Feature extraction is a challenging problem in radar target identification. In this paper we attempt to exploit the sparse property of the scattering signature with a undercomplete dictionary for target identification, and establish a feature extraction scheme based on the undercomplete dictionary. Furthermore, as an application, we present a feature vector, named as the atom dictionary feature, which is extracted from the scattering signatures over a wide-angle sector. Numerical simulation results show that the proposed atom dictionary feature can improve the performance of radar target identification due to the exploitation of the sparse property of the scattering signature.

In this paper, we study in detail the electromagnetic field excited by a horizontal electric dipole in the presence of a four-layered region, which consists of a perfect conductor, the two dielectric layers, and air above. From the derivations and analysis, it is seen that the electromagnetic field includes four wave modes: Direct wave, ideal reflected wave, trapped surface wave, and lateral wave. The wave numbers of the trapped surface wave, which are determined by the residues of the poles, are between the wave number k₀ in the air and k₂ in the lower dielectric layer. The lateral waves with the wave number being k₀ are determined by the integrations along the branch cuts. It should be pointed out that both the trapped surface wave and lateral wave can be separated into the electric-type terms and magnetic-type terms. Analysis and computations show that the trapped surface waves play major roles at large propagation distance when both the dipole point and the observation point are on or close to the air-dielectric boundary.

Passive UHF RFID tag consists of a microchip attached directly to an antenna. Proper impedance match between the antenna and the chip is crucial in RFID tag design. It directly influences RFID system performance characteristics such as the range of a tag. It is known that an RFID microchip is a nonlinear load whose complex impedance in each state varies with the frequency and the input power. This paper illustrates a proper calculation of the tag power reflection coefficient for maximum power transfer by taking into account of the changing chip impedance versus frequency.

In this paper, the power dissipated through different loss mechanisms including dielectric, conductor and radiation loss is calculated for the substrate integrated waveguide (SIW) and modified substrate integrated waveguide (MSIW). The applied computational method being appropriate for structures with periodic conducting parts allows one to calculate the integrals corresponding to these powers analytically and with high accuracy.

In this paper we have reported soliton solution of one dimensional modified complex Ginzburg Landau equation. The parametric region where such soliton solution is possible is also identified.

This paper reports the miniaturization of a microstrip Wilkinson power divider by substituting the quarter wave transmission lines employed in conventional Wilkinson power dividers with its equal circuit consisting of two stubs and an inductor. Reduction of the device length to 53% its size are reported here. This Wilkinson power divider is designed at 2140MHz for using in 3G-UMTS receivers. Furthermore, the second harmonic suppression is realized in this configuration and its frequency response is similar to low pass filters because of inductor. Also, the dividing procedure, the reflection coefficient and the isolation are as good as conventional Wilkinson.

A new deembedding method in permittivity measurement of ferroelectric thin film material is proposed in this paper. By measuring the two scattering matrixes of the two samples with different length, the propagation constant of the actual network under test (ANUT) can be obtained. Further more, the permittivity would be extracted. The results show that though the proposed deembedding method, the error induced by embedding can be eliminated successfully and the propagation constant of the ANUT can be extracted accurately.

The canonical problem of an extra-ordinary Transverse Electromagnetic wave propagating in a parallel plane waveguide with a semi-infinite upper conductor and loaded with magnetized plasma is considered. The homogeneous biasing constant magnetic field is assumed parallel to the substrate and normal to the wave propagation, which incidents normally on the truncated edge. The Wiener-Hopf technique is employed and the corresponding equations are formulated for the open-radiating structure as well as for a closed one resulting from the placement of a metallic shield parallel to the waveguide planes. Closed form field expressions are obtained for the shielded geometry, while the open geometry Kernel factorization is left for future extensions. Important non-reciprocal wave propagation phenomena are involved, which lend non-even function properties to the involved Kernels. Hence, their factorization becomes non-trivial requiring new mathematical approaches. Finally, a review of the involved non-reciprocal and/or unidirectional surface waves is given, which is related to the involved mathematical complexities.

In this paper the phase centre of a pure mode, smooth wall, conical horn is studied. The method employed uses phase information obtained by aperture integration of the phase corrected mode field but differs from earlier presentations in first reducing the radiation integrals in terms of an identified family of functions prior to integration. The result is formulas for the principal plane radiation patterns that better exemplify operation of the antenna. The procedure uses these formulas together with least squares minimization to determine a best fit phase centre for each principal plane. It is shown that contrary to published results, even in its principal planes, there is no unique phase centre that is a property of the horn alone. The use of such a horn as the feed element of a radio-optical antenna system is then considered. It is shown that in situations where cost is paramount and the well known drawbacks of its unequal principal plane beamwidths and the diminished gain that results from lackof a uniquely defined phase centre can be tolerated, perhaps contrary to conventional wisdom, the pure mode, smooth wall, conical horn does have a useful role to play. This is illustrated by a design example in which such a horn was used to feed a 6.4 m. dish working in X-band with a Gregorian feed system. The result is confirmation of the usefulness of the method presented here for location of a best fit phase centre.

The general image relations of electromagnetic sources are presented around a conductor sphere. The general transformations of trigonometric functions and the unit vectors between two coordinates depart from a distance are obtained. The second scattering field for a target is derived in detail. The complex scattering field and the complex RCS are gained respectively. Results show that the electromagnetic interaction of the targets must be calculated as the distance between two targets is small. The second scattering field is small to three order in magnitude to its first scattering field as the distance becomes large. The phase shift of the second field is mainly determined by the target size and the observing position and not affected greatly by its surrounding target and the distance apart. The distortion of a pulse wave is mainly induced by the phase shift of the second scattering field from the particles as the wave propagating through the random discrete medium.

