Broadside-Coupled Slot-Line Field Components (Short Paper)

This paper presents expressions for the odd- and even-mode electric field components and also the magnetic field components in the air, overlay, and dielectric regions of the broadside-coupled slot-line structure. These expressions are numerically computed, and the fields in the cross section and the Iongitudinal section are illustrated. The surface current distribution on the metal surfaces are also illustrated.     

Slot Line on a Dielectric Substrate

Slot line consists of a narrow gap in a conductive coating on one side of a dielectric substrate, the other side of the substrate being bare. If the substrate's permittivity is sufficiently high, such as /spl epsiv//sub r/ = 10 to 30, the slot-mode wavelength will be much smaller than free-space wavelength, and the fields will be closely confined near the slot. Possible applications of slot line to filters, couplers, ferrite devices, and circuits containing semiconductor elements are discussed. Slot line can be used either alone or with microstrip line on the opposite side of the substrate. A "second-order" analysis yields formulas for slot-line wavelength, phase velocity, group velocity, characteristic impedance, and effect of adjacent electric and magnetic walls.     

Equivalent source analysis of curved edge tapered slot-line antennas

An equivalent source model for the analysis of curved edge tapered slot-line antenna is developed, which employs effective filamentary currents along the conductor edges of the slot, but forces the electric field produced by the currents to satisfy the boundary condition on the whole conductor surface. This idea is implemented by method of moments with collocation technique, and applied to analyze a tapered slot-line antenna with arbitrarily curved edge.     

Coupled Slot Line Field Components

The paper presents expressions for the odd- and even-mode electric field components and the magnetic field components in the air and dielectric regions of the coupled slot line structure. These expressions are numerically computed and the fields in the cross section and the longitudinal sections are illustrated.     

A Nonmodal Formulation for Electromagnetic Transmission through a Filled Slot of Arbitrary Cross Section in a Thick Conducting Screen

This paper considers the two-dimensional problem of electromagnetic transmission through a filled slot of arbitrary cross section in a thick perfectly conducting screen. The equivalence principle is used to divide the original problem into three isolated parts where postulated equivalent sources radiate into unbounded, homogeneous media. These equivalent electric and magnetic currents are chosen to ensure continuity of the tangential components of electric and magnetic fields at each aperture. An integral equation is written for each of the three parts with the equivalent currents as unknowns. The resulting set of coupled integral equations is solved by the method of moments. It is shown in the Appendix that this set of equations has a unique solution. The primary quantities computed are the equivalent magnetic and electric currents on each aperture and the electric current on the remaining portions of the slot cross section. These results are compared with those obtained from a modal solution, where the fields in the slot cross section are expressed in terms of parallel-plate waveguide modes.     

Slot-Line Filters and Couplers

The slot-transmission line on a dielectric substrate has many possible microwave circuit applications. This paper presents experimental data concerning the performance of bandpass and bandstop filters and a hybrid coupler; the work described was performed at S-band frequencies using the single substrate slot line geometry. Also included are theoretical data concerning the slot-line wavelength and characteristic impedance for the case of the slot-line configuration having dielectric material above and below the metsllization, the so-called slot-line "sandwich."     

Antenna-polarization and terrain-depolarization effects on pulse-radar return from extended areas at the near vertical

The methods now in the literature for calculating the terrain-backscattered radar-altimeter echo utilize the antenna power-gain patterns and the terrain radar cross section per unit area, usually designated σ0. In this paper, the polarization characteristics of the antennas and the echo depolarization by the terrain are taken into account for the first time. The formulas for the backscattered return are presented in terms of antenna and terrain parameters that can be measured directly or calculated from other measurements. These parameters are the four transmitting- and receiving-antenna gain patterns for the orthogonal polarization components, the two functions giving transmission- and reception-phase difference between the polarization components, the terrain-depolarization factor that accounts for the average backscattered power cross polarized with respect to the incident wave, and the radar cross section σ0per unit area. It is shown that the older formulas used for radar return from the near vertical are correct only when both antennas are linearly polarized and have the same direction of polarization. The errors that result from failure to consider polarization effects are illustrated by examples.     

