SIW窄带带阻滤波器的设计和仿真研究

基片集成波导(Substrate Integrated Waveguide—SIW)是一种新型的高品质因数、低损耗集成波导结构,易于设计和加工,可以广泛应用于微波毫米波集成电路中。由于和传统矩形波导的相似性,很多设计概念可以借用,比如波导功分器、滤波器、天线等,利用该结构设计出一种带阻滤波器,其中心频率为4.85GHz,相对带宽为1.2%,最大衰减为48dB。该滤波器具有体积小,容易加工和集成等优点。     

一种基于SIFW的小型化宽带带通滤波器

为实现射频系统的小型化,本文设计出一种基于基片集成折叠波导( Substrate integrated folded waveguide,简称SIFW)的小型化宽带带通滤波器,并给出了仿真结果.为了改善带外抑制,滤波器通过交叉耦合,在通带低端引入两个传输零点.为改善通带高端滤波特性,在顶层和底层金属微带上刻蚀互补型开口谐振环(Complementary Split Ring Resonators,简称CSRR).仿真结果表明,所实现的滤波器中心频率在7.1 GHz,相对带宽约为47％,通带内回波损耗优于-15dB,插入损耗小于0.7dB.     

一种小型化微波宽带带通滤波器及其工程设计分析

在无线通信系统高速发展过程中,微波滤波器有着较为重要的价值与作用。微分电路可以有效解决环境噪声以及电磁干扰抑制性问题,微波差分滤波器是现阶段研究的重点。基片集成波导具有较高的速度,加工也较为便捷,具有较大功率容量的优势,在滤波器设计中应用相对较为广泛。SIW在差分滤波器的设计中应用效果更为显著。基于此,文章主要对一种小型化微波宽带带通滤波器及其工程设计分进行了简单的分析。     

玻璃基掩埋式光波导堆栈的制作与表征

在硅酸盐光学玻璃基片上制作了光波导堆栈, 这种光波导堆栈通过Ag⁺/Na⁺熔盐离子交换和电场辅助离子扩散技术顺次制作了两层掩埋式光波导. 对光波导堆栈的横截面显微结构进行了观察, 并对堆栈中两层波导的损耗特性进行了测试. 所获得的光波导堆栈中的上、下两层波导芯部分别位于玻璃表面以下14和35 μm处; 上层光波导芯部尺寸约为12 μm×7 μm; 下层光波导芯部尺寸约为9 μm×8 μm. 通光测试显示两层波导在1.55 μm工作波长下均为单模光波导, 且两者之间没有相互耦合. 损耗测试分析结果显示: 堆栈中两层光波导的传输损耗均约为0.12 dB/cm,与单模光纤之间的耦合损耗分别为0.78和0.73 dB. 分析表明, 这种光波导堆栈在玻璃基集成光芯片的高密度集成方面具有很好的应用前景.     

基于CRLH-TL零阶谐振特性的新型串联功分器

 结构紧凑的功分器是微波信号分离、阵列天线馈电等应用场合的重要器件．利用混合右/左手传输线（CRLH-TL）来设计小尺寸的串联功分器,并对混合右/左手传输线的色散特性进行理论分析．利用贴片电容和微带线电感设计了一种新的混合右/左手传输线,处于零阶谐振状态的混合右/左手不引入相位偏移且波长为无穷大．基于CRLH-TL的零阶谐振特性设计制作了一个工作在2.45 GHz的4路微波功分器．此功分器等幅同相地将输入功率分配到各个输出端口,输出端口位置对功率分配没有影响．使用矢量网络分析仪对该功分器进行了实验测量,结果表明：在2.20~2.65 GHz的频率范围内,功分器各输出端口功率相差在1 dB内;在2.22~2.56 GHz的频率范围内,输出端口的相位差在15°以内．测量结果与仿真结果吻合良好．该微波功分器结构紧凑,可扩展到任意多个输出端口．     

新型半模基片集成波导漏波天线

 为了设计一种结构简单、可靠性高的全向天线,提出了一种基于半模基片集成波导技术的漏波天线.这种天线是在半模基片集成波导结构的H壁增加4个对称振子形成的漏波辐射结构.使用电磁仿真软件对提出的天线结构进行了精确的建模,分析了介质厚度对天线带宽的影响,并对天线结构进行了优化,最后制作了天线测试样片进行实验验证.所设计的天线具有较宽的带宽和准全向辐射的特性,在7.3~9.7 GHz频段内具有良好的辐射性能,最大增益为5.8 dBi,测试结果验证了设计的有效性．     

基片集成波导技术的研究现状和展望

综述了基片集成波导(SIW)技术研究的现状和热点,首先分析了SIW的基本理论,包括SIW结构设计、损耗机制和频带宽度等;然后详细分析了基于SIW的微波和毫米波器件,包括无源器件、有源器件、天线和可调谐器件;接着对基于SIW技术的器件模拟和制作进行了详细论述;最后对SIW技术应用于太赫兹器件的设计进行了展望.     

