Analysis of a wide radiating slot in the ground plane of amicrostrip line

An analysis of a wide rectangular radiating slot excited by a microstrip line is described. Coupled integral equations are formulated to find the electric current distribution on the feed line and the electric field in the aperture. The solution is based on the method of moments and using the space domain Sommerfeld-type Green's function. The information about the input impedance or reflection coefficient is extracted from the electric current distribution on the microstrip line utilizing the matrix pencil technique. The theoretical analysis is described and data are presented and compared with other theoretical and experimental results     

Analysis of a thin slot discontinuity in the reference plane of amicrostrip structure

This paper presents a perturbational approach based upon the spectral domain technique for the analysis of the discontinuity effects introduced by a thin slot in the ground plane of a microstrip line. The discontinuity problem is formulated in terms of the unknown slot field by using the notion of equivalent half-space problems, using a new rigorous procedure for deriving the TE-TM decomposition of the fields and equivalent transmission line models. The perturbation current on the infinite microstrip is computed once the electric field in the slot has been derived, and an equivalent circuit for the discontinuity is obtained from this perturbation current for the low-frequency regime. Computed results are presented and compared to the measured data     

Impedance of a transverse slot in the ground plane of an offset stripline

A generalized formulation for the determination of the impedance of a transverse slot in the ground plane of an offset stripline is presented. The results of the analysis are used to compute the variation of slot impedance with strip offset and also with change in position of one of the ground planes. Comparison of the theoretical results with experimental data is presented.     

Analysis of an array of line sources above a finite ground plane

A simplified analysis which gives insight into and physical interpretation on the radiation mechanism of an array of line sources above a finite ground plane is presented. Computations have been restricted to an array of two line sources since data are available for comparison. Results on the variation of the maximum field intensity, the angle of maximum field intensity, and the field intensity at the axis of the counterpoise as functions of the size of the ground plane are presented. Variations of the maximum field intensity and the angle of maximum field intensity as functions of the distance of the source above the ground plane are also illustrated. These data become very important in the design of antennas for aircraft navigation taking into account the presence of the finite counterpoise which otherwise could lead to erroneous designs.     

Reflectarray element using variable ring with slot on ground plane

A novel structure using a variable microstrip ring with a slot ring on part of the ground plane is proposed as an auxiliary unit cell in a reflectarray. A progressive phase range larger than 682° has been achieved by changing the sizes of the microstrip rings and adding slot rings on part of the ground plane. A K-band reflectarray has been fabricated and shows very good performance.     

Effects of ground plane dimensions on patterns radiated by slot antennas

Using a hybrid MoM-UTD formulation, this paper investigates the effects of ground-plane dimensions on the radiation fields of a slot antenna. It is shown that the radiated field strength of a slot cut in a finite ground plane is generally higher than that of a similar slot in a ground plane of infinite extent. Indeed, computational results reveal that the E-plane radiated field strength of a slot is about 3 dB higher when the ratio of the ground plane width to slot length is an even integer; and 1 dB higher when the ratio is an odd integer. In the case of the H-plane, the field strengths radiated by a slot in both infinite and finite sized ground planes are virtually identical, suggesting, therefore, that in this case, the contribution of the edge diffraction is insignificant. Results also indicate that a ground plane thickness of less than 20 mm has negligible effects on the radiation fields, as the strength of coupled fields, which is a manifestation of the effect of the finite thickness of the ground plane, is very small. As a validation, patterns computed compare favourably with experimental data available in the literature.     

A dual-band dual-polarized nested Vivaldi slot array with multilevel ground plane

In this paper, we present a systematic approach to the design, optimization and characterization of a broadband 5:1 bandwidth (0.8 to 4.0 GHz) antenna subarray. The array element is an optimized-taper antipodal Vivaldi slot with a bandwidth of 2.5:1. Two such elements of different sizes and with 0.4 GHz (10% of the highest frequency) overlapping bandwidths are arrayed in a nested lattice above a multilevel ground plane that shields the feeds and electronics. Return loss, radiation patterns, cross-polarization and mutual coupling are measured from 0.5-5.0 GHz. This array demonstrates E plane patterns with 50/spl deg/ and 45/spl deg/ 3-dB beamwidths in the lower and upper frequency bands, respectively. The coupling between the elements is characterized for different relative antenna positions in all three dimensions.     

Characterization of small apertures in the center conductor of amicrostrip line

A closed form expression for the series reactance of an electrically small aperture in the center conductor of a microstrip line is determined using equivalent dipole moments due to the aperture and employing a quasistatic approach. The reactance of an inclined slot and a diamond shaped aperture are evaluated as a function of the aperture geometry in the lower microwave frequency band. The results based on this analysis are compared with those obtained from Oliner's formula. Experimental results are in fairly good agreement with the results obtained using the proposed theory     

Effect of ground plane absorption coefficient on the admittance of a slot antenna radiating into a warm lossy plasma

The effects of the ground plane electron absorption coefficient on the admittance of a half-wavelength slot antenna radiating into a warm lossy plasma are examined for a range of plasma conditions and slot widths. The ground plane absorption coefficient is observed to have significant effects on the admittance of a thin slot when the plasma is greatly overdense, even when the plasma is only mildly warm (T_{e} leq 1 eV).     