Microstrip-Slot Coupler Design-Part II: Practical Design Aspects

Practical aspects of designing microstrip-slot couplers on an Al/sub 2/O/sub 3/ ceramic substrate (epsilon/sub r/ = 9.8) are treated in supplementation of the theoretical analysis of the coupler presented in Part I. Comparison with implemented couplers yields rules for specification of the reference planes at the ends of the coupling section, for the appropriate choice of definition for the slot-line characteristic impedance. Design data of the standard versions of the microstrip transmission line, the slot line are shown to be adequate for the microstrip-slot coupler. Computed S -parameter curves plotted for various 3-dB couplers yield information on realizable transmission characteristics.     

Admittance of a longitudinal waveguide slot radiating into anarbitrary cylindrical structure

In this paper we use a hybrid method to calculate the admittance of a longitudinal slot (of finite length) in a rectangular waveguide, when the slot radiates into a cylindrical outer structure of arbitrary finite cross section. The analysis takes advantage of a Fourier transformation along the cylinder axis, by which the computational effort is drastically reduced. The harmonic spectral currents on the structure are expanded in subsectional triangular basis functions and determined using an electric field integral equation (EFIE) and the moment method. These currents and the corresponding fields are inverse Fourier transformed and matched over the slot to the fields inside the waveguide by an additional moment method approach using entire domain basis functions for the slot field. The calculated slot admittance has good accuracy when compared with measurements on a chosen geometry     

Miniature high-Q double-spiral slot-line resonator filters

A new class of low insertion-loss miniaturized filters using slot-line resonators is proposed. Miniaturization is achieved by terminating the slot line with a double-spiral inductive termination at both ends. Using this miniaturized resonator, both positive and negative couplings may be realized, and therefore, both standard coupled-line and cross-coupled quasi-elliptic filters are realizable. The unloaded Q of these slot-line filters is considerably higher than that of miniaturized microstrip filters of comparable dimensions due to the inherent higher Q of the slot line. To demonstrate the validity of the design procedures and the performance characteristics, two different types of filters were fabricated and tested. One is a four-pole Chebyshev filter and the other is a quasi-elliptic filter where, in each case, the full-wave simulations show very good agreement with measurements.     

Output performance of a slot in a waveguide with dielectric insert of finite length

Characteristics of a narrow longitudinal slot positioned over a dielectric insert of finite length completely filling the cross section of a rectangular waveguide have been investigated. The magnetic field excited by a slot in the dielectric insert in the area directly under the slot was determined. Internal admittance of the slot and its energy parameters were numerically investigated.     

基于缝隙单元的3D多模频率选择结构研究

为了实现高性能的滤波响应,提出了一类新型基于缝隙单元的三维多模频率选择结构。首先以传统2D“十字”缝隙型频率选择表面及其级联结构为例,阐述了2D频率选择表面在结构、性能上的优缺点。为了进一步改善滤波性能,分别提出了基于均匀缝隙单元、阶梯阻抗缝隙单元、多模吸波式缝隙单元的3D频率选择结构。该类型频率选择结构可基于传输线理论进行分析,在设计频段内可产生多个谐振模式而展现出高性能滤波响应,故在微波毫米波频段具有良好的应用前景。     

Sandwich Slot Line (Correspondence)

Formulas and curves are given for the relative wavelength and characteristic impedance of sandwich (double-substrate) slot line. A field plot shows that the slot-wave field components are closely confined to the vicinity of the slot, and the H field is elliptically polarized near the outer surfaces of the sandwich.     