一种双脊波导到同轴转换器的设计与实现

双脊波导相对矩形波导具有更宽的单模工作带宽,而一个微波系统中各类传输线之间的转换器也是必不可少的。介绍一种双脊波导(WRD650—工作频段6.5GHz～18GHz)到同轴N型接头的转换器的设计与实现。采用HFSS高频仿真软件进行设计和仿真,优化后的最大驻波比小于1.25、插入损耗低于0.06dB;其实测结果分别为1.3和0.2dB。该转换器具有频带宽、驻波低、插损小等优点。     

人工表面等离子体的电容耦合带通滤波器

设计了基于人工表面等离子体激元(spoof surface plasmonpolaritions,spoof SPPs)的电容耦合带通滤波器.该滤波器由刻蚀有菱形孔的金属结构单元以一定的间距周期性的排列在传输方向上构成耦合结构,同时设计一种特殊的过渡结构用来有效地匹配人工表面等离子体激元波导能量传输.从色散关系可以看出菱形孔结构支持人工表面等离子体激元模式.仿真结果表明,该滤波器3dB带宽为11.6GHz到18.3GHz.该滤波器结构紧凑、简单、易集成,能在将来发展的微波等离子体集成电路与系统中扮演重要的角色.     

基于EBG结构的基片集成波导超宽带带通滤波器

为拓展带通滤波器的通带带宽,设计了一种基于EBG结构的基片集成波导（SIW）超宽带带通滤波器．该滤波器利用箭头形电磁带隙结构的阻波特性,将不同大小箭头形结构单元蚀刻在SIW上金属面,以获得超宽带通带．所设计的滤波器中心频率在985 GHz,相对带宽为3959%,通带内的最大插入损耗约为154 dB,相比于类似结构的带通滤波器,其带内回波损耗较大,且整体电路面积较小．测量结果与仿真结果基本吻合,有效地验证了该设计方法的有效性．     

Design and implementation of low sidelobe substrate integrated waveguide longitudinal slot array antennas

Low sidelobe longitudinal slot array antennas are investigated based on substrate integrated waveguide (SIW) technology. The design method consists of the characterisation of the radiating element, the synthesis of the linear array and the development of the planar array including a feeding power divider by performing fullwave electromagnetic simulations for the final accurate design. Two planar slot array antennas are fabricated with a normal printed circuit board (PCB) process. Low sidelobe features are verified by the measured results which are in agreement with the simulated results. For an 8 x 8 SIW slot array antenna, the measured sidelobe levels (SLLs) are below 236 dB in the H-plane and below 225 dB in the E-plane with the Gain of 20.3 dB at 9.9 GHz. And for a 16 x 16 antenna, the SLLs are below 230 dB both in the E-plane and H-plane with the Gain of 24.4 dB at 10 GHz. The achieved design goals on the radiation patterns therefore validate the proposed low sidelobe SIW slot array antennas to be valuable candidates for high performance communication and radar applications.     

Integrated sub-harmonically pumped up-converter antenna for spatial power combining

A Ka-band sub-harmonically pumped up-converter antenna employing the substrate integrated waveguide (SIW) technique is proposed and used to realise a low-cost transmitter together with spatial power combining architecture in this paper. A single Ka-band sub-harmonically pumped up-converter using SIW band-pass filter is developed, exhibiting a conversion loss of about 7 dB. Based on the designed up-converter and SIW feeding antipodal linearly tapered slot antenna (SIW-ALTSA), the integrated up-converter antenna is designed and fabricated. Measured results of equivalent isotropic radiated power (EIRP) and radiation patterns are given. Finally, a 2 x 2 up-converter antenna array is designed and fabricated. Measured result shows the array has a power combining efficiency of above 90% and IM3 EIRP of 16 dBm. In close-range point-to-point communication and radar systems, the demonstrated millimetre-wave sub-harmonically pumped up-converter antenna array can be considered as a transmitter because of its low cost, high dynamic range and high linearity.     

Investigation of a power divider using a coaxial probe array in a coaxial waveguide

A novel coaxial-waveguide power divider using coaxial probe array that achieved low-loss probe-to-waveguide transitions is presented. The small reflection theory of transverse electomagnetic (TEM) lines is extended to synthesise the gradual waveguide taper, and the equivalent-circuit approach is applied to analyse the coaxial probe array. The design and simulation of a single probe-to-waveguide transition have been developed. The detailed design, simulation, fabrication and measurements of a four-way coaxial power divider are discussed. The measured results agree well with the simulated results. The measured 15 dB return loss bandwidth of this waveguide power divider is demonstrated to be 8.2 GHz (fL = 7.8 GHz, fH = 16 GHz) and its 0.5 dB insertion loss bandwidth 11 GHz.     

