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In this research paper, we propose a simple procedure for accurate, stable and broadband measurements of complex permittivity of low-loss dielectric samples with considerable lengths. We identify and demonstrate by numerical and analytical analyses the main ill-behaved factor that gives rise to inaccurate peaks for measurements of electrical properties of low-loss samples in the well-known Nicolson-Ross-Weir method. Without using this factor in the expressions and combining better features of the methods available in the literature, the proposed procedure allows highly accurate permittivity measurements over a broad band. We have validated the proposed method by permittivity measurements of a low-loss sample by different methods. © 2014 Taylor & Francis.

An improved fast shadowing technique fit for the calculation of electromagnetic field is proposed in this paper based on the shadowing technique of z-buffer in computer graphics. The traditional shadowing algorithm consumes too much time, for it is necessary to judge the shadowing relationship of every two facets. The proposed algorithm combining z-buffer with traditional algorithm falls into the shadowing processing using triangle facet modeling. The problem of great time consumption in shadowing judgment for electrically large targets is well solved through proper subdivision of buffer and localization of judgment within facets in the surrounding buffer elements. The proposed arithmetic has great advantages over the traditional one, especially in its high running speed. This improved technique is tested to be valid in that it remarkably increases the computation speed on the premise of satisfying the precision requirement.

The paper deals with modelling of radiation from arbitrarily shaped thin wires above a multilayer and related engineering applications. The formulation is based on the set of corresponding Pocklington integro-differential equations (IDEs) for curved wires. The influence of lower layered half-space is taken into account by means of simplified reflection coefficient stemming from modified image theory (MIT). The set of coupled IDEs is handled via Galerkin Bubnov variant of indirect boundary element method (GB-IBEM) for curvilinear elements. The related field radiated from a wire configuration is obtained from corresponding integral expressions including integration of the currents along a given wire configuration. Some illustrative computational examples for certain wire configurations pertaining to dipole antennas, power communication systems (PLC) and instrumental landing systems (ILS) are given in the paper.

This paper presents an efficient time-domain analysis of RF/microwave nonlinear circuits in the presence of the incident uniform plane wave. In this paper, a set of differential equations, includin...

As a power system turns out to be all the more heavily loaded and more unpredictable, maintaining stability becomes a difficult issue. In this paper, we propose an optimal control procedure for power system adjustment utilizing a proportional-integral-derivative (PID) controller in a coordinated power system. In modern applications, the most generally utilized controller is the PID controller, which necessitates productive techniques to control the distinctive parameters of the plant. The proposed strategy uses the particle swarm optimization algorithm-based way to deal with producing the optimal tuning parameters. This paper investigates the execution of the power system and dynamic execution of the controller is compared with the conventional controller with approval of the adequacy of the proposed mixture controller. Experimental results demonstrate that the proposed system has upgraded the system stability of the power system all the more adequately existing systems.

In part I of the present paper, we analysed helical slow-wave structures of travelling-wave tubes (TWTs) taking into account the space harmonic effects arising from the axial periodicity of helix turns as well as azimuthal periodicity of the dielectric helix-supports and metal vanes of the envelope of the structure. Here, in part II of the paper, we extended the analysis to the fast-wave regime to study a disc-loaded circular waveguide interaction structure of a gyro-TWT taking into account the space harmonic effects arising from the axial periodicity of the annular discs. Four variants of the structure were studied. Two of these variants use thin and thick metal discs, respectively. The third variant has inherently two interwoven metal disc-loaded structures, and the fourth variant has dielectric discs interposed between consecutive metal discs. We studied the effect of tapering the disc parameters and predicted the optimized parameters for the wideband and high-gain gyro-TWT performance. The ana...

This paper employs the finite-difference time-domain method (FDTD) to model and study the propagation characteristics and distribution features for extremely low frequency (ELF) in Earth-ionosphere (EI) system. For electromagnetic pulse source whose bandwidth is 10 Hz, the ELF electromagnetic wave forms standing wave. When the bandwidth is 100 Hz, there exists 180° phase reversals. Due to EI system, the electromagnetic field generated by horizontal dipole antenna is mainly vertical electric field and horizontal magnetic field when the receiver is away from the source antenna and locates on the surface of the earth. The distribution is mainly determined by the polarization direction of the source antenna other than the topographic feature and the conductivity. The ELF electromagnetic field can be used as incident field to detect conductivity anomaly underground. Thus, this paper may provide valuable information for long distance and large-scale underground detection, showing potential applications ...

