A hybrid dielectric slab-beam waveguide for the sub-millimeter waveregion

A hybrid dielectric-slab-beam waveguide is suggested which should be well suited as a transmission medium for the design of planar quasi-optical integrated circuits and devices operating in the millimeter- and sub-millimeter-wave regions. The guide consists of a grounded dielectric slab in which a sequence of equally spaced cylindrical lenses is fabricated. The center line of the slab guide is the axis of the lenses. The structure uses two distinct waveguiding principles in conjunction to guide electromagnetic waves. In the direction normal to the slab surface, the guided fields behave as surface waves of the slab guide; their energy is largely confined to the interior of the dielectric and they are guided by total reflection at the slab surface. In the lateral direction the waves behave as Gauss-Hermite-beam modes that are guided by the lenses, which periodically reconstitute their cross sectional phase distribution, resulting in a wave beam that is iterated with the lens spacing. The guided fields are in effect TE and TM modes. The analysis of the new guiding structure is analyzed, the mode spectrum is calculated, and the iteration loss due to the finite size of the lenses is estimated     

Millimeter Wave Antenna with Scanning Beam

The results of theoretical analysis and experimental investigation of the millimeter waves antenna with scanning beam are presented. The operation concept of the antenna is based on the effect of transformation of the surface waves of dielectric waveguide in the volume waves. The smooth space scanning of beam has been made by means of change of wave propagation constant inside of the dielectric waveguide. All experiments were made in the four-millimeter wave range. The angle of scanning was Θ=35° and width of directional diagram was 2° in the scanning plane. The lens and the mirror antennas were designed.     

Dual-Frequencies Diffractive Lenses at Millimeter Wavelengths

Diffractive lens have many advantages over refractive lens at millimeter waves band, such as thin, light and low dielectric loss and so on. However, diffractive lens have chromatic aberration, that is, focusing performance of diffractive lens is frequency dependent. In this report, a dual frequencies diffractive lens is developed, which can work at 8mm band and 3mm band, based on the harmonic diffractive lens techniques. Experiments show it has almost same focusing performance at 8mm band and 3mm band.     

Lenses and graded films for focusing and guiding acoustic surface waves

Two novel schemes for guiding acoustic surface waves along curved paths on isotropic substrates are described. One involves the deposition of a slowing film of graded thickness along the intended path on a dielectric substrate. Paraxial-ray equations are developed to describe the ray paths adjacent to the axis of the guiding film, which are determined by the slowing factor resulting from a variable-thickness deposited film. Diffraction is taken into account through an approximation developed by Pierce for optical beams. It is shown that very thin films are sufficient for a substantial amount of directional control. The other guidance system employs a series of lenses in analogy with the lens guides developed for millimeter waves and optical beams. Some comments are made about thin-film lenses and the theory is developed for the focusing action of a lens formed by a spherical depression in (or protrusion from) the surface of a substrate. A simple analog for determining ray paths over generally nonplanar surfaces is described and applied to nonspherical depressions to evaluate their focusing properties.     

New nonlinear magnetostatic surface waves in a ferromagnetic (YIG)

The general propagation characteristics of magnetostatic surface waves guided by a single interface of a semi-infinite nonlinear dielectric cover and a ferromagnetic substrate (YIG) have been derived. The nonlinear dielectric cover has intensity dependent refractive indices. The magnetostatic approximation is considered and retardation is ignored in describing the electromagnetic fields in the structure. The used magnetostatic approximation is leading to new waves and might be called nonlinear magnetostatic surface waves. The propagation of these waves is non-reciprocal in contrast to the linear magnetostaic surface waves, which had been only found in the negative direction of propagation.     

