A Unified Approach to the Analysis of a Category of H-Plane Discontinuities

Based on the mode matching method, the generalized scattering parameters including the fundamental and higher order modes (multi-modes) are obtained for the discontinuity interface of a category of waveguide H-plane discontinuities. Then by using a general port-connection order-decrease method raised by the author, the whole discontinuity including the two interfaces and the intermediate part of finite length or zero length (as is the case for very thin inductive windows or irises) can be combined into one network, and the generalized scattering parameters of this network can be obtained from which the scattering parameters of the fundamental mode can be extracted. If needed, the equivalent circuit parameters can be calculated directly from the scattering parameters. Examples are given to show the validity and versatility of this new method for dielectric filled waveguide, inductive iris and/or window, E-plane metal and/or finline insert, and even the offset E-plane finline insert, etc.. Multiple inserts, windows and irises can also be analysed.     

A nanometric plasmonic waveguide filter based on Fabry-Perot resonator

A compact nanometric surface plasmon polariton Fabry-Perot filter based on three metal-insulator-metal (MIM) waveguides is proposed and studied. The characteristics of this SPP band pass filter are analyzed by the finite difference time domain method and the Fabry-Perot resonance model. The results show that the resonance wavelengths of the pass bands can be linearly changed by the resonant cavity length, and the transmission ratios of the pass bands can be varied by altering the gaps between the MIM waveguides. The metal loss and dispersion effects on the SPP filter's spectra are considered as well. This kind of simple filter is very promising for high density SPP waveguide integrations.     

Ka波段8路径向波导空间功率分配(合成)器

通过理论研究以及高频仿真相结合的方法分析设计了一款新型Ka波段8路径向波导空间功率分配(合成)器。研发的新结构输入输出段为标准矩形波导结构,代替了传统功率分配(合成)器输入输出段的同轴结构,这种新型全金属结构更加简单紧凑,更易于加工。仿真结果表明:功率分配(合成)器工作带宽达到了34%(12GHz),基本覆盖整个Ka波段;全频带内反射系数S11低于-20dB,各支路的相位差均小于5°。通过在同轴波导渐变段引入切比雪夫渐变结构,在减小了器件尺寸的同时,在整个频带内的网络S参数也不错。这款新型Ka波段8路径向波导功率分配(合成)器将应用于前级固态功率放大器,推动回旋行波管项目研发。     

微波频段表面等离子激元波导滤波器的实验研究

基于理论分析, 实验研究了二维磁单负材料/双正材料/磁单负材料表面等离子波导的滤波效应. 研究表明, 该波导结构具有低通滤波性质, 引入分支缺陷之后, 由于谐振效应该波导具有带阻滤波效应. 分支缺陷相当于亚波长谐振腔, 谐振腔的长度决定带阻滤波器的中心频率, 而中心频率几乎不受缺陷位置的影响; 滤波器透射率下降的幅度由耦合距离决定. 通过引入谐振腔及改变谐振腔的长度、数量以及耦合间距等参数, 可以实现可调节的表面等离子波导滤波器. 实验结果与理论分析符合得很好, 该性质将在可调的单通道或多通道带阻滤波器件中具有潜在的应用价值. 关键词： 表面等离子激元 特异材料波导 谐振腔 滤波器     

Multilayer resonances sharpened by grating waveguide resonance

A multilayer planar structure comprising a highly reflective multilayer dielectric mirror and a corrugated waveguide is proposed for use as a narrow passband optical filter. The proposed filter has a much narrower linewidth than a usual Fabry–Perot cavity with two multilayer dielectric mirrors. It is shown that the narrowing of the linewidth is due to the strong spectral dependence of the phase of the wave reflected from the waveguide grating mirror. The shape of the pass band can be made symmetrical by a proper choice of the grating groove profile.     

多注速调管π模双间隙腔截止波导输出回路研究

 用数值模拟的方法研究了多注速调管π模双间隙腔加载截止波导两节滤波器型输出回路的特性，并重点研究了π模双间隙腔与截止段的耦合结构对输出腔间隙阻抗频率特性的影响，以及耦合接头和电容性销钉对截止波导滤波器的调谐作用。研究结果表明：π模双间隙腔连接截止波导段的耦合口的尺寸主要影响输出腔的外观品质因数，而耦合接头的粗细和电容性销钉的大小和插入深度对截止波导滤波器的调谐具有重要影响。另外，由于耦合接头相当于在截止段中引入了一个附加电感，这使滤波器谐振电路的品质因数变大，谐振峰变窄。因此，π模双间隙腔加载截止波导滤波器型输出回路并不比单间隙腔加载截止波导滤波器型输出回路有更好的带宽优势。     

基于波导口的新型Ka频段超导滤波器设计

传统的Ka频段高温超导滤波器设计都是基于同轴接口．本文首次提出了一种新型的波导接口的Ka频段高温超导滤波器,滤波器与波导微带转换集成设计．设计中利用参数扫描技术克服了由于介质非均匀性而引起的频率偏移问题．测试结果表明本文提出的方案可以显著改善滤波器的性能．相对传统的基于同轴接口的设计方案,本文提出的方案可以显著改善滤波...     