This paper proposes a new hybrid method called MS-GEC/PO. This method is based on the coupling between the multi-scale combined to generalized equivalent circuit method (MS-GEC) and the hybrid approach MoM-GEC/PO (MoM-GEC method coupled to Physical Optic method). The MS-GEC method, in its new formulation based on local modal operators, can reduce considerably the requirements (CPU time and memory resources) especially when the number of scales increases. However, the MoM-GEC/PO can reduce these requirements because it is based on a single test function permitting an important reduction of the manipulated matrices size. Consequently, applying the new hybridization MS-GEC/PO, we can take the advantageous of both of these methods assuring a multiple gain in requirements. In this paper, we present the new considered hybridization and we validate it on an example of application. The obtained results are in agreement with the MoM-GEC method.

In this paper, the beam steerable isotropic Linear Antenna Array is designed for reducing the side lobe level using evolutionary optimization technique. The optimization techniques particle swarm optimization (PSO) and Novel PSO are used to reduce the side lobe level (SLL) as well as to steer the main beam in specific direction. In this design of steerable Linear arrays, the amplitude excitations are optimized. Obtained results show that the maximum peak of SLL of the resultant patterns is as per requirement. This paper presents a good performance in the array factor response and suppressed SLL for different numbers of elements and different values of the steering angle of direction of the main beam with evolutionary optimization.

In this paper, the physical model is extended for vias embedded in layered media between two parallel-plate pairs. The effect of this inhomogeneity on signal integrity analysis is crucial, but is rarely studied especially by using the equivalent circuit model. The model presented in this paper is constituted by upper and lower via-to-plane capacitances which are different from each other due to the inhomogeneous dielectrics and equivalent impedance matrix of the parallel-plate cavity with equivalent wave number. The via-to-plate capacitance with layered media is calculated by using cascaded Green’s function with image theory and integral equation method based on partial capacitance, which is the main contribution in this paper. The parallel-plate impedance is calculated by using the cavity resonator method. Transverse resonance method as well as an equivalent approximation method is used for wave number evaluation. For the first time, the circuit model presented in this paper is used for the issue of laye...

In this paper, a new approach for electromagnetic modeling of the diffraction of finite multi-dielectric thickness in metallic wave-guides is presented. The proposed model, based on the method of moments combined to the generalized equivalent circuit, can concern several applications such as the investigation of vegetation leaves properties. Hence, in this work, we are interested in studying a corn leaf which is assumed as a superposition of rectangular dielectric slabs. We develop an electromagnetic analysis of a rectangular wave-guide loaded with a dielectric model that is composed of a leaf plant with a finite thickness. Interest has been focused on the influence of the wave diffraction according to the geometrical intern of the corn leaves. In this paper, we are particularly interested in studying these parameters against the dielectrics widths and the distances separating them. To validate this work, the obtained results are compared with those previously measured and published. A good agreement with...

The method based on the dual-frequency correlation function of reflected signals is one of the effective approaches for sea wave height estimation in radar altimetry. This method, however, has been applied for relatively low-altitude flights. As shown in our early studies, for the estimation of the sea wave heights using the dual-frequency correlation function, it is necessary to synthesize the array antennas, which are perpendicular to the flight direction. In this paper, we derived the limiting accuracy of the measurement of the sea wave heights using the dual-frequency microwave interferometry, and analyzed its dependence on the sea wave heights and the radar system parameters. Evaluation of the limiting accuracy of the measurement of the sea wave heights shown in the paper verified its high accuracy for sea status monitoring using a small remote sensing spacecraft.