反铁磁晶体的红外频率特性

研究了红外频段非线性s偏振表面波在反铁磁晶体和电介质交界面上的频率特性，求出了非线性色散方程，揭示了非线性s偏振表面波存在一个临界频率，低于这个频率，非线性s偏振表面波的频率范围，发现功率不再是决定导波频率范围的唯一因素，两种材料的介电常数比在这里起了至关重要的作用。     

A novel quasi-optical resonator for the surface near-millimeterwaves

The theory and experimental investigations are presented for a new type of quasi-optical near-millimeter-wave prismatic resonator, which provides frequency selective transformation of the plane waves into the surface waves. Theoretical expressions are obtained for the Q-factor and finesse, which consider dielectric loss and the effect of prism finite aperture. The theoretical evaluations are verified by experimental measurements in the frequency range 300-500 GHz using a prismatic resonator made from the optical quality fused silica glass. The increase of intensity of surface waves by a factor of 10-25 is demonstrated for the prismatic resonator made from an extremely low-loss dielectric     

High-frequency analysis of integrated dielectric lens antennas

A high-frequency method for the three-dimensional analysis of integrated dielectric lens antennas is presented. This method consists on improving the physical optics (PO) currents on the lens surface by modifying, via suitable transition functions, the spreading factor of those rays from the source point which arrive at the lens-air interface close to the critical angle of incidence. Invoking the locality principle of the high-frequency phenomena, the method uses the rigorous canonical solution of the semi-infinite dielectric space locally tangent at the lens surface. A uniform asymptotic evaluation of this canonical solution is provided with the introduction of a new transition function for the TM case. The present formulation provides significant correction from the PO currents of an elliptical lens, with a consequent improvement of the radiation pattern prediction, testified by comparisons with results from a full-wave analysis.     

Diffraction by a cylinder with a dielectric shell. Surface waves and an antiradar coating

The field formed during diffraction by a circular cylinder with a dielectric shell can be represented in the form of a Watson series, i.e., as a set of azimuthal waves. The structure, velocity, and attenuation of these waves are found. It is shown that the process during which surface waves excited in the presence of diffraction by any guiding nonplanar surface carry away a portion of the incident energy and reduce the scattered wave can be used for creating a coating in the form of a dielectric layer.     

光路中使用准直透镜时应注意的一个问题

在准直光路中,经过准直透镜后,除得到一束平面波外,由于透镜前后表面的反射,还附加产生一个会聚在ｆ（ｎ － １）／２ｎ处的球面波。本文给出了理论推导和实验验证,并讨论了在全息光路中使用准直透镜时应该注意的问题     

多层介质型太赫兹菲涅尔天线研究

基于菲涅尔波带片透镜的设计原理,设计了三款多层介质结构的菲涅尔波带片天线.该天线采用高增益的波纹喇叭天线提供馈电,工作频段为太赫兹通信第一大气窗口320～380GHz,回波损耗低于-15 dB,增益大于25 dBi.研究了菲涅尔波带片天线的周期数和子区数对天线性能的影响,结果表明随着周期和子区数的增加,增益也会不断的提高,而当波带片直径和喇叭口径面积相比拟时,电磁波损耗较大,并且谐振频率在太赫兹大气窗口内右移.     

Magnetostatic surface waves in a ferrite/dielectric/metal-strip-grating structure

The dispersion relation for magnetostatic surface waves in a ferrite/dielectric/metal-strip-grating structure is obtained. It is shown that dispersion of magnetostatic surface waves must be qualitatively the same as in a ferrite/dielectric/metal structure, while the slope of the dispersion curve in the region of backward magnetostatic waves existing in a ferrite/dielectric/grating structure (and in a ferrite/grating structure in particular) is considerably higher than the slope of this curve corresponding to a ferrite/dielectric/metal structure. It is found that this phenomenon can be explained by the dependence of the grating’s shielding capability on the wave number of magnetostatic surface waves. A grating shielding parameter is introduced and dependences of this parameter on the wave number that can be used to explain the phenomena observed in the experiment are determined.     

波导参数和传播常数对光折变表面波的影响

基于质点振荡的模型和数值模拟的方法,研究了波导参数和传播常数对光折变晶体与线性电介质界面光折变表面波类型和局域表面波模的影响。当波导参数大于传播常数时,在光折变晶体与线性电介质界面可以产生非局域表面波。当波导参数小于传播常数时,在光折变晶体与线性电介质界面可以产生振荡表面波和局域表面波。在局域表面波形成的系统内,正波导参数的光波能量比负波导参数的光波能量在光折变晶体内聚集得多。在给定一个局域表面波形成的物理系统,传播常数越大,表面波在线性电介质和光折变晶体中衰减就越快,对应表面波模的波峰离界面就越近。     

