When an antenna transmits a short pulse of energy such as used for ultra-wide band applications, the pulse gets distorted upon transmission. To examine the properties of pulse transmission it is helpful to analyze the system in the time domain versus the frequency domain. Presented is a spoke top antenna for transient radiation. The spokes reduce the reflection from the open end of the antenna significantly reducing the trailing pulses commonly seen in the time domain. Comparisons are made with a dipole antenna. Both analytical, modeled and experimental results are presented.

In this paper, a novel modified Wilkinson power divider without transmission line stubs (such as short-circuit stubs and open-circuit stubs) and reactive components (such as isolation inductor L and capacitor C) is developed for dual-band applications. This symmetric power divider consists of six sections of transmission lines and an isolation resistor, and the corresponding nonlinear design equations are derived by using the even- and odd-mode analysis. Moreover, by solving the final nonlinear design equations, accurate numerical design data along with different frequency ratios are obtained, and the effective normalized parameters are given simultaneously in the figure and table formats for specific applications. To theoretically verify the design parameters, an ideal equal power divider operating at both 900 MHz and 5.85 GHz is simulated. Finally, the proposed structure and design method are validated by simulated and experimental results of a typical microstrip planar power divider operating at both 1 GHz and 3.5 GHz.

This paper obtains the exact 1-soliton solution of the complex Ginzburg-Landau equation with power law nonlinearity that governs the propagation of solitons through nonlinear optical fibers. The technique that is used to carry out the integration ofthis eqyuation is He's semi-inverse variational principle.

A new high gain wideband L-probe fed inverted EE-H shaped slotted (LEE-H) microstrip patch antenna is presented in this paper. The design adopts contemporary techniques; L-probe feeding, inverted patch structure with air-filled dielectric, and EE-H shaped patch. The integration of these techniques leads to a new patch antenna with a low profile as well as useful operational features, as the broadband and high gain. The measured result showed satisfactory performance with achievable impedance bandwidth of 21.15% at 10 dB return loss (VSWR ≤ 2) and a maximum gain of 9.5 dBi. The antenna exhibits stable radiation pattern in the entire operating band.

We show theoretically that the absorption of one dimensional metal-organic periodic structure (1D MOPS) can be enhanced due to organic constituents. We have used simple transfer matrix method to calculate the absorption, transmittance and reflectance of the 1D MOPS systems. The absorption, transmittance and reflectance of 1D MOPS containing periodic of Ag/N,N'-bis-(1-naphthyl)-N,N'diphenyl-1,1'biphenyl-4,4'diamine (NPB) structure are calculated taking optical constant of NPB [1] and Ag [2]. The enhanced absorption of the considered structure is obtained in the visible and in the near infrared regions. Besides this we have also studied the absorption, transmittance and reflectance of the 1D MOPS with air and glass substrates. We find that the absorption is enhanced with variation of thickness of organic layer (NPB). Such absorption enhancement in 1D MOPS could allow many potential applications in photo-thermal technology, thermo photo-voltaic and blackbody emission.

A closed form solution is here proposed for evaluating the field diffracted by the edge of a lossless, isotropic and homogeneous double-negative metamaterial slab when illuminated by a plane wave at skew incidence. It is obtained by considering a Physical Optics approximation of the electric and magnetic equivalent surface currents in the radiation integral and by performing a uniform asymptotic evaluation of this last. The final expression is given in terms of the Geometrical Optics response of the structure and the standard transition function of the Uniform Geometrical Theory of Diffraction, so that it results easy to handle and simple to implement in a computer code. As demonstrated by numerical tests, it allows one to compensate the discontinuities of the Geometrical Optics field at the reflection and incidence shadow boundaries. Moreover, the accuracy of the solution is well assessed by means of comparisons with a commercial tool based on Finite Element Method.

In this work, the dyadic Green functions for different parts of a coaxial tubular filter are derived. Using the obtained data, it is possible to consider the circuit model of a coaxial tubular filter. Moreover, the reactance due to the discontinuity of the matching section (dielectric loaded part) is calculated.