Ray tracing is of great use for computational electromagnetics, such as the well-known shooting and bouncing ray (SBR) method. In this paper, the kd-tree data structure, coupled with the mailbox technique, is proposed to accelerate the ray tracing in the SBR. The kd-tree is highly effective in handling the irregularly distribution of patches of the target, while the repeatedly intersection tests between the ray and the patch when using space division acceleration structures can be eliminated through the mailbox technique. Numerical results show excellent agreement with the measured data and the exact solution, and demonstrate that the kd-tree as well as the mailbox technique can greatly reduce the computation time.

Water bolus is used in microwave hyperthermia of cancer treatment to control the body surface temperature. In this paper the effect of water bolus on SAR distribution is investigated in the muscle layer of a three layered tissue model. Both the SAR penetration depth and the effective field size (EFS) are computed and compared in presence and in absence of the water bolus. Results are provided for distilled and fresh water with three different thicknesses of water bolus. All numerical simulations are performed using the Ansoft HFSS software. Numerical simulation results are in good agreement with published results.

This paper presents a new enhancement technique for infrared images. This technique combines the benefits of homomorphic image processing and the additive wavelet transform. The idea behind this technique is based on decomposing the image into subbands in an additive fashion using the additive wavelet transform. This transform gives the image as an addition of subbands of the same resolution. The homomorphic processing is performed on each subband, separately. It is known that the homomorphic processing on images is performed in the log domain which transforms the image into illumination and reflectance components. Enhancement of the reflectance reinforces details in the image. So, applying this process in each subband enhances the details of the image in each subband. Finally, an inverse additive wavelet transform is performed on the homomorphic enhanced subbands to get an infrared image with better visual details.

Compared with the worst-case optimization-based approach, the probability-constrained approach is a more flexible one to robust adaptive beamforming. In this paper, a precise relationship between the two approaches is built in the case of Gaussian steering vector mismatch, which shows that the probability-constrained beamformer design can be interpreted in terms of the worst-case beamformer design. Numerical simulations demonstrate that the precise version of the probability-constrained beamformer is more robust to the steering vector mismatch than the other popular robust adaptive beamformers.

On the base of the binary search algorithm of backtracking, an enhanced binary anti-collision search algorithm for radio frequency identification (RFID) system is presented in this paper. With the method of transferring the collision bit in place of the ID of the tag, the proposed algorithm can improve identification efficiency significantly. Mathematical simulation result shows that compared with the binary search algorithm, dynamic binary search algorithm and the binary search algorithm of backtracking, the proposed algorithm outperforms the three algorithms previous when handling multiple RFID tags simultaneously.

A fast and accurate near-field-far-field transformation technique with helicoidal scanning is proposed in this paper. It is tailored for elongated antennas, since a prolate ellipsoid instead of a sphere is considered as surface enclosing the antenna under test. Such an ellipsoidal modelling allows one to consider measurement cylinders with a diameter smaller than the antenna height, thus reducing the error related to the truncation of the scanning surface. Moreover, it is quite general, containing the spherical modelling as particular case, and allows a significant reduction of the number of the required nearfield data when dealing with elongated antennas. Numerical tests are reported for demonstrating the accuracy of the far-field reconstruction process and its stability with respect to random errors affecting the data.

Wireless channel identification and equalization is one of the most challenging tasks because broadcast channels are often subject to frequency selective, time varying fading and there are several bandwidth limitations. Furthermore, each receiver channel has vastly different types of channel characteristics and signals to noise ratio. Here in this paper we consider channel equalization and estimation problem from trans-receiver perspective, specifically we try to estimate blind equalization schemes particularly using constant modulus Algorithm (CMA). We try to estimate a linear channel model driven by a QAM source and adapt a FSE (T/2) using CMA. It has been shown CMA-FSE successfully reduces the cluster variance so that transfer to a decision directed mode is possible and simultaneously error is reduced.

active phased array antenna has been developed that is capable of wide scanning angle with small deviation in antenna gain using printed dipole antennas with parasitic element, which may have the capability of adjusting the influence of mutual coupling in the array element pattern. The design of the parasitic element is examined and the effect of its shape on pattern characteristics is confirmed. Beam scanning angles of 58 degrees in the φ= 0^。 plane were obtained for each array antenna pattern.

New electromagnetically coupling fed low profile broadband high gain E-shaped microstrip antennas (MSA) were proposed for high speed wireless networks in IEEE 802.11 a and j standards. The proposed antenna uses an E-shaped microstrip patch covered by a radome and fed by an electromagnetically coupled strip. To validate this concept, a single antenna element and a sub-array were designed, built and measured. The measured results indicate that the element and the sub-array cover the band from 4.8 to 6.0 GHz (return loss < −10 dB) and produce a gain of 8 dBi and 11 dBi, respectively. The developed prototypes may find their applications in wireless communication networks as mobile or base antennas.

The problem of electromagnetic scattering by 3D dielectric bodies is formulated in terms of a weak-form volume integral equation. Applying Galerkin's method with rooftop functions as basis and testing functions,the integral equation can be usually solved by Krylov-subspace fast Fourier transform (FFT) iterative methods. In this paper,the generalized minimum residual (GMRES)-FFT method is used to solve this integral equation,and several adaptive acceleration techniques are proposed to improve the convergence rate of the GMRES-FFT method. On several electromagnetic scattering problems,the performance of these adaptively accelerated GMRESFFT methods are thoroughly analyzed and compared.