Electrodynamic Analysis and Synthesis of an Elliptic Filter Based on Complex Resonant Irises in a Rectangular Waveguide

Radiophysics and Quantum Electronics - We have synthesized elliptic bandpass waveguide filters. The resonators of the filter are thin plane-transverse resonant irises with an aperture in the form...     

Ka波段波导滤波器的设计

采用高精度三维电磁场分析软件对电感膜片建模,并与等效电路相结合设计波导带通滤波器。实验结果表明,样品测试结果与仿真结果基本吻合,该方法不仅适合波导滤波器设计,也适合其它谐振器耦合结构滤波器的设计。     

高功率TE_(01)过模斜接弯头设计

设计并分析了TE01斜接弯头结构,该结构由两段相同且垂直的模式变换段及与模式变换段呈45°斜接的金属镜面组成。整个结构等效于两个模式变换段对接,但中间存在间距为波导直径的缝隙。模式变换段将纯TE01模式转换为TE01和TE02的混合模式,该混合模式在缝隙中传播时电场呈现对称分布,从而降低了模式转换损耗,提高了传输效率。对设计的Ka波段TE01斜接弯头结构的理论仿真和加工实测结果表明:中心频点转换效率在98%以上,在2 GHz带宽内传输效率95%以上,插损小于0.2 dB,驻波小于1.2。     

Effects of metal irises on the guided-mode properties in asymmetrical slab waveguides

The diffraction phenomenon caused by metal transverse irises placed into an asymmetrical slab waveguide is examined by using the integral equation method. We concentrate on the possibility of controlling the radiation characteristics of the structure by changing the irises positions and the slab waveguide asymmetry. The aperture electric-field distribution is expressed in terms of a finite series of Chebyshev polynomials. The dominant TE guided-mode reflection and transmission coefficients, the near-field distribution and the far-field radiation pattern are calculated, while numerical results are presented for several cases of asymmetrical slab waveguides and different irises’ positions.     

Study on the Characteristics of the Rib-Loaded Disk-Loaded Waveguide

The disk-loaded waveguide with bandwidth of only 2%-8% is a kind of narrow band structure. A new rib-loaded disk-loaded waveguide with wider bandwidth than the general one is suggested in the paper. The author develops the method of calculating the axial periodic waveguide by expanding the slow-wave structure's boundary function in Fourier series, so that it can be adopted in rib-loaded disk-loaded waveguide. By the method, the dispersion characteristics and interaction impedance of a Ka band rib-loaded disk-loaded waveguide are analyzed.     

基于电磁带隙结构的新型高温超导低通滤波器

提出了一种基于电磁带隙结构的低通滤波器实现形式,这种新型低通滤波器采用电容周期性加载共面(Coplanar Waveguide)传输线结构的形式.为了减小通带内波纹、显著提高阻带信号抑制,电容单周期性加载结构被调整为电容双周期性加载结构,同时在共面传输线的接地面上引入了双周期性的长方形缺陷地结构.基于上述方案设计制作了一个高温超导低通滤波器,仿真及测试结果表明:低通滤波器的带外抑制平均增加了约20 dB,带内传输损耗波纹显著变小.     

A rigorous cad of millimeter wave bandpass filter with all-metal insert in waveguide

In this paper, a bandpass filter with all-metal insert, an inductive strip in the E-plane of a waveguide is analyzed by a prototype filter and the scattering matrix of the strip is calculated by electromagnetic fields theory theoretically. By means of matrix combining technique, the scattering matrix of a bandpass filter of this type is obtained. And a rigourous error function is used to optimize the CAD program by Powell's method and make the experimental results agree well with the theory design at V-band.     

Corrugated waveguide band edge filters for CMB experiments in the far infrared

Millimetre wave corrugated waveguide-horn structures are used as both single-moded and multi-moded bolometer feeds in a number of cosmic microwave background (CMB) experiments (e.g. PLANCK, Archeops, QUaD). Such horns tend to be employed over a relatively wide bandwidth and for single-moded horns the waveguide acts as the high pass filter. In this paper we report on our investigation on how the waveguide details determine the exact location of the low frequency band edge of such corrugated horns. A sharp step-like band edge, below which there is negligible propagation, is ideally required. Furthermore any leakage below the expected cut-off, possible in corrugated guides, could lead to non-idealised cross-polar effects. Typically deeper corrugations are required in the waveguide filter than at the horn aperture for wide bandwidth operation, thus necessitating a transition section over which the corrugation depth smoothly varies. An electromagnetic mode matching technique and a surface impedance hybrid mode model are used to compute the horn transmission characteristics. We have also undertaken laboratory measurements of the band edge of prototype corrugated horns in order to test the models.     