Radiation from a slot antenna in a ground plane coated with a moving plasma sheath

The electromagnetic radiation from a slot antenna in a conducting plane coated with a moving isotropic cold plasma layer is considered. It is assumed that the direction of motion of the layer is across the slot, which is taken to be infinitely long. An integral representation for the field radiated through the plasma layer is obtained and evaluated asymptotically in the far zone by the method of steepest descents. The migration of the poles in the integrand of this integral representation as the speed of the slab is varied is discussed and related to several calculated radiation patterns. It is found that the motion of the plasma layer has the greatest effect on the radiation pattern when the wave frequency and plasma frequency are nearly equal.     

Analysis of coupled slot resonators of complex shape in metalization plane of a micro-strip transmission line using the transversal resonance techniques

The transverse resonance techniques is developed for analyzing three-layer planar structures based on micro-strip transmission line with slot resonators of complex shape in the grounding plane. Development of the techniques consists in considering higher space harmonics of current density in the strip line and mutual coupling between the slots in the grounding plane when numerically solving the boundary problem. In order to verify the techniques we conduct analysis of structures that consist of two coupled U- and symmetrical H-shaped slot resonators in the grounding plane of the micro-strip transmission line.     

A full-wave characterization of an interconnecting line printed ona dielectric slab backed by a gridded ground plane

The electromagnetic behavior of a planar structure formed by a conducting strip printed on a dielectric slab backed by a gridded ground plane is analyzed in order to outline the characteristics of this type of interconnect often used in microwave integrated circuits and digital applications. A two-port equivalent model, based on the Z-matrix network representation, is adopted to study the electrical properties of the structure. The Z-parameters have been determined by means of a full-wave spectral domain methodology. Numerical results concerning the properties of this type of interconnect for different grid geometries are presented, and the effects related to the radiation from the strip and the gridded ground plane are pointed out     

An inverse problem for line and strip sources of electromagnetic field above an imperfectly conducting ground plane

An analytic method of solving the inverse problem of determining the optimal excitation of line and strip sources of electromagnetic fields generating given directional functions above an imperfectly conducting ground plane is presented. The method used is based upon algebraization of the problem. The overdetermined system of equations obtained is solved by the method of generalized matrix inverse and the method of regularization of Tikhonov. An error estimate, criteria for the choice of parameters, and an experimental procedure are given. Numerical examples related to airborne radionavigation illustrate the application of the theory.     

Diffraction of a plane wave by an inclined parallel plate grating

The diffraction of a plane electromagnetic wave by an inclined parallel plate grating is treated by using the Weiner-Hopf technique. The problem is formulated in terms of the single Wiener-Hopf equation, which is then using a factorization and decomposition procedure. The solution is exact but formal in the sense that there is an infinite number of unknowns. Approximation procedures are presented and two forms of the approximate solution are derived. Based on the above analysis, numerical examples are given and the transmission characteristics of the grating are discussed     

Rigorous analysis of a circular patch antenna excited by amicrostrip transmission line

Boundary conditions are enforced on a portion of the microstrip feed line as well as the patch antenna. The integral equation for the unknown currents on the antenna and feed is solved by applying the Galerkin method of moments in the Fourier transform domain. The validity of the solution is tested by comparison of computed results with experimental data. The theoretical treatment proves to be applicable to the most common feeding arrangements, namely, the direct edge-feed and proximity coupling excitation. In the latter case, two-layer substrates having distinct dielectric constants are studied. The purpose of the study is to deduce, for a given overall substrate thickness, the smallest line-ground plane separation for which a match of the radiator to the feed line is still possible. The advantages of such a configuration are discussed     

波导窄边斜缝行波阵列天线设计

为了快速设计波导窄边斜缝行波阵列天线,采用理论计算结合软件仿真的方法。利用电磁仿真软件HFSS模拟实验过程,得到裂缝电导函数。初始设计完成后,比较仿真结果口径分布和理论口径分布的差异,微调裂缝尺寸参数使天线口面幅度逼近设计值。设计了一个47阵元行波线阵,并采用两根波导对称放置抑制交叉极化。Taylor综合副瓣值为-30 dB,仿真得到的最大副瓣值为-24.8 dB,波瓣宽度为2.2°,增益为24.6 dB。     

螺旋地板式电磁带隙结构的传输特性分析

为了实现电磁带隙结构(Electromagnetic Band Gap,EBG)的小型化,提出了一种螺旋地板式电磁带隙结构,即通过在接地金属板上加载螺旋结构的方法来减小谐振频率,实现EBG单元结构的小型化,并用HFSS软件建立结构仿真模型,分析了螺旋线单元长度变化对电磁带隙特性的影响规律。结果表明增加螺旋线单元长度可以使频率带隙向低频方向移动。最后,将地平面加载与未加载螺旋结构的两种EBG进行仿真分析。结果表明,螺旋地板式EBG能够抑制更低频段的电磁波,达到了EBG单元结构小型化的目的。     

Radiation through an inhomogeneous plasma covering a ground plane

Electromagnetic radiation from a slot-excited ground plane covered by a plasma layer with exponentially decreasing electron density is considered. It is found that the far-field radiation pattern is simply related to that found for the case where the layer is absent.