Efficient and accurate design of substrate-integrated waveguide circuits synthesised with metallic via-slot arrays

A new class of substrate-integrated waveguides (SIWs) is proposed, which highlights a novel synthesis of waveguide circuits using metallic via-slot arrays instead of via-hole arrays. When the gaps between the slots are small enough, the broadside dimension of equivalent rectangular waveguide is approximately equal to the spacing between the inner walls of slots. Therefore the size of the SIW can directly be used to calculate propagation constants almost without phase bias. This new design is of critical importance in the design of substrate-integrated circuits (SICs) with fine and sensitive geometrical details with respect to circuit response such as filters and resonators. In this way, the design of SICs based on the new SIW structures can greatly be simplified. A finite difference frequency-domain method accelerated by an implicitly restarted Arnoldi method is developed to model the substrate-integrated resonant cavities with leakage. Simulated and measured results have confirmed the fact that conventional waveguide components are very similar to the SIW counterparts of the same structure.     

Passive planar multibranch optical power divider: some design considerations

Design analysis has been performed on a passive planar multibranch waveguide optical power divider in a z-cut LiNbO3 substrate. Specifically, 5- and 3-branch waveguide structures were investigated with the effective index and field matching methods, taking into account the phase changes in the branches at the branching interface. Conditions for equal power division were examined regarding the appropriate branching angle and the relative index distribution in the branches. Illustrative numerical examples are presented and discussed.     

Analytical equivalence between substrate-integrated waveguide and rectangular waveguide

Rectangular waveguide (RW) with sidewalls of vertical conducting cylinders (i.e. SIW, substrate-integrated waveguide) becomes popular with the advent of low-temperature co-fired ceramic structure; its analysis is usually numerical, or modal, leading to empirical design formulas. However, its analytical equivalence to the common RW of the solidwall is identified; in other words, analytical design formulas of the SIW and the equivalent RW of solid sidewalls are the same. The equivalence is established on comparing the surface impedances along the side walls, of the SIW and of an RW through analytical continuation. The equivalence formulas, propagation and cut off frequency show very good agreement with the results from both numerical simulations and measurements of hardware experiments, and over wide frequencies. The good agreements are easily understood on the basis of the conformal maps and the variational principle.     

Short-circuit equivalence between rectangular waveguides of regular sidewalls (rectangular waveguide) and sidewalls of cylinders (substrate-integrated rectangular waveguides), plus its extension to cavity

Substrate-integrated rectangular waveguide (SIW) is a rectangular waveguide (RW) with two sidewalls of cylinders (vias) instead of solid walls connecting the solid wall of the top and bottom plates. An equivalence formula between their widths has been derived based on the work by Che et al., 2005 [2005 Asia-Pacific Microwave Conference, Suzhou, China, December 4-7, 2005, pp. 296-299]. The authors have derived the equivalence formula between the locations of the corresponding short circuits by cylinder walls and by the solid wall. An extension of latter is the equivalence between resonance cavities of SIW and RW. Such equivalences are convenient for the design of small waveguides, of millimeter wave, in a multilayer circuit structure, such as the low-temperature co-fired ceramic. Some numerical simulations and experiments have been carried out to demonstrate the validity of the proposed approaches     

Theoretical and Experimental Investigation of the Tunable Y-Type Waveguide Standard Mismatch

Results of theoretical and first experimental investigations of a new device for the realization of variable standard values of the voltage standing-wave ratio (VSWR) are presented. The results show that the device, which consists of a Y-type waveguide power divider, an adjustable sliding short-circuit, and a matched load, can be used as a standard mismatch generating arbitrary values of the VSWR from 2 to 10 with small uncertainties.     

Dualband frequency-selective surfaces using substrate-integrated waveguide technology

This paper proposes a dualband frequency-selective surface (FSS) based on substrate-integrated waveguide (SIW) technology. This novel dualband FSS is constructed using double square loop slots (DSLSs) and an SIW cavity. Its frequency performance is investigated by numerical simulation using the finite difference frequency domain (FDFD) method. Another dualband FSS, constructed using convoluted double square loop slots (CDSLSs) and an SIW cavity is also investigated in order to get close passband spacing. Simulation results show that these dualband FSSs have the advantages of higher selectivity and passband insensitivity to the incident angles and polarisations, compared with conventional multiband FSSs. Experiments are carried out to verify the simulated results, and the measured results show a promising performance of the proposed FSS