Hexagonal boundary Sierpinski carpet fractal shaped compact ultrawideband antenna with band rejection functionality

In this paper a second iteration Sierpinski carpet fractal shape UWB antenna with hexagonal boundary is presented. The antenna covers the frequency band from 3 GHz to 12 GHz (VSWR ≤ 2). The proposed antenna has the capability to reject 5.15–5.825 GHz band assigned for IEEE802.11a and HIPERLAN/2 which is achieved by embedding a ‘Y’ shaped slot in the radiator that extends to the central conductor of the CPW feed as well. A fabricated prototype is developed where the simulation and experimental results are in good agreement. Measured peak antenna gain varies from 1.25 dBi to 6 dBi within the band. The proposed antenna has a compact size of 33 mm × 32 mm that includes the substrate around the radiating element. Time domain characteristic reveal that the antenna is non-dispersive with a variation of measured group delay within 0.5 ns over the entire band.     

Design and analysis of microstrip photonic band gap filter without etching ground plane

A design of microstrip photonic band gap (PBG) filter is presented in this paper. The band reject filter is compact in structure and provides accurate band gap. The proposed filter has a periodic configuration; the impedance distribution over the length of each period is varied according to a designated sinusoidal function. Both theoretical and experimental results indicate that a bandstop filter with an extremely wide bandwidth can be achieved. Detailed analysis of the frequency response of the PBG filter is carried out in this paper.     

Microstrip Sierpinski fractal carpet for slot antenna with metamaterial loads for dual-band wireless application

The compact microstrip antennas with the dual-band characteristic and reconfigurable qualification have been noticed and investigated in this paper. We have developed the slot microstrip antenna with Sierpinski carpet and Minkowski formations and then the metamaterial loads are placed on this antenna in the slot area. The reflection/transmission method has considered to obtain the permittivity and permeability of the split ring resonator (SRR) as a metamaterial. Finally, we show that by using some junction in the metamaterial layer, we can obtain reconfigurable characteristic. Both antennas have dual-band characteristic where the first antenna has two resonances at 3.2 and 4.5 GHz and in the second antenna by altering the metamaterial layer both resonances are occurring at 3.5 and 5.8 GHz. We show that the antenna has two resonance frequencies that matched with the metamaterial Double Negative (DNG) characteristic. Both antennas are printed on FR-4 also we compared measurement and simulation results together. Aforementioned antennas cover the main wireless, WiMAX and LTE bands with sufficient gain and high efficiency (more than 80% typically) with a bi-directional radiation pattern for the indoor application. Here, the metamaterial is used for controlling the resonances and Sierpinski carpet is developed for matching.     

Fast analysis for electromagnetic band gap waveguides using compact finite-difference-time-domain method

A fast analysis method, cell modified compact finite-difference time-domain method (CMC-FDTD), is presented to analyze the performance of electromagnetic band gap waveguides. The method calculates band diagrams in orthogonal coordinate system by translating nonorthogonal lattice to orthogonal lattice. It has highly stability for calculating dielectric and metallic material, either TE or TM mode, and reduces the requirement for memory. The comparisons are made among two numerical results and experimental one to validate the method.     

Radiation and scattering analysis of infinite arrays of endfireslot antennas with a ground plane

A Green's function moment-method analysis of infinite arrays of endfire slot antennas is described that includes the constant width slot antenna (CWSA) and the linearly tapered slot antenna (LTSA), with a ground plane. The method utilizes an application of equivalence at a plane in front of the array which facilitates the extension of this analysis to antennas printed on protruding dielectric sheets and/or the addition of a radome. Numerical calculations are compared with waveguide simulator experiments for CWSA and LTSA arrays as well as several less complex problem. Relevant numerical considerations and convergence issues are also discussed     

Rectangular microstrip patch antennas with infinite and finite ground plane dimensions

The rectangular microstrip patch antenna has been extensively analyzed with regard to its input impedance and resonant frequency, both for infinite and finite ground plane dimensions. For infinite ground planes existing formulas have been compared and improved parameters presented. The influence from the side current radiation has been discussed as well. For finite ground plane dimensions the contribution from the ground plane edge diffraction has been accounted for in an equivalent radiation conductance and an equivalent diffraction susceptance. Formulas for these parameters have been developed on the basis of different theories. They are valid under the condition that only one of the ground plane dimensions are finite at the same time. Experimental investigations are carried out to test the accuracy of the developed formulas, showing good accuracy under the given conditions.     

A modified ground apollonian ultra wideband fractal antenna and its backscattering

This paper presents the design of a modified ground apollonian ultra wideband (UWB) fractal antenna. The printed fractal antenna has been designed on a substrate with dielectric constant ?_r = 4.3 and thickness h = 1.53 mm. The antenna has been fabricated with optimized dimension and tested. The experimental result of this antenna exhibits UWB characteristics from frequency range 3 GHz to 18 GHz. This corresponds to 142.86% impedance bandwidth with center frequency of 10.5 GHz. The experimental radiation patterns of this antenna are nearly omni-directional in H-plane and bidirectional in E-plane. The effect of various design parameters on UWB characteristics have also been analyzed using a 3D electromagnetic simulator based on FEM method. The simulated and experimental results are in good agreement. The backscattering RCS of this UWB fractal antenna is better than ?31 dB throughout the FCC band (3.1 GHz to 10.6 GHz). The proposed coplanar waveguide feed appollian fractal antenna can be easily integrated with radio-frequency/microwave circuitry with low-manufacturing cost and useful for UWB applications.     