A propagation model is presented in this paper for predicting the field strength in microcellular environments. According to the Geometrical Theory of Diffraction, the total field at a given observation point is calculated by summing the Geometrical Optics contributions and the field diffracted by the edges of each structure. The diffraction contributions are here evaluated by means of a Uniform Asymptotic Physical Optics solution to the corresponding canonical problem. Such a solution, expressed in terms of the standard transition function of the Uniform Theory of Diffraction, has resulted to be able to compensate the Geometrical Optics discontinuities at the shadow boundaries. In this framework, the structures are treated as constituted by lossy dielectric materials assumed to be non penetrable. The effectiveness of the here proposed model has been tested in some typical scenarios by means of comparisons with the Finite Difference Time Domain method.

In this paper, ultra-wideband and miniaturization, technique for the microstrip monopole patch antenna (MMPA) in wireless applications is presented. Ultra-wideband was achieved by using Printed modified ground plane on a dielectric substrate with 50­ microstrip feed line. This technique allows the bandwidth of the MMPA to be ultra-wideband with satisfactory radiation properties and reduce the antenna size. The proposed antenna with modified ground plane provides an mpedance bandwidth (S₁₁ < -10 dB) more than 5.5 GHz corresponding to 116% of fundamental resonant frequency with reduction in antenna size by 20% from original size. For further improvement in antenna characteristics, electromagnetic band-gap (EBG) structure is used. The surface wave was suppressed so the antenna bandwidth was increased to be 3--11 GHz corresponding to 170%, and the antenna size was reduced 43% of its original size. Two types of EBG are used. Holes are drilled around the patch, and embedded circular patches of the electromagnetic band-gap structure with suitable dimension are used. Details of the proposed antenna design have been described, and the typical experimental results are presented and discussed. Commercial software high frequency structure simulator (HFSS^®) version 11 was used for the antenna design.

For the inverse synthetic aperture radar (ISAR) imaging of a target at a long range, range alignment using the existing polynomial method brings about poor results because the flight trajectory changes depending on the initial position, and the motion parameters, meaning the polynomial cannot fit the trajectory. This paper proposes an improved range alignment method that models the trajectory using a combination of a polynomial and Gaussian basis functions. Initial parameters of the polynomial and Gaussian basis functions are determined by fitting the proposed model to the center of mass curve of the range profile history using the least square curve-fitting algorithm, and the optimum value is found using particle swarm optimization. This method is computationally more efficient and preserves the image quality.

We have proposed a simple waveguide method for complex permittivity determination of dielectric materials which are not completely filling the entire sample holder. The method reconstructs the permittivity from measured reflection-only scattering parameters by a one-port vector network analyzer of two configurations of the sample holder. It not only eliminates the necessity of any knowledge of the location of the shifted sample inside its holder but also decreases measurement errors occurring with the presence of undesired air gaps, which seriously affect the measurement accuracy of transmission-only measurements, present between the sample and holder walls. Furthermore, the reconstruction of permittivity can be realized by any one-port vector network analyzer, which is less expensive than their two-port counterparts. Therefore, the proposed method is cost-effective. We have analyzed the accuracy of the proposed method and noted a good compromise between the reference data and measured values of permittivities of low-loss polyvinyl-chloride and polytetrafluoro−ethylene samples (less than 8 percent for dielectric constant and less than 15 percent for loss tangent values).

This paper presents a basic analysis about the results of experiments using planar coils inner to ring coils, when planar coil is applied to a square wave voltage. In this study an uncommon phenomenon occurs in the ring coil, which is analyzed.

In this paper, we present an innovative method of cross-polarisation suppression by forming the antennas in a so called Clover Array (CA). Such structure enables usage of polarisation diversity even for UWB systems. The simplified theoretical model of operation is presented as well as exemplary results of crosspolarisation patterns. The theory was verified for CA of planar Volcano-Smoke antennas. For fabricated array the cross-polarisation in main beam is below -14 dBi in the whole FCC-UWB frequency range (3.1 GHz - 10.6 GHz).

