To investigate the effect of forest spatial structure on SAR interferometry (InSAR) data requires an electromagnetic scattering model capable of expressing radar observation in terms of parameters describing forest spatial structure. In this paper, we propose an electromagnetic scattering model for mixed-species forest which includes the coherent effect of forest structure and preserves phase information of radar backscattering signal. Interferometric SAR images of three-dimensional (3-D) scenes are simulated based on this model and the heights of scattering phase centers are estimated from the simulated InSAR data. The results show that the model is suitable for simulating interferometric SAR response to forest canopies and for investigating the forest spatial structure. We also compare the backscattering coefficients predicted by the proposed electromagnetic scattering model with the JERS-1 L-band SAR and ENVISAT ASAR C-band data acquired at forest stands of Changqing test site in Daxinganling, Northern China. Good agreements are obtained between the model results and measurement data.

In this paper, a folded substrate integrated waveguide (FSIW) cavity is analyzed theoretically. Formulae for the determination of the dimensions of the FSIW cavity have been deduced. To verify the proposed formulae, simulated results are compared with the results of the formulae and good agreement has been observed between them. An example filter working at 8 GHz is designed and fabricated. Good agreement between the simulated and the measured results has been obtained. Result shows the advantage of wide out-of-band rejection and compact size.

The full MIMO radar and the partial MIMO one are introduced. The performance analysis of beamforming for MIMO (Multiple-input Multiple-output) radar and comparisons with the phased-array radar are given. The expressions of beamwidth, gain loss and detection range for MIMO radar are derived. Theoretical analysis and simulations show that the beam of the full MIMO utilizing all virtual array elements is identical to the two-way beam of the phasedarray radar, and that the beam of the partial MIMO selecting elements with different phase centers (phase shifts) is narrower, but has a gain loss. Additionally, the partial MIMO can avoid aliasing in space when the transmitting antennas are spaced at greater than half-wavelength spacing. As scanning radar, the partial MIMO radar has smaller detection range than the phased-array radar, and the full MIMO radar has the same range as the phased-array radar.

The measurement of inhomogeneity and irregularity of dielectric plate requires metering equipments with high spatial resolution power and contactless method. As we know, a measurement system with thin beam has high spatial resolution power. In this paper, a beam compressed system (BCS) is proposed to improve the spatial resolution power for measuring inhomogeneity and irregularity of dielectric plate at millimeter wave band. The beam shape of the BCS has to be carefully designed to achieve a very thin shape which has to be constant over a long range. The BCS can be applied to detect inhomogeneity and irregularity of a dielectric plate from cell to cell with its thin beam. Simulations with FDTD and FEM and experiments are carried out to confirm the performance of the designed BCS, both simulation and experimental results have good agreement. And the images of the permittivity or thickness variance of dielectric plate are given to demonstrate the advantages of the BCS over traditional Gaussian beam measuring method.

This paper presents a compact dual-band slot antenna for 2.4/5 GHz WLAN applications. The radiating elements of the proposed antenna are composed of a square ring slot and a circular ring slot, operating at 2.4 GHz and 5 GHz bands respectively. The antenna size is very compact (40mm × 40mm × 1mm), and can be integrated easily with other RF front-end circuits. It is demonstrated that the proposed antenna can completely cover the required bandwidths of IEEE 802.11b/g (2.4-2.485 GHz) and IEEE 802.11a (5.15-5.825 GHz) with satisfactory radiation characteristics. Good agreement is achieved between the simulated and measured results.

The sensitivity of cylindrical and spherical transformation cloak to several factors has been carefully studied in this paper. We find that the performance of the transformation cloak is quite sensitive to the crevice in the shell. When an obstacle is not completely wrapped inside the cloaking shell,noticeable scattering will be induced outside. It is also shown that if the shape of the cloak is changed in certain ways while the material parameters remain the same,the backward scattering is still zero. In addition,the combination of parts of cylindrical cloak can only achieve perfect invisibility in one direction,while combining the cylindrical cloak with two halves of spherical cloak can still make a perfect 3-dimensional (3D) invisible cloak. The findings are verified with finite element based simulations as well as theoretical calculations. Our discussion results are valuable to the implementation of cloak in engineering.