A metamaterial slab applied as cover in front of a patch antenna focuses the radiations from patch, reduces the beam-width, thus enhancing the Gain and Directivity. Usually the slab is placed at quarter wave distance from the patch; this paper focuses on investigating the effects of varying this distance. Also, if a dielectric is placed in between metamaterial cover and patch antenna, the effects of changing the value of dielectric constant are presented in this paper. The metamaterial under consideration is a modification of Pendry’s SRR structure, its unit cell is formed by connecting metallic traces of two-edge-coupled split ring resonators to form the infinity symbol on one side of the substrate and an array of conducting wires on the other. The unit cells were arranged to form an array and an investigation of S-parameters was done to check the negative index property. A conventional patch antenna generally shows 3 dB beam-width of ~80° and 5–6 dB gain, whereas the antenna presented in this paper with...

This paper proposes a detail analysis of a single layer, single-feed microstrip patch antenna for size reduction and multifrequency operation. An open-ended inverted L-shaped slot is introduced at the left-hand side radiating edge of the patch to reduce the size of the antenna by reducing the resonant frequency. Multiple resonant frequencies are also obtained by introducing the open-ended inverted L-shaped slot. The measured result shows that the size of the proposed antenna has been reduced by 74.3% when compared with conventional rectangular microstrip antenna with same patch area. The proposed antenna also provides increased frequency ratio (the ratio of second or higher resonant frequency to the first resonant frequency). The conventional and proposed antennas are designed and simulated by method of moment-based IE3D software. An extensive analysis of the antenna parameters (reflection coefficient, radiation pattern, gain, etc.) including surface current distribution is given in this paper.

One of the major issues in multifunction radar is the allocation of time resources to maximize the ability of the radar. If jet engine modulation (JEM) is analyzed correctly in an insufficient dwell time environment, the remaining time can be allocated for other tasks. This paper presents effective reconstruction of insufficient JEM signals based on compressed sensing (CS) method. The CS method was employed to extract a refined spectrum from insufficient JEM signals. In the process of applying the CS method to JEM signals, we utilized the modified linear programming (LP) standard form of an optimization method. The approach proposed in this paper is significant because it enables reliable estimation in spite of the insufficient JEM signal. Its application to insufficient JEM signals demonstrated that the reconstruction method presented in this paper improved the accuracy of JEM analysis and is expected to be effective from the perspective of radar resource management.

This paper presents a systematic review on the long-period fiber grating (LPFG) formed by the electric arcing method. The basic concept of LPFG and the background of the electric arcing method are thoroughly discussed. The paper also discussed on the methods to improve the sensitivity of LPFG towards external perturbations. The LPFG has been reported to have potential usage as sensor, thus a section of the paper has focused on some application of arc-induced LPFG as sensors.

Various wireless communication systems require simple and high-gain radiating element operating in different working frequency bands. In this paper, an epsilon-negative metasurface antenna (ENG-MS antenna) with high-gain and frequency-tunable properties is proposed, fabricated and studied. This antenna is composed of an original double-sided printed bow tie antenna (source antenna) and an ENG-MS frequency selecting reflection layer. The strong electric interaction between ENG-MS (allowing evanescent wave only) and source antenna exhibits a significant effect on antenna’s radiation pattern and gain. Antenna’s gain can be selectively enhanced over the source antenna’s working frequency band. It is demonstrated that the resonant frequencies of this ENG-MS antenna can be continuously tuned by changing the distance between source antenna and ENG-MS. The proposed ENG-MS antenna in this paper shows a promising result to introduce metamaterials/metasurfaces in microwave device to realize high-gain and frequency-t...

This paper proposes a novel method for the impedance measurement of balanced UHF RFID tag antennas. The traditional method used a wire balun-connected probe to measure balanced antennas. But this technique has a system error that results from the wire balun effects. This paper presents a novel method to de-embed the wire balun effects and improve the accuracy of measurement based on algorithm. Comparing with other de-embed methods, the novel method does not need the inner structure of fixture or rely on the accuracy of modelling the measurement fixture.

In this paper, we present a review of the state-of-the-art analog and digital beamformer architectures. In addition, an analytical and experimental evaluation of a novel transceiver architecture with on-site coding is conducted. The architecture features agile beam forming, jamming mitigation, and MIMO capability. The proposed architecture departs from traditional digital beamforming approaches. Specifically, a single analog to digital converter (ADC) is assigned to a group of array elements instead of having one ADC per element. To facilitate this approach, code division multiplexing is applied to each received antenna signal prior to combining them for digitization using a single ADC. In this paper, a detailed systematic evaluation of the proposed on-site coding receiver is carried out. We examine the trade-offs using non-ideal components (e.g. filters), including finite resolution ADCs and their impact on the system’s noise floor. It is concluded that the bit error rate shows minimal SNR degradation us...