Surface wave along a ferrite rod magnetized below saturation

Surface waves supported by a ferrite rod, magnetized longitudinally near and below saturation, are studied experimentally using the surface wave resonator technique. Two types of slow waves are found to exist. Their propagation constants depend on the dc magnetic field and rod size. They are interpreted as theHE_{11}mode positive and negative circularly polarized surface waves. For pure circularly polarized waves, a magnetized ferrite is considered as a dielectric with nontensor permeability. A calculation of the propagation constant of these circularly polarized surface waves, based on the dielectric analogy, is made. The agreement between calculation and measurement is close.     

TM Nonlinear electromagnetic waves guided by an inhomogeneous medium

Analytical dispersion relations and the power flow expression for TM (polarized) nonlinear electromagnetic surface waves propagating along the interface of an inhomogeneous and dielectric nonlinear media have been investigated theoretically. An inhomogeneous dielectric cover has the dielectric permittivityε=a+bz, which is contacted with a strongly nonlinear Kerr like layer. The existence conditions for these waves to be propagated are studied. These waves have no counterpart in the linear isotropic regime. The power flow versus the wave index, and the consequence interface nonlinearity might be evaluated for a variety of inhomogeneity parameters, which are found to be inhomogeneity dependent, and could lead to optical hysterisis and bistability.     

Electromagnetic waves of dielectric structures in plasma

The electromagnetic waves of a dielectric layer and of a dielectric cylinder in homogeneous infinite plasma are considered. The dispersion dependences of surface and volume-surface E and H electromagnetic waves are investigated. A classification of the waves of dielectric structures in plasma is proposed.     

Surface wave modes of printed circuits on ferrite substrates

Surface waves due to a current source on a grounded ferrite slab are investigated. Electromagnetic fields of the structure are in terms of a continuous plane wave spectrum. The spectrum of each field component is obtained numerically through the exponential-matrix method. The surface waves of the structure are extracted from the continuous spectrum by using the residue theorem and the method of steepest descent. Two types of surface waves are found and their properties are described. The surface wave modes found include dynamic surface wave modes which are closely related to the surface waves of a grounded dielectric slab, and magnetostatic surface wave modes which are related to the solution of Laplace's equation for the magnetic potential     

Effects of surface waves on the currents of truncated periodic arrays

The behavior of surface waves in truncated periodic arrays is examined through analysis of the currents. The surface waves to be studied are guided by the perfectly conducting elements of the array itself and are to be distinguished from the dielectric slab-guided surface waves encountered elsewhere in the literature. The conditions under which surface waves may arise are given. The surface wave currents are extracted from the method of moments solution for the finite by an infinite array using a least squares algorithm. Surface wave excitation and reflection coefficients are then be determined from the data and compared with the semi-infinite array solution.     

A surface wave interpretation for the resonances of a dielectric sphere

The calculated radar and bistatic cross sections of dielectric spheres exhibit numerous resonances when plotted versus frequency. These resonances may be related to the excitation of electromagnetic eigenvibrations of the sphere, with resonance frequencies calculable from a characteristic equation. It is shown that the resonances may be viewed as originating from families of circumferential (surface, or creeping) waves that are generated during the scattering process; at each eigenfrequency of the sphere, one of these surface waves matches phases after its repeated circumnavigations around the sphere, with the ensuing resonant reinforcement leading to the given scattering resonance. This mechanism explains the existence of electromagnetic eigenvibrations of a general smooth dielectric object; for the case of a sphere, it is shown that the surface waves suffer a phase jump ofpi/2at each of their two convergence points. We calculated numerical values of the eigenfrequencies of dielectric spheres, and obtain dispersion curves for the phase velocities of the surface waves.     

探地雷达天线近地效应研究

微带天线应用于探地雷达技术领域时,实验测得的各种电参数与自由空间相应的电参数总有一定的偏差,这种偏差称之为近地效应.文中对天线贴地后有效介电常数的计算公式进行了修正,并应用该修正式对探地雷达天线回波频率进行了模拟计算,将计算结果与实验结果进行了对比,研究表明,有效介电常数的变化是产生近地效应的一个重要原因.