Analysis and design of a new type NRD-guide E-plane Y-junction circulator

A new type of E-plane Y-junction circulator has been developed based on the nonradiative dielectric waveguide (NRD-guide) in Ka- band. First, the circulation principle has been analysed by the theory of polarization wave. The field components in the nonreciprocal Y-junction zone and the conclusion of 60° phase difference between clockwise and counterclockwise rotating polarization modes has been obtained. And then, the resonant frequency of the non-dc biased triangle ferrite sample has also been calculated. This kind of structure is benefit to enlarge the bandwidth of the Y-junction circulator. As an example, we had designed and fabricated a circulator in Ka-band. Its operating frequency is 35. 1GHz, the 1.5dB insertion loss and 20dB isolation bandwidth is about 1. 0GHz.     

Corrugated waveguide band edge filters for CMB experiments in the far infrared

Millimetre wave corrugated waveguide-horn structures are used as both single-moded and multi-moded bolometer feeds in a number of cosmic microwave background (CMB) experiments (e.g. PLANCK, Archeops, QUaD). Such horns tend to be employed over a relatively wide bandwidth and for single-moded horns the waveguide acts as the high pass filter. In this paper we report on our investigation on how the waveguide details determine the exact location of the low frequency band edge of such corrugated horns. A sharp step-like band edge, below which there is negligible propagation, is ideally required. Furthermore any leakage below the expected cut-off, possible in corrugated guides, could lead to non-idealised cross-polar effects. Typically deeper corrugations are required in the waveguide filter than at the horn aperture for wide bandwidth operation, thus necessitating a transition section over which the corrugation depth smoothly varies. An electromagnetic mode matching technique and a surface impedance hybrid mode model are used to compute the horn transmission characteristics. We have also undertaken laboratory measurements of the band edge of prototype corrugated horns in order to test the models.     

缺陷态同轴布拉格波导传输特性

采用基于Ansoft HFSS的电磁仿真平台,研究了一个工作于Ka波段（37.5 GHz附近）的缺陷态同轴布拉格波导在不同的开槽方式及缺陷位置条件下的传输特性。结果表明:该波导只有在内外导体壁单面开槽并引入缺陷,或者双面开槽且两个开槽面同时引入缺陷的条件下才能够有效地产生出传输通带;对于后者而言,将内外导体壁的波纹初始相位差设置为且让缺陷位于波导中间时,可以获得带宽极窄、阻带抑制范围较宽的传输通带,此时,给内外导体壁的缺陷引入适度的错位能够对通带的中心频率、带宽等性能指标起到微调作用,而引入大间距的错位则能够在禁带中产生出多个通带,从而起到多通道滤波的作用。     

Optimized 90° Polarization Shift Step Twists for Ku, K and Ka Bands

Optimized models for 90° polarization shift step twists for Ku, K and Ka bands are presented. The cross-section of the waveguide employed is similar to that of a rectangular one, with the difference that the walls of the shorter side are part of a circular one with the proper diameter. The optimized models have been found using the CST Microwave Studio simulation tool and in all cases the return loss is kept below -20 dB for a wide range of frequency spectrum. Two examples are given, one for Ku band and the other for K and Ka ones.     

AN ACOUSTIC DECAY MEASUREMENT BASED ON TIME-FREQUENCY ANALYSIS USING WAVELET TRANSFORM

In acoustic decay measurement using the third-octave band pass filter, it is known that an inevitable experimental error is produced by “ringing” at the tail part of the impulse response of the third-octave band pass filter. This ringing gives rise to distortion of the decay curve. In order to reduce this error and to obtain an acceptable acoustic decay curve, it has been recommended that the product of the 3 dB bandwidth B of the third-octave band pass filter and the reverberation time T₆₀ of the room under test be at least 16. For a listening room having short reverberation time and at the low-frequency band with narrow bandwidth, the decay curve cannot, therefore, be measured reliably by using the third-octave band pass filter. In this paper, the continuous wavelet transform (CWT) has been proposed to determine accurately the decay curve with a low value of BT₆₀. The CWT decomposes an acoustic decay signal into time-frequency domain using the third-octave band wavelet filter bank. When the CWT is applied to the measurement of an acoustic decay curve, it is found that the requirement BT₆₀>16 can be replaced by the replacementBT₆₀ >4.