This paper presents a method for predicting the maximum electric field level inside a metallic cavity making use of the quality factor (Q) estimation. This calculation requires a two-step approach combining several theoretical models which can be found in the literature. A very good agreement in the frequency range between 100 MHz and 40 GHz has been achieved with the data obtained from the validation of two reverberation chambers made of different conductive materials. The wide frequency band analyzed permits us to draw conclusions about the main contributions in the cavity Q and their relationships with the maximum electric field level. This paper also describes and identifies the relationships between the antenna parameters and dissipation mechanisms vs. frequency for the different models. This estimation could be used to calculate a possible EMC threat of a spurious emission of EM signals which could produce a susceptibility problem in other equipments installed in the same cavity.

In this paper, the specific absorption (SA) distribution in a human body, exposed to ultra-wideband (UWB) pulse, has been analyzed by taking into account the dispersion characteristics of biological tissues. The dispersive properties of biological tissues are characterized by the 4-pole Cole-Cole model. However, implementing the finite-difference time-domain (FDTD) method of the 4-pole Cole-Cole model requires many resources and the calculation time. The complicated dispersive characteristics of biological tissues create difficulties in the analysis of exposure assessment by on-body devices. Because UWB frequency band is from 3.1 to 10.6 GHz, the dispersive characteristic may be sufficient to the 1-pole Cole-Cole model. In this paper, we fitted the 4-pole Cole-Cole model by the 1-pole Cole-Cole model for the given UWB band. The fitted results are in good agreement with the 4-pole Cole-Cole model. The FDTD method with the dispersive algorithm for the 1-pole Cole-Cole model was applied using SA analysis of ...

The conservation laws for optical solitons with spatio-temporal dispersion are obtained in this paper. There are three conserved quantities that are reported in this paper. They are the power, linear momentum, and the Hamiltonian. The conserved quantities, from their respective densities, are obtained from 1-soliton solution that was reported earlier. Five types of nonlinear media are taken into account.

This paper proposes novel high isolation transmitter and receiver antennas that make use of high-impedance surfaces (HISs) for repeater applications. Both the microstrip antennas and HISs are designed to operate at a frequency of 2.05 GHz for Korean WCDMA services. The HIS proposed in this paper can effectively absorb back radiation and surface waves from each antenna, and this reduces coupling between the two antennas. Therefore, it is experimentally demonstrated that the use of HISs improves isolation by 6 and 10 dB, depending on the orientation of the two antennas.

In this paper, the alternating projection (AP) scheme is applied to get the initial and the final estimates of the Capon beamforming algorithm and the MUSIC algorithm. In a previous paper, the AP scheme has been proposed as a computationally efficient method for the initialization and optimization of the cost function for the ML-based angle of arrival (AOA) estimation problem. We call the AP scheme in the previous paper the brute-force AP strategy. To improve the brute-force AP, we suggest the Newton AP which consists of the successive one-dimensional Newton search. The brute-force AP can be used for the initialization and the optimization of the cost function of AOA estimation, and the Newton AP can be used for the optimization of the cost function for the AOA problem. We compare the performance of the AP-based approach with the conventional implementation of the AOA estimation algorithm using two-dimensional brute-force search.

This paper presents a broadband microwave non-destructive technique for characterization of carbon nanotubes (CNTs). Typically, commercially available carbon nanotubes are powder-like samples and, therefore, in this paper, a broadband characterization technique to extract electrical conductivity of powder materials is developed. The technique uses a microstrip line configuration in conjunction with a cavity resonator technique. The electrical conductivity of CNTs is extracted from the measured attenuation in the signal response (|S 21|dB) for the microstrip configuration with a signal trace made of copper and a ground plane filled with CNT samples. A resonant cylindrical cavity is also used in the measurement process to help determine a correction factor for the surface roughness of the CNT microstrip ground plane. A novel method to take attenuation due to surface roughness into account to determine conductivity of CNTs is introduced. Experimental and numerical verification of the proposed method is provi...