A novel compact dual-band electromagnetic band-gap (EBG) structure is proposed in this paper. The major contribution to this dual-band design is using cascaded mushroom-like units which operate at different frequencies. The position of via is moved off the center of the metal patch to get a lower resonant frequency and the effects of the radius of via are considered at the same time. The method of suspended microstrip is utilized to measure the band-gap characteristics of the EBG structures. Several dual-band EBG structures are designed and compared. Results show that this novel cascaded structure offers additional flexibility in controlling the frequencies of the stopband over a wide range. The cascaded dualband EBG structure has potential application to dual-band antenna and circuit.

The third generation promises increased bandwidth up to 384 Kbits/s for wide area coverage up to 2Mbits/s for local area coverage. A smart antenna technique has been developed specifically to meet the bandwidth needs of 3G [5, 7, 12, 14]. Smart beamforming provides increased data throughput for mobile high speed data application. Here in this paper we worked on MVDR Beamforming scheme for continuing demand for increased bandwidth & better quality of services. Adaptive minimum variance beamforming can be easily implemented to increase capacity as well as suppressing co-channel interference & to enhance the immunity to fading. The computer simulation carried out in MATLAB platform shows the signal processing technique optimally combines the components in such a way that it maximizes array gain in the desired direction simultaneously minimize it in the direction of interference [1, 3, 15, 16].

The modifiedWatson transform is applied to the Mie series expression of the electromagnetic field scattered by a high frequency plane wave incident on an infinitely long double negative cylinder. The Debye expansion is applied to the Mie series coefficients to obtain a physical insight into the scattering mechanisms and achieve an efficient approach for the computation of the scattered field. The first two terms of the Debye series are computed using the residue series in the geometrical shadow regions and using the steepest descent method in the geometrically lit regions. It is observed that the results obtained from the series and from the modified Watson transform are in good agreement. The angular boundaries for the geometrically lit and the geometrical shadow regions of the double negative cylinder corresponding to the first two terms of the Debye series are determined. These are compared with the corresponding angular boundaries for a double positive cylinder. It is observed that the spatial extent of the geometrical shadow of the double negative cylinder corresponding to the second term of the Debye series is very small compared to that of the double positive cylinder due to the negative refraction in the double negative cylinder when the magnitude of the refractive index n is greater than √2.

This paper talks about the adiabatic parameter dynamics of Gaussian and super-Gaussian optical solitons that propagate through dispersion-managed optical fibers. These parameter dynamics are useful in further study of various aspects of optical solitons, including the quasi-particle theory of optical solitons, collision induced timing jitter, the four-wave mixing and various other features. These perturbation terms and its corresponding adiabatic dynamics also can be used to study the aspects of ghost pulses and the effects of randomness in dispersion-managed optical fibers.

The imaging method when a lossy layer (e.g., a defected metallic slab or a plasma layer) is present between the target and the sensor is demonstrated using the concept of active left-handed material (LHM). The effect of the lossy layer to the reflection coefficients measured by the receiver can be cancelled by imaginatively adding an active LHM layer, which has a same thickness as the lossy layer but an opposite sign of the constitutive parameters. Therefore, the updated reflection coefficients obtained after this data process look like the lossy layer has been removed, which leads to a significant improvement of the target imaging. When the lossy layer is inhomogeneous due to the existence of small defects, we use a homogenization procedure based on the Drude model to characterize its effective constitutive parameters. Our simulation examples shows the effectiveness of the proposed method.

When airborne forward looking planar antenna is used to detect ground moving target, targets may be masked by strong clutter due to high sidelobes of the antenna pattern. In this paper, transmitting pattern is synthesized via convex optimization in order to suppress clutter from ground. Transmitting pattern has a low sidelobe illuminating short ranges and a high sidelobe focused into sky and remote ranges, which results in a relative small beamwidth in the elevation plane. In the azimuthal plane, transmitting pattern can form some notches in some fixed directions where strong clutter and interference exist. With insufficient training data due to a dispersion of clutter spectrum along range, adaptive receiving pattern with low sidelobes can be obtained by convex optimization when detecting remote targets. Simulation results show that transmitting and receiving patterns can effectively be designed via convex optimization for airborne forward looking radar.

A planar half mode substrate integrated waveguide (HMSIW) broadband bandpass filter is proposed. It is realized by cascading a lowpass filter and a highpass filter. A transmission line with half mode substrate integrated waveguide (HMSIW) on the circuit board has the characteristic of highpass, while a periodic uniform photo band structure (PBG) array has the characteristic of bandstop. Combining these two structures, a novel compact broadband bandpass filter (BPF) is fabricated and measured. Measured results show that the proposed BPF has wide bandwidth from 11.8 GHz to 23.8 GHz, all the measured insert loss are less than 2.1 dB, return loss are less than 9 dB in the passband. The BPF achieves a wide stopband with 34 dB attenuation low to 5GHz and 27 dB attenuation up to 35GHz.

