波导阻抗带宽与缝隙导纳关系研究

本文从谐振阵等效网络出发,探索了缝隙波导谐振阵实现理想阻抗匹配的导纳特性,为波导谐振阵的超宽带设计提供了新思路.改进了波导并联缝隙的等效电路,首次实现缝隙导纳特性的单参数表征,创新提出了不同单元间距与单元数缝隙波导阵实现最大带宽的导纳特性分析方法,为波导缝隙阵带宽的优化设计提供了理论依据,建立了传统谐振阵非过载时的最大...     

X 波段加膜片式单脊波导裂缝天线的研究

等效导纳值是波导宽边纵缝天线的关键设计参数。为克服传统波导裂缝天线副瓣偏高、设计效率低下等问题,本文提出了一种单脊波导裂缝天线的改进设计方法,在传统波导裂缝阵列天线设计的基础上,利用等效导纳值对天线等效电路的影响,在裂缝单元下增加金属膜片,通过改变金属膜片的高度,优化裂缝等效导纳值,使得每个裂缝口径场分布更加接近于理论设计值,并在设计过程中使用牛顿迭代法提取导纳进一步缩短设计时间。通过设计实例表明:应用此方法设计单脊波导裂缝天线能够有效抑制副瓣电平,天线方位面副瓣电平可达到-30 dB 以下;在满足主要指标要求的前提下,设计效率显著提升。     

Equivalent circuit model for a waveguide probe with application to DRA excitation

A simple equivalent circuit is used to model an arbitrarily loaded waveguide probe with emphasis on probe-excited dielectric resonator antennas. The values of the lumped inductance and capacitance are obtained via the method of moments analysis for the problem of a short-circuited probe acting as a waveguide scatterer. For problems involving the excitation of an external load, the aperture through which the probe extends to the load is modeled by a shunt capacitance, and an additional transformer is introduced to model the coupling to the load. Expressions for these circuit parameters are obtained using curve-fitting techniques and are employed to determine the lengths and positions of an array of waveguide probes used to feed external loads with feeding currents of desired relative values. The procedure is applied to synthesize waveguide-fed antenna arrays to achieve a specified radiation pattern. The scanning capabilities and the effect of the mutual coupling are studied by comparing radiation patterns obtained from the analysis of the whole array and from the pattern multiplication principle.     

Increased-bandwidth resonant slot array with bidirectional radiation pattern

A resonant slot array with a bidirectional radiation pattern and an impedance bandwidth of more that 15% has been realized by measuring the admittance of a couple of longitudinal shunt slots on the opposite walls of the waveguide, and then optimizing the reflection coefficient of the equivalent network of the array in the desired frequency range.     

Multimode Equivalent Networks for the Design and Analysis of Frequency Selective Surfaces

A modular technique originally proposed for waveguide junctions, the multimode equivalent network approach based on the integral equation formulation (IEMEN), is extended to the analysis of multilayer frequency selective surfaces integrated with waveguide array antennas. This technique represents each layer and transition between layers in terms of a generalized impedance or admittance matrix, obtained directly from the solution of an integral equation with reduced kernel. Thanks to the adopted formulation, the integral equation needs to be solved only in a limited set of frequency points. The IEMEN method is validated by comparison with results available in literature.     

波导缝隙谐振阵带宽与缝隙特性关系研究

该文结合波导缝隙天线等效电路和辐射缝隙导纳特性,分析了并联辐射缝特性对波导谐振阵方向图带宽的影响,推导出天线方向图理想带宽所需要的缝隙特性.该结果为展宽谐振阵带宽提供了一种思路,为宽带波导谐振阵的设计提供有益参考.     