International audience; This paper develops an innovative model of bandpass (BP) negative group delay (NGD) inverted arm topology of parallel lines. The S-matrix model is established from impedance and admittance matrix operations of elementary transmission lines constituting the topology. Parametric analysis is performed to assess the influence of inverted arm structure sizes on the BP NGD specifications. To validate the theoretical concept, a proof of concept is designed in microstrip technology. The calculated and simulated results are in very good agreement. NGD value, center frequency and bandwidth of about -8 ns, 3.6 GHz and 4 MHz, respectively, are observed with insertion loss better than 1 dB and reflection loss better than 18 dB. The innovative NGD physical structure could be an important asset to reduce propagation delay in the upcoming telecommunications systems as the 5G system.

An analytic study on soliton amplification in inhomogeneous optical fibers is presented in this paper. By use of the Hirota method, the bilinear forms for the nonlinear Schrodinger equation, which describes the soliton propagation in inhomogeneous optical fibers, are obtained. The analytic soliton solutions are derived with symbolic computation. According to the solution obtained, the solitons are amplified without the pedestals, and the technique permit high-quality amplification of solitons, which to our knowledge has not been reported before. The physical effects affecting soliton amplification are discussed. The gain of the amplifier, the soliton velocity and phase can be adjusted with two arbitrary parameters. The influences of group-velocity dispersion and Kerr nonlinearity on soliton amplification are studied. With the different values of group-velocity dispersion and Kerr nonlinearity, amplification of solitons in inhomogeneous optical fibers can be controlled. The results of this paper p...

In this paper, an efficient method based on the sequential quadratic programming (SQP) algorithm for the pattern synthesis of concentric rings antenna arrays to reduce side lobe levels (SLL) by controlling only the amplitude excitations of each array element was presented. SQP algorithm is a deterministic method of multi-objective optimization. It is the most widely used for the resolution of nonlinear problems. It consists of transforming the nonlinear problem to sequence of quadratic sub-problems by using a quadratic approximation of the Lagrangian function. In order to illustrate the performance of the proposed method, several examples of planar concentric rings antenna array patterns with almost one-half wavelength spaced isotropic elements to reduce the SLL and to norrow the half power beam width are presented. The results shown in this paper and compared with those obtained by the application of uniform, Hamming and Blackman weighting, demonstrate the effectiveness of this optimization meth...

A tunable dual-band microstrip filter using step-impedance resonators with harmonic suppression and compact size is presented in this paper. The second passband frequency of the filter can be flexibly controlled by tuning the bias voltage across the varactor whereas the first passband frequency is fixed. The structure is composed of couple lines and capacitive-loaded stepped-impedance resonator to provide frequency tunability and folded to reduce the size of the filter. The coupling scheme applied in this paper helps to reduce insertion loss and eliminate parasitic parameters, which is due to that extra blocking capacitances that are needless compared with the conventional coupling structure. To certify the validity, a prototype dual-band filter is designed, fabricated, and measured. The measured results show good agreement with the simulated ones.

The paper deals with a direct time-domain (TD) analysis of multiple wire configurations using various TD measures based on the energy stored in the near field. The currents along the wires are obtained solving the coupled Hallen integral equations. Once the current distribution is determined it is possible to calculate the charge via continuity equation. Knowing the distribution of current and charge along the wires, TD energy measures involving spatial integrals of squared values of transient current and charge, the energy stored in the electric and magnetic fields of wires are evaluated. Then total TD power measure defined as the time derivative of the total energy measure is computed. Finally, according to the definition stemming from the circuit theory the distribution of rootmean-square (RMS) values of transient current is calculated. Some computational examples for transient current, TD energy, and power measures, respectively, and RMS distribution along the wires are presented.

A simple and compact circular planar monopole ultra-wide band antenna with a 5.8 GHz band rejection and directional radiation pattern is proposed in this paper. The split ring resonator (SRR) technique has been utilized to produce band rejection at 5.8 GHz. Some results and analysis on several SRR placements are highlighted in this paper. The parabolic ground structure is used to produce a directional radiation pattern together with bandwidth enhancement. The proposed prototype antenna has acceptable performances in terms of gain, efficiency, and directional radiation pattern. Simulated and experimental results are discussed.