基于Pocklington型积分方程式的有限间隙馈电实芯圆柱天线的分析

使用在馈电函数中含有磁流项的Poclington型积分方程式对实芯圆柱天线进行了分析．对于精确地求解存在于实芯圆柱天线外表面的电流分布时，该磁流项是必须考虑的．一个在馈电间隙上满足边缘条件的电场分布被使用，基于该电场分布的数值解析结果与试验结果，以及利用馈电间隙上的均匀电场分布所求解的结果进行了比较．     

具有屏蔽腔和吸波材料的探地雷达天线的FDTD分析

天线是探地雷达系统的关键部件之一,系统要求天线具有较好的辐射波形以及一定的隔离度.给出了一种可用于探地雷达系统的分布电阻加载的变形TEM喇叭天线,并且采用三维FDTD方法分析了屏蔽腔和吸收材料对其辐射特性的影响.计算结果表明,通过加入屏蔽腔和吸收材料,可以减小收发天线之间的直耦信号,使目标回波信号更加明显,从而提高了系统的动态范围.     

A novel technique for analysis of electromagnetic scattering frommicrostrip antennas of arbitrary shape

A new numerical procedure is developed for the solution of the electric field integral equation (EFIE) for arbitrary-shaped microstrip structures. This approach is superior over conventional EFIE techniques particularly in the low-frequency region or where the structure to be analyzed is electrically small. A pair of new basis functions is presented which are essential to the solution in the entire frequency range of interest. The new basis functions decompose the surface current density into divergenceless and curl-free parts which essentially get decoupled at the very low end of the frequency spectrum. Typical numerical results are presented for certain examples to illustrate the difference in the results between the two methods     

A physical basis formulation for the electromagnetic backscatteringby a finite-length rectangular trough in a ground plane

The electromagnetic backscattering from a finite-length rectangular trough in an infinite ground plane is examined. A physical basis formulation is used to express the unknown currents in the trough aperture in terms of a forced wave resulting from the incident plane wave, and one or more pairs of oppositely directed traveling waves propagating along the trough. A Galerkin solution is employed to solve a very small system of equations to determine the weights of the postulated aperture currents, and then radiated to compute the radar cross section (RCS). These results are then compared with a measurement of a trough in a finite ground     

A simple and accurate model for microstrip structures with slotted ground plane

A simple and accurate circuit model for microstrip filtering structures with slotted ground plane is presented. The unit cell model consists of a series inductance and shunt capacitance for the microstrip line, an ideal transmission line characterized by its impedance and electrical length for the slot, and an ideal transformer to model coupling to the slot. The coupling mechanism to the slots resonances and subsequent emergence of transmission gaps is explained for different positions of the microstrip line. Excellent agreement with measurement is demonstrated over the broad bandwidth of dc to 20 GHz.     

A simple and accurate model for microstrip structures with slotted ground plane

A simple and accurate circuit model for microstrip filtering structures with slotted ground plane is presented. The unit cell model consists of a series inductance and shunt capacitance for the microstrip line, an ideal transmission line characterized by its impedance and electrical length for the slot, and an ideal transformer to model coupling to the slot. The coupling mechanism to the slots resonances and subsequent emergence of transmission gaps is explained for different positions of the microstrip line. Excellent agreement with measurement is demonstrated over the broad bandwidth of dc to 20 GHz.     

地平面上方垂直磁流元电磁场的精确解析表达式

利用倍特曼（Bateman)展开公式，地平面上方垂直磁流元电磁场中的索末菲型积分被表达成快速、绝对收敛的球面波展开式；应用超几何函数的巴恩斯（Barnes)积分表达式，展开系数被表达成以复介电常数为宗量的雅可比多项式。该展开式是此类索末菲半空间问题精确解答，它能够为相关电磁场问题研究提供方便、准确的解析表达式。     

A review of bistatic k-space imaging for electromagnetic predictioncodes for scattering and antennas

A bistatic k-space imaging concept for frequency-domain (FD) electromagnetic (EM) computer codes is presented. The concept enables the computation of images without the frequency sweep required for experimental images, resulting in a significant reduction in computational effort. This analytical imaging technique uses bistatic radiation computed from a generalized radiation integral. Images permit physical insight and understanding into how a radiation or scattering pattern is produced, by decomposition of the resultant radiation into contributions from localized scattering centers, or hot spots. Knowledge of these hot spots permits a user to understand and modify the structure to obtain desired features     

A full-wave analysis of interconnection planar lines applications to structures with finite ground plane

The high integration level associated to the increase of the operating frequency of microelectronic integrated circuits create complex electromagnetic coupling in the interconnection lines which lead to mismatch and frequency dispersion. In the present paper, we propose a full-wave analysis to characterise the electromagnetic behaviour of interconnection planar lines using mixed-potential integral equations technique. The theoretical and numerical treatments of Green’s functions for the specific structures are firstly presented. The calculated results for parallel and coplanar strips are compared to the published ones. The effect of the finite ground plane on the propagation constant and the characteristic impedance is then analysed for different permittivities. The obtained theoretical and experimental results for the reflection coefficient of straight resonators confirm finally the observed effect of the finite ground plane on the frequency dispersion and the scattering characteristics.     

Implementation and parametric analysis of single and dual band planar filtering antennas for WLAN applications

Wireless Networks - Implementation and parametric analysis of single and dual band planar filtering antennas suitable for WLAN applications are described in this paper. The single band filtering...     

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.