Modal analysis of periodic planar phased arrays of apertures

A general method is established for the evaluation of the driving point admittance of a radiating aperture, fed by a waveguide of the same cross section as the aperture, in an infinite periodic planar phased array. The array may have an arbitrary element lattice and it may be covered by a dielectric layer. The coefficients of the waveguide modal expansion and of the Floquet series representing the electromagnetic field in the waveguide and in the radiation half-space, respectively, are determined by approximately enforcing the boundary conditions in the array plane through an application of Galerkin's method. By eliminating from the set of equations thus obtained the complex amplitudes of the waveguide modes and of the Floquet harmonics, the driving point admittance can be expressed as the ratio of two determinants of order N and N-1 (N being the number of the waveguide modes utilized), whose elements contain truncated bidimensional series, structurally similar to the well-known grating-lobe series. The expression allows relatively simple numerical computations if the Fourier transforms of the waveguide vector mode functions are known in closed form (as they are for rectangular or circular elements). The variation of the power reflection loss with scan angle has been numerically calculated for various array configurations. The results are in some cases substantially different from those predicted through the conventional grating-lobe series technique, which is based on the assumption of one-mode elements.     

非线性平板介质波导传输特性的网络分析

本文提出了分析包含非线性介质的层状介质波导特性的等效传输线方法。通过把线性和非线性介质分别用等效传输线表示,从而把非线性介质这一复杂的电磁场问题等价成一个电路问题求解。其本征方程可以利用横向谐振原理得到。本文最后分析了层状介质波导包含饱和和非饱和非线性介质时TE模的传播功率与归一化传播常数之间的关系。所获得的结果与有关文献符合得相当好。     

Radiation of Millimeter Waves from a Leaky Dielectric Waveguide with a Light-Induced Grating Layer

A theoretical analysis is presented for the radiation characteristics of millimeter waves in a periodic dielectric waveguide having a light-induced grating layer. The waveguide is assumed to be composed of an insulator (sapphire) slab whose one surface is coated with a high-resistivity semiconductor (silicon) film. A boundary-integral-equation formulation is employed to obtain characteristic solutions of the waveguide. Numerical calculations are made at 94 GHz for both TM and TE polarizations. Estimations of the illumination power required to produce the grating are given. The waveguide presented in this paper, in conjunction with a high-power semiconductor diode laser array as a light source, may be developed to operate as an electronically beam-steerable leaky-wave antenna at millimeter-wave frequencies.     

Ka-band Dielectric Waveguide Antenna Array for Millimeter Wave Active Imaging System

Ka-band compact dielectric waveguide antenna array for active imaging system is given. Antenna array with WR28 metal waveguide direct feeding is specially designed with small size, high gain, good radiation pattern, easy realization, low insertion loss and low mutual coupling. One practical antenna array for 3-D active imaging system is shown with theoretic analysis and experimental results. The mutual coupling of transmitting and receiving units is less than -30dB, the gain from 26.5GHz to 40GHz is (12-16) dB. The results in this paper provide guidelines for the designing of millimeter wave dielectric waveguide antenna array.     

多端口耦合问题的等效导纳矩阵

本文提出了一种处理多端口耦合问题的有效方法。在该问题中,各端口波导分别通过一耦合孔与耦合区进行耦合。利用矩量法,首先导出了多端口耦合问题的关于传输模和截止模的等效导纳矩阵的计算公式。在此基础上,考虑到截止模加载于端口波导的特性阻抗,经过适当的矩阵运算,得到仅仅关于传输模的等效导纳矩阵。用此方法计算了一个 H 面 T 形接头的等效导纳矩阵和等效电路参数,所得结果与文献[1]们的结果非要吻合。     

基于HFSS的波导裂缝有源导纳的计算方法

提出一种基于商业软件HFSS仿真得到的开缝波导散射参数来提取辐射缝隙自导纳和有源导纳的方法。根据传输线理论．给出了通过散射参数计算孤立缝隙自导纳的公式．同时给出了考虑互耦的有源导纳方程．利用牛顿迭代法求解此方程得到裂缝的有源导纳值。该方法非常适合于波导天线阵的设计．有效地提高了天线阵的设计效率.     