We consider the performance analysis of the natural frequency-based radar target detection in the frequency domain. Two cases of the detection are considered: one is for known residues, called the likelihood ratio test (LRT), and the other is for unknown residues, called the generalized likelihood ratio test (GLRT). In time-domain detection scheme [Mooney JE, Ding Z, Riggs L. Performance analysis of a GLRT in late-time radar target detection. Prog. Electromagn. Res. 1999;24:77–96], the authors showed that the decision statistic for the LRT and the decision statistic for the GLRT are Gaussian distributed and chi-square distributed, respectively. Note that the formulation in [Mooney JE, Ding Z, Riggs L. Performance analysis of a GLRT in late-time radar target detection. Prog. Electromagn. Res. 1999;24:77–96] is for the time-domain late time response and that the formulation proposed in this paper is for the frequency response. In this paper, we consider the detection problem in the frequency domain. The sch...

Range profile (RP) is an effective one-dimensional radar signature used to recognize a target, and many research results have been published regarding the classification of RPs of targets engaged in solo flight. However, because targets fly in formation with complicated motion parameters, further study is required to identify multiple targets simultaneously. This paper presents a method of recognizing multiple targets that are flying closely spaced in a formation using separate RPs of each target. However, it is very difficult to extract RPs from each target which uses reflected signals from several aircraft in a formation at several aspect angles. In this paper, RPs of each target are separated by using the segmentation method based on the range-Doppler algorithm. Classification results from using five targets that are composed of point scatterers prove the effectiveness of the proposed method.

The influence of fabric weave type on the shielding effectiveness (SE) of electromagnetic shielding fabric (ESF) is studied in this paper. Some representative samples with different weaves are manufactured to test the SE using the waveguide testing system. The SE of each sample is obtained at different frequencies of the emission resource. Experimental results show that the yarn float which causes the aperture change of metal fiber arrangement is the key influencing factor without changing other parameters of fabric. Then, a new theory that the SE of the ESF with different weave types is determined by the number of the yarn floats in a weave repeat that is proposed. An evaluation model of the SE for the ESF with any weave type is established. By further verification, the results show that the method is satisfied and can be a basis for the evaluation of SE of the ESF with different weave types when other structural parameters of the fabric are not changed. The variation revealed in this paper can provide a...

To solve the negative effect of the traditional detection probability model of infrared (IR) imaging system under complicated backgrounds, a novel model valid for various backgrounds is proposed. Based on the operating distance model of the IR imaging system, this paper analyzes the relationship among detection probability, signal-to-noise ratio, and operating distance. Meanwhile, traditional detection probability model for point target under a unitary background is derived. Then, this paper deduces the new model under a complicated background by introducing the idea of probability distribution. To get the IR radiance of complicated background which is the key information in the new model, the Radiance–Gray function is introduced. Finally, two detection probability calculation instances show that the new model can accurately evaluate the detection probability under complicated backgrounds.

This paper presents application of a novel cylindrical ferrite coupled line (CFCL) junction to integrated nonreciprocal devices. In such a junction, high gyromagnetic coupling occurs. This gives possibility to design a Faraday rotation CFCL junction with the ferrite rod having shorter length and lower saturation magnetization than the planar structures commonly known in literature. By utilizing the proposed cylindrical junction in integrated nonreciprocal devices, it is possible to reduce not only their dimensions but also the insertion losses occurring in such structures. In this paper, we present an application of CFCL junction to integrated isolator. The results of numerical simulations are verified experimentally, and good agreement is observed.

A generalized formulation of Cauchy method for multiplexer rational model extraction is presented in this paper. This new technique can extract the multiplexer rational models from either measurement or electromagnetic simulation results. The generalized formulation of Cauchy method takes into account the relationship between the transmission coefficients and reflection coefficients of each channel filter. It is suitable for multiplexers whose channel filters are connected through resonating junction. The total least square method is applied to solve the system matrix. The new technique presented in this paper is suitable for lossless case as well as lossy case and is verified by lossless triplexer and circuit simulation lossy triplexer examples successfully.