Synthesis of configuration of uniformly radiating longitudinalslots in the sections of nonregular rectangular waveguides

The integral-equation method has been applied along with perturbation theory to investigate the leaky-wave parameters of the fundamental mode in the regular waveguide with a narrow longitudinal slot on its broad wall, opened into shielded semispace. Then, the simple analytical formulas have been derived for the engineering synthesis of radiating elements (REs), which are formed by a nonuniform waveguide section with a nonregular slot on its broad wall. The long slot was cut in the longitudinal direction along certain curved or several connected broken lines, forming small local angles with the waveguide axis. The synthesis of RE's by single-mode approximation has been carried out for the condition of good uniformity of radiating electrical-field distribution along the RE axis near the slot. Good agreement of theoretical and experimental results was obtained     

Cutoff Wavelengths of Ridged, Circular, and Elliptic Guides

Cutoff wavelengths of TE and TM modes in doubly ridged guides of elliptical cross section have been calculated using an exact method. Closed-form expressions in terms of Mathieu functions have been obtained for the cutoff frequencies and eigenfunctions describing the field distribution for different modes. These solutions are further extended to include the case of doubly and quadruply ridged guides of circular cross section and to calculate the slot coupling of two waveguides with semielliptical or circular cross sections. The dual problem of the coaxial strip guide has also been treated using the same method.     

TE-case RCS analysis of finite-thickness slotted circular cylinder loaded with lossy filling

A generalized model is developed to study the TE-polarized plane wave scattering by coated and uncoated slotted circular cylinders of nonzero thickness and by a filled and not filled circular cylinders with sectorial cuttings. The mathematical treatment is based on the coupled integral equations (IEs) with respect to the tangential electric field at the slot/cutting apertures. The Galerkin method with weighted Gegenbauer polynomials as basis functions is used to convert IEs to a set of linear algebraic equations. Numerical simulations of the radar cross section (RCS) are carried out in the case of single slot/cutting in order to reveal the effect of thickness. Potentials of three approximations to the field in the slot/cutting domain are studied. Their use enables one to substantially accelerate the RCS calculations.     

Si基槽型光波导的传输特性分析和传输损耗的测量

对Si基槽型(slot)光波导的传输特性进行了研究。 采用三 维时域有限差分(3D-FDTD)法研究了芯层中的光功率与波导槽型宽度及Si条带宽度之间的关 系,结果显示,槽型光波导具有很好的光功率约束效率,可以达到30%以上; 分析了光功率的变化规律及其优化,综合考虑光功率和光功率密度确定波导结构参数,实现 最佳光功率分 布,横向光功率分布沿x轴方向具有很好的约束效果,沿y轴方向呈现高斯分布;分析了底部Si薄层对光 功率的影响,100nm的底部Si薄层使得芯层的光功率下降50%,减小 底部Si薄层厚度有利于光功率约束效 率的提高;采用电子束刻写(EBL)技术和等离子刻蚀(ICP)技术制备了Si基槽型光波导,实验 研究了其传输损耗,结果显示,槽型光波导具有较低的传输损耗,达到13.5dB/cm。     

A New Class of Nonreciprocal Components Using Slot Line (Short Papers)

The authors present an experimental and theoretical study of edge modes in a ferrite-loaded slot line. Nonreciprocal properties are obtained over a broad frequency band. Added microstrip lines provide suitable transitions. A theory based on magnetic boundary conditions shows good agreement with the experimental results and allows a comparison with stripline devices described by Hines. In particular, the characteristics of the slot-line isolators are satisfactorily explained by this theory.     

The RCS of a metal plate with a resonant slot

A numerical method based on the thin-wire electric field integral equation is used to calculate the radar cross section (RCS) of a wire grid with a resonant slot. The numerical results are in good agreement with experimental data for a wire grid, where the antiresonance is found to occur at a slightly lower frequency than a similarly slotted plate.     

Microstrip-Slot Coupler Design-Part I: S-Parameters of Uncompensated and Compensated Couplers

Using the even-odd mode analysis of four-port networks with double symmetry, the scattering parameters of the microstrip-slot coupler are derived from the even- and odd-mode parameters of the coupler cross section. The uncompensated coupler and the coupler compensated by extending the slot fines are treated and design specifications are given covering the compensation slot lines. A comparison with experimental data will be given in Part II.