Mutual coupling between slots printed at the back of ellipticaldielectric lenses

This paper presents calculations of the mutual admittance between two slots on a ground plane that are the primary feed of an elliptical dielectric lens antenna. This admittance may also be regarded as the basic constituent of a Galerkin method of moments formulation for the analysis of more complex feeding arrangements of slot antennas and coplanar waveguide circuits, it is found that the contribution of the reflection mechanisms inside the lens significantly affects the mutual admittance especially for H-plane coupling     

On the equivalent circuit representation of the slittedparallel-plate waveguide filled with a dielectric

An investigation of the equivalent π circuit representation for the transverse slit in the wall of a transverse electromagnetic (TEM) parallel-plate waveguide is presented. For the narrow slit, approximate analytic expressions for the equivalent circuit parameters are given in terms of the centerline representation and, for the arbitrarily width slit, the equivalent circuit parameters are considered by the method of moments in terms of both the centerline representation and edge representation, and various characteristics of the equivalent π admittance circuit representation are discussed. A critical look is taken at the validity of the previous model of th E-plane gap coupling between two rectangular microstrip patch antennas, and the improved model is considered for the narrow slit (gap) width case     

Input Admittance of a Circular Waveguide Aperture Covered by a Dielectric Slab

The input admittance of a circular waveguide opening onto an infinite flange with a homogeneous lossy dielectric coating is derived using integral transforms and assuming the dominant TE11mode as the trial field at the aperture. Admittance calculations for low-loss dielectric sheets of various thicknesses are given and compared with measurements obtained using ground planes of varying sizes. Excellent agreement with theory is obtained for the circular waveguide terminated into a square ground plane only1lambdato2lambda. on a side. A quantitative comparison of the surface wave contribution to the total admittance is also given.     

Design criteria for linearly polarized waveguide arrays

The influence of the waveguide aperture size on the admittance variation with scan angle of a waveguide phased array is presented. It is shown that certain size waveguide apertures can cause zero radiation directions. Design criteria which yield the maximum waveguide size to minimize or eliminate this condition are derived.     

The equivalent parameters for the radiating slot on a sectoralwaveguide

Formulas for the field components of the TE_pq, mode and the dominant mode TE₁₁ in a sectoral waveguide are given. Using the equivalence principle, the electric field distribution on the aperture surface of a narrow longitudinal slot cut in the curved broad wall of a sectoral waveguide is solved by the moment method (Galerkin's method). Important results such as the scattering parameters, the equivalent shunt admittance, and the resonant conductance and length are studied. The method used in this paper has good precision and has been adopted in the design of a linear slot array     

大型波导纵缝阵列天线的分析与设计

本文利用矩量法和等效网络法对矩形波导宽边纵缝阵列进行了精确的理论分析，严格计算阵中缝隙的内部和外部互耦，并利用等效网络法提取阵中缝隙的等效导纳特性。在此基础上，提出模型阵列和模型缝隙的大型波导缝隙阵的设计方法．理论结果与实验比较吻合。     

A new aperture admittance model for open-ended waveguides

A new model for the aperture admittance of open-ended waveguide structures radiating into a homogeneous, lossy dielectric is presented. The model is based on the physical and mathematical properties of the driving point admittance of passive, stable one-port networks. The model parameters, which depend upon the geometry of the waveguide and aperture, are determined from a relatively small number of computed admittances. This computed data is obtained by a full-wave moment method solution and, hence, includes the effects of radiation and energy storage in the near field and the evanescent waveguide modes. The accuracy of the numerical method is demonstrated by comparison with measured values. As an example, the model parameters are determined for the coaxial-line geometry. The accuracy of the model, for both the direct and inverse problem, is verified and a rigorous sensitivity and uncertainty analysis is performed. The new model has important applications in the field of dielectric spectroscopy     

The Filling Factor of Shielded Dielectric Resonators

The use of dielectric resonators at microwave frequencies usually requires a shield to prevent loss of energy by radiation, and a coupling network. The efficiency of a given circuit depends on the filling factor, which expresses the circuit ability to store most of the input energy in the resonator, and little in the coupling network and surrounding space. The resonator is sometimes excited by means of a coupling loop inside the shield, or with a propagating waveguide. In any case, some energy is stored outside the dielectric material. A calculation is presented for the internal and external stored energies, for the case of a rectangular dielectric resonator in a rectangular waveguide. Verification was performed by measuring the insertion loss of an acoustic delay line, which illustrates an interesting application of dielectric resonators.