A Multi-Input Multi-Output (MIMO) Synthetic Aperture Radar (SAR) system has been considered for its potential to simultaneously improve the performance of stationary scene imaging and ground moving target indication (GMTI) by utilizing multiple subarrays both at transmission and reception. To successfully exploit the potential benefits of MIMO SAR for practical imaging application, a signal model for MIMO SAR system with colocated arrays is presented in this paper, then we propose a novel procedure for imaging processing by coherently combining the returns from multiple receive subarrays. Our approach can make efficient use of the transmitted waveform power, and resulting in higher Signal-to-Noise Ratio (SNR) images. The effectiveness of model and MIMO SAR imaging method proposed in this paper are demonstrated by simulation experiments.

A simple ultra-wideband planar rectangular printed monopole antenna with dual narrow band-notched characteristics is presented in this paper. Dual narrow band-notched frequencies at 3.4 GHz and 5.2 GHz are achieved by embedding a U-shaped slot in the radiation patch and a small pentagon patch on the ground, respectively. Moreover, input impedance, conceptual equivalent circuit models and surface current distributions are built for analysis and explanation of dual narrow band-notched characteristics. At the same time, an approximate expression of the notched frequency with the pentagon patch dimension is proposed in this paper. The designed antenna operates over the frequency band between 2.69 GHz and 12 GHz (126.8%), with one narrow notched band from 3.32 GHz to 3.55 GHz (6.7%) and the other from 5.04 GHz to 5.39 GHz (6.8%). The antenna is successfully simulated, fabricated and measured, showing broadband matched impedance, dual narrow band-notched characteristics, stable gain, high radiation efficiency a...

In this paper, the efficiency analysis of a mid-range wireless energy transfer system is performed through non-resonant magnetic coupling. It is shown that the self-resistance of the coils and the mutual inductance are critical in achieving a high efficiency, which is indicated by our theoretical formulation and verified in our experiments. It is experimentally shown that high efficiency, up to 65%, can be realized even in a non-resonant wireless energy system which employs a device part with moderate or low quality factor. We also address some aspects of a practical wireless energy transfer system and show that careful design of the de-tuned system can intrinsically minimize the power dissipated in the source part. Our non-resonant scheme presented in this paper allows flexible design and fabrication of a wireless energy transfer systems with transfer distance being several times of the coils' radius.

Coupled volume-surface integral equation (CVSIE) and non-coupled volume-surface integral equation (NCVSIE) are compared in this paper. For scattering problems, results with similar accuracy are given. For the radiation problems, different impedance behaviors are arrived using the two approaches, by comparing the numerical results to the results from measurement or reference papers. The CVSIE approach has better performances in the input impedance calculation.

An efficient mutual coupling reduction method is introduced in this paper for an extremely closely-spaced dual-element microstrip antennas positioned on a finite sized ground plane for MIMO application at 5.8 GHz. High isolation can be achieved through a simple transmission connection line (TNL) between the microstrip antennas. The position, length, and line width of the transmission connection line need optimize designing to maximize the isolation. It is found that isolations of more than 48 dB can be achieved between two parallel microstrip antennas sharing a common ground plane, with inter-antenna spacing of 0.038λ 0 and ground plane size 0.85λ 0 × 0.735λ 0. All along this paper, several prototypes are fabricated and their performances measured to validate the obtained IE3D moment method-based simulation results.

A precise recognition method of missile warhead and decoy in multi-target scene is presented in this paper. In multi-target scene, the echoes received by radar are the mixture of backscattered signals from all targets within radar beam. In order to separate backscattered signal of each target by Independent Components Analysis (ICA) method, a radar system of multiple antennas with different patterns is designed in this paper. Having a high precision of separation, the complex ICA method is used to decompose independent signals from the linearly mixed echoes received by antennas, instead of using real 2D-ICA to decompose independent Time Frequency (TF) images from TF images of these mixed echoes. The dynamic feature of each target can then be identified by extracting and analyzing the Doppler tracks of decomposed backscattered signals. To obtain high accurate simulation results, the backscattered signals are simulated by electromagnetic full-wave numerical method. The simulation and post processing results...

