-基片集成波导转换器的设计方案。矩形波导中的电场通过该对极鳍线转换器后在基片集成波导中传输。该转换器的优点是：结构形式简单,长度短,带宽较宽。利用HFSS 仿真对过渡段结构进行了优化, 30G到40G 的频率范围内,插入损耗小于0.13dB,回波损耗优于20dB。背靠背插入损耗小于0.22dB,回波损耗优于20dB,相对带宽大于25%。     

A Ka-Band GaAs Monolithic Phase Shifter

The design and performance of a GaAs monolithic 1800 one-bit switched line phase shifter test circuit for Ka-band operation is presented. A self-aligned gate (SAG) fabrication technique is also described that reduces resistive parasitic in the switching FET's. Over the 27.5-30 GHz band, typical measured differential insertion phase is within 10-20° of the ideal time delay characteristic. Over the same band, the insertion loss for the SAG phase shifter is about 2.5-3 dB per bit. The SAG fabrication technique holds promise in reducing phase shifter insertion loss to about 1.5 dB/bit for 30-GHz operation.     

A Compact and Broadband Differential Microstrip Line to Rectangular Waveguide Transition Using Dipole Antenna

In this paper, a compact full Ka-band differential microstrip line (DML) to rectangular waveguide transition is proposed. The dipole antenna with semi-elliptic arms is introduced to transform the differential mode of DML to the TE10 mode of the rectangular waveguide directly. The two arms of the dipole antenna are connected together by a shorting strip to reduce the size of the dipole. Compared with the DML-to-waveguide transition using the fin-line topology, the size of the proposed transition has been reduced by 86 %. To verify this transition, a back-to-back structure is fabricated and tested. It provides a return loss of better than 15.2 dB and an insertion loss of 0.73 to 1.07 dB within a wide frequency range from 26.5 to 40 GHz. The measurement results show good agreement with the simulation results. Furthermore, a tolerance analysis is also performed via the simulation to prove that this transition is robust in the fabrication and mechanical assembly.     

Ultra-wide Bandwidth Inter-Chip Interconnects for Heterogeneous Millimeter-Wave and THz Circuits

Heterogeneous chip-to-chip interconnects with low loss and ultra-wide bandwidths have been demonstrated. Coplanar waveguide-based interconnects between GaAs and Si die have been fabricated and characterized and the results compared to expectations from full-wave electromagnetic simulation. Broadband transmission characteristics were obtained, with insertion losses below 0.3 dB at 100 GHz and below 0.8 dB at frequencies up to 220 GHz demonstrated experimentally. The measured return loss exceeded 11.5 dB at all frequencies up to 220 GHz. The interconnects offer low latency, with a measured group delay of 0.69 ps. The measured results are in good agreement with full-wave simulations, indicating that the measured results do not suffer from significant impairments compared to theoretical predictions. The demonstrated interconnects offer an alternative to conventional approaches to millimeter-wave circuit and system integration, by enabling the compact realization of circuits in the microwave, millimeter-wave, sub-millimeter-wave, and THz frequency regimes in heterogeneous device technologies with very low chip-to-chip insertion loss.     

一种基于介质谐振器的新型电磁超材料

文章设计了一种基于介质谐振器的新型混合左右手结构。该结构由工作在横电模式TE的介质谐振器嵌入到平行平板波导中组成。数值分析表明：工作频带为12 GHz～14 GHz,在13.15 GHz频率下相移为零。该结构在整个通带内插入损耗低于0.6 dB,同时具有极低的通带波纹,表现出了良好的传输特性。与普通的混合左右手结构相比,其结构简单,插入损耗较低,在高频时导体损耗也较低,在超级透镜、天线等领域具有很好的应用前景。