Miter bend mirror has been designed for microwave transmission between two corrugated waveguides of the same size by iterative phase correction method. Geometrical Optics (GO) approximation has been used in our design at a frequency of 110 GHz. The equivalence principle is also adopted to forward-propagate and backward-propagate the beam onto the miter-bend mirror. The designed miter bend mirror shows a coupling coefficient up to 99.619%, much better than that of a flat mirror. The convergence rate shows that the design is very efficient with only a few iterations required.

An internal shorted patch antenna integrated with a RF/battery shielding metal case for application in a UMTS mobile phone is presented. The shorted patch antenna is mounted at the dented portion of the shielding metal case, with the top patch flushed with the top surface of the shielding metal case. This configuration shows no protruded portions, which makes the antenna very suitable to be integrated in a UMTS mobile phone as an internal antenna. With the integrated design, which provides a coupling-free region for the nearby electronic components or conducting elements in the mobile phone, possible coupling between the antenna and associated components can be avoided. Details of the proposed design showing a wide bandwidth for UMTS (Universal Mobile Telecommunication System, 1920 ~ 2170 MHz) operation are demonstrated, and effects of the dimensions of the RF/battery shielding metal case are presented and discussed.

A Sub Harmonically Pumped (SHP) mixer suitable for direct conversion receiver in 3G mobile frequency band is presented. This mixer is realized with N anti-parallel diode pairs (APDPs) and designed in self-biased structure to obtain minimum noise figure and conversion loss. In this paper, a simultaneous signal and noise analysis CAD routine to analyze a circuit consists of Arbitrary Number of anti-parallel diode pairs in self-biased structure is proposed. Then the results of this CAD routine are confirmed with other method. The mixer is optimized to obtain a maximally flat conversion gain and minimum Noise Figure over various LO powers. The proposed CAD is used to obtain the optimum number of APDPs. Also the optimum self-biased resistance and output load are calculated.

A novel circuit structure of dual-band bandstop filters is proposed in this paper. This structure comprises two shunt-connected tri-section stepped impedance resonators with a transmission line in between. Theoretical analysis and design procedures are described. The derived synthesis equations have two degrees of freedom which provide more design flexibility in filter synthesis. Notably, three advantages of the proposed filter structure lie in the fact of its increased nonuniform impedances, resulting in a compact size, wide range of realizable frequency ratio, and more realizable impedances. Three experimental dual-band bandstop filters with various frequency ratios were fabricated to demonstrate the feasibility of the new filter structure.

Based on swept frequency RCS measurements system, foam column and proper data processing procedure, the resonance curves of conducting spheres with RCS below -32.95 dBsm are achieved in a single reflector Compact Antenna Test Range (CATR), with measurement errors within 1.0 dB over most of the measurement frequencies. Nine spheres down to -49.01 dBsm are clearly imaged with Range-Doppler (R-D) method and pointwise vector background subtraction technique.

The resonant characteristic of frequency selective surfaces (FSSs) on in-plane biased ferrite substrates for the TE polarization is described. An approximate formula for evaluating the resonant frequency is presented. The tunable property of the resonant frequency of a dipole FSS is firstly demonstrated by the results obtained from the moment method (MM) and the waveguide simulator measurement. Then the approximate formula is validated by the MM as well as measured results already published in a previous paper. It is interesting to note that two separate resonances occur at any magnetic bias field, and both increase as the magnetic bias field increases. The fractional tuning range is investigated based on the approximate formula. The results show that it increases as the saturation magnetization increases and decreases as the center frequency increases.

Phase unwrapping is a key problem to generate digital elevation maps (DEMs) by synthetic aperture radar (SAR) interferometry. A lot of phase unwrapping algorithms have been proposed to solve this problem. However, in noisy region, many unwrapping algorithms are inoperative because of the denseness of residues. In this paper, we propose a path following phase unwrapping method, namely Residue-Pairing (RP) algorithm. The algorithm starts from residues, based on the aggregate of coordinates of each positive residues (or negative residues), to search the nearest opposite polar residue and connect them. Compared to the Goldstein's algorithm, the brunch cuts produced by this algorithm can effectively decrease their total length and contract the isolated region especially in noisy region. With raw data simulation, the results confirm the validity of RP algorithm in dense-residues region.