In this paper, a novel miniature dual-mode bandpass filter based on modified Sierpinski fractal is proposed and realized on the ultra thin (100 μm) flexible liquid-crystal-polymer (LCP) substrate for wireless local area network (WLAN) IEEE 802.11a. The subwavelength property which leads to the miniature characteristic is investigated in this paper. We adopt the 3rd order Sierpinski geometry as the mainly dual-mode resonator to form a dual-mode filter. The measured result is in good agreement with the full-wave simulation result.

In this paper, a novel serrated structure at the edges of the antipodal Vivaldi antenna is introduced. Compared with the Vivaldi antenna without serrated structure, the novel structure antenna has a better Front-to-Back ratio (F/B ratio). Additionally, when building a 4-element array with mirror image elements placed alternately along the H plane, the cross-polarization level at the boresight is reduced a lot compared to conventional array configuration. The design of the novel 4-element Vivaldi antenna array with mirror image elements described in this paper experimentally produces a gain with a range of 9∼15 dBi, F/B ratio more than 15 dB, and cross-polarization level at the boresight is reduced more than 10 dB from 3.5 GHz to more than 10.6 GHz with –10 dB return loss. The novel antenna array can be used for directional UWB systems.

In this paper, we present a calibration procedure for radar cross section (RCS) measurement systems that is insensitive to environmental perturbations. This procedure has been used in several measurement campaigns to calibrate the measurement system of the Spanish Navy called LIBRA. The proposed method not only allows us to discard environment corrupted measurements but also to make use of them thanks to the Doppler discrimination. A bank of Doppler filters, together with the dynamic control of the calibration target, allow us to turn our traditional calibration procedure into a free-space calibration method, avoiding the influence of any possible multipath component that could be present in the time of calibration. The paper contains a detailed description of the proposed procedure. Also, some application examples that confirm the usefulness and accuracy of this technique are presented.

Radio-frequency identification (RFID) blind spots are the regions within the maximum operating range of the RFID system where the RFID reader fails to read the RFID tag. The existence of blind spots have troubled supply chain management and RFID system engineers because any failed or omitted reading of RFID tag would slow down the inventory tracking process. This paper studies the potential locations of blind spots as well as the effectiveness of several blind spots remedy methods such as frequency diversity, spatial diversity, polarization diversity, and antenna beam steering. Using the blind spots creation approach introduced in this paper, the locations of the blind spots can be calculated and visualized. From our simulation results, spatial diversity and polarization diversity are found to be better than all other aforementioned approaches.

The first aim of this paper is to make the connection between complex source method (CSM) and Plane Wave Spectrum (PWS) clear. As a consequence, the paper also presents the PWS of 2D complex beams which completes the description of these solutions. This fact allows us to give straightforward relations between beam parameters and spatial confinement in order to know how to model a typical laser beam as a complex beam, which is a desirable fact since such a solution fulfills the wave equation instead of the paraxial wave equation as typical Gaussian beams do.

A novel dual band-notched monopole ultra-wideband (UWB) antenna which is composed of a radiation element, a ground patch and several tuning stubs is proposed. The antenna with compact size of 20 mm × 31.5 mm works in the band of 3.1 ∼ 10.6 GHz with voltage standing wave ratio (VSWR) below 2, except the bands of 3.3–3.8 GHz for WIMAX and 5.1–5.8 GHz for WLAN. By changing the lengths of the tuning stubs, the central frequencies of the dual notched bands can be adjusted easily, which is discussed in the paper. The results are given in this paper and show a acceptable agreement between the simulation and measurement.

A novel double-printed U-shaped dipole antenna with a band-notched function suitable for UWB application is presented and investigated in this paper. The band-notched characteristic is achieved by connecting L-shaped strips to the antenna rather than inserting slot to the antenna. Compared with cutting slot on the antenna, the method of connecting L-shaped strips is more suitable for the U-shaped dipole antenna because of the limited space to locate the slot. The measured results show that the frequency band of VSWR < 2 covers 3.1 to 10.6 GHz UWB band, while the notched frequency range is 5.10–5.88 GHz which covers 5 GHz WLAN band of 5.15–5.825 GHz. Transfer function and time domain characteristics are also studied in this paper.