A simplified expression for the eddy current loss in laminated rectangular core is obtained using linear electromagnetic field analysis. The treatment takes cognizance of current interruption phenomena, by considering capacitive effects of insulation regions. Analysis presented in this paper assumes identical field distribution in each lamination and ignores eddy currents in insulation regions.

In this paper,the propagation model considers the two half-spaces as a homogeneous isotropic medium and one-dimensionally anisotropic medium. From the exact formulas for the transient field with delta-function excitation,it is obtained readily the exact formulas for the transient field excited by a horizontal electric dipole with Gaussian excitation when both the dipole point and field point are located on the boundary between a homogeneous isotropic medium and one-dimensionally anisotropic medium. It is seen that the final exact formulas can be expressed in terms of several fundamental functions and finite integrals,which are evaluated easily.

An open resonance cell (ORC) with finite-length cylindrical mirrors is suggested for making absolute measurements of complex permittivity in the case of stretched cylindrical specimens or liquid dielectrics in cylindrical containers. For H-polarization, we report ORC features simulated in rigorous electromagnetic terms using a twodimensional (2-D) model of an open resonator with cylindrical mirrors and a dielectric test rod inserted. On this basis, the ORC laboratory prototype with finite-length mirrors was built. The measurements of dielectric test rods were performed in the 10 mm wave band. In the studies of dielectric materials, E-polarized modes of the cylindricalmirror ORC demonstrate some specific features, which are discussed, too

This paper presents a novel method for microwave breast cancer detection using a parallel-plate waveguide probe. The method is based on detecting the dielectric contrast between a malignant tumor and its surrounding tissues. Our analysis and simulations indicate that scattered signals from a tumor (modelled as a lossy dielectric sphere with higher dielectric constant than the surrounding tissues) received in the form of S parameter S₁₁ have resonating characteristics in the frequency range of 1 to 7 GHz. A frequency scan of the resonant scattered signals provides data of the presence and location of the tumor. Through numerical examples, the effectiveness of the proposed methodology to detect breast tumors of different sizes, embedded at different depths and to distinguish a tumor from clutter items is demonstrated.

The recurrence dispersion equation of coupled single-mode waveguides is modified by eliminating redundant singularities from the dispersion function. A recurrence zero-bracketing (RZB) technique is proposed in which the zeros of the dispersion function at one recurrence step bracket those of the next recurrence step. Numerical examples verify the utility of the RZB technique in computing the roots of the dispersion equation of the TE and TM modes of both uniform and non-uniform arrays.

This paper deals with Approximate Analytical Solutions to nonlinear oscillations of a conservative, non-natural, single-degreeof- freedom system with odd nonlinearity. By extending the Variational approach proposed by He, we established approximate analytical formulas for the period and periodic solution.To illustrate the applicability and accuracy of the method, two examples are presented: (i) the motion of a rigid rod rocking back and forth on the circular surface without slipping, and (ii) Cubic-Quintic Duffing Oscillators. Comparison of the result which is obtained by this method with the obtained result by the Exact solution reveals that the He's Variational approach is very effective and convenient and can be easily extended to other nonlinear systems and can therefore be found widely applicable in engineering and other sciences.

Abstract-In this paper, a novel ultra-wideband switched-beam antenna system based on 4×4 two-layer Butler matrix is presented and implemented to be used in hostile environment, such as underground mines. This matrix is based on the combination of a broadband twolayer slot-coupled directional coupler and a multilayer slot-coupled microstrip transition. With this configuration, the proposed matrix was designed without using any crossovers as used in conventional Butler matrices. Moreover, this new structure is compact and offers an ultra-wide bandwidth of 6 GHz. To examine the performance of the proposed matrix, experimental prototypes of the multilayer microstrip transition and the Butler matrix were fabricated and measured. Furthermore, a three 4-antenna arrays were also designed, fabricated and then connected to the matrix to form a beamforming antenna system at 3, 5.8 and 6 GHz. As a result, four orthogonal beams are produced in the band 3-9 GHz. This matrix is suitable for ultrawideband communication systems in confined areas.