In this paper, an analysis method for optical wave propagation based on photon model is presented for the characterization of optical wireless communication environment. In contrast to radio waves, optical waves have very short wavelengths, so that material properties become important and often cause diffuse reflections. Channel models including diffuse reflections and absorption effects due to material surface textures make conventional electromagnetic wave analysis methods based on ray tracing consume enormous time. To overcome these problems, an analysis method using photon model is presented that approximates light intensity by density of photons. The photon model also ensures that simulation time is within a predictable limit and the accuracy is proportional to the number of total photons used in the simulation.

This paper presents analysis and design of a compact ultra wide band (UWB) filter using three parallel folded coupled lines in a defected ground structure in multi-layer structure. Defected ground has been incorporated under the coupled lines of the filter to improve the coupling over a wide bandwidth. The closed form expressions for even and odd mode impedances for the coupled lines with defected ground have been obtained to design a filter of desired bandwidth with the proposed structure. Based on circuit models, an UWB filter for 3.1-10.6 GHz has been analyzed and the results have been compared using full wave simulations. Analytical results are satisfactorily matching with simulations. Filter exhibits a constant group delay of ±0.08 ns in the pass band. Size of the filter is 6.2 mm×3.4 mm×2.8 mm.

In this paper a new simple VHF-LB vest antenna is proposed, simulated, fabricated and tested. The simulation results for various user's positions such as standing, kneeling and prone on the ground are obtained and compared with conventional whip antenna mounted on mobile unit. It is shown that the proposed antenna outperforms the whip antenna in terms of gain and body energy absorption. The measurements results of proposed vest antenna confirm the simulation results.

Based on the equivalence principle and the reciprocity theorem, the multiple scattering up to $N$th-order by adjacent multi-particles is considered in this study. It is well known that the first-order solution can easily be obtained by calculating the scattered field from isolated targets when illuminated by a plane wave/Gaussian beam. However, due to the difficulty in formulating the couple scattered field, it is very difficult to find an analytical solution for the higher-order of the scattered field with considering the multiple scattering even for multi-canonical geometries, such as spheres, spheroids, and cubes. In order to overcome this problem, in this present work, the higher-order solutions of electromagnetic scattering for multi-particles are derived by employing the technique based on the reciprocity theorem and the equivalence principle. In specific, using the formulas of the composite scattering field obtained in this work, the bi-static scattering of plane wave/Gaussian beam by adjacent multi-spheres is calculated and the results are compared with those obtained from the numerical computations by the Time Domain Integral Equation Method (TDIEM).

PCSS low jitter trigger can reach 65 ps in the condition of high bias electric under the non-liner mode [1-5]; high power transient pulse can be gained by virtue of it. The high power transient pulse in-phase characteristic and other tenets are verified by testing axial electric field strength and axial energy density, which is energy per area at the antenna main radiation direction. In the experiment, axial electric field strength and energy density of antenna array measured in different conditions indicate that axial electric field strength is proportional to the number of antenna elements and the energy density is proportional to the square of the number of radiation units, which means the transient electromagnetic pulses could synthesize in phase perfectly.

A quasi-lumped design of a suspended stripline (SSL) bandpass filter (BPF) exhibiting high signal selectivity is proposed. In the circuit, transmission zeros were implanted to enhance the stopband signal rejection. A sample BPF having an operation band of 6.77--7.33\,GHz was fabricated and measured for performance verification of the proposed design.

Frequency selective surfaces (FSSs) with fractal four legged aperture elements are studied. Three different order fractal elements are discussed for comparison. The results show that by using this novel kind of elements, multiband FSSs with miniaturized elements can be achieved. The ratio of the first resonant wavelength to the periodicity can be up to 10.36. Four passbands for normal incidence or two stable passbands for different incident angle and polarizations can be obtained. The FSS is analyzed by the spectral domain approach.

This research consists on a ground plane modification using slots of a PIFA (Planar Inverted F Antenna) handset antenna with the objective to facilitate the integration of the feeding transmission line which connects the antenna with the RF-module. Through this technique it is possible to obtain a multiband antenna while keeping the same antenna geometry, small volume and simplifying the PCB (Printed Circuit Board) design. Numerical simulation using MoM is used to understand the effect of the slots on the groundplane. Several prototypes have been built to validate the present technique.

The echo signal characteristic of a chirp pulse train from a moving target is analyzed. It is pointed out that the range migration is caused by the migration exponential item (MEI) and can be compensated by removing the MEI. On this basis, we proposed a new practical compensation method with little computation burden through shifting control on the matching weight coefficients. The parasitical sidelobes due to the quantization effect can be restrained effectively by storing multi-groups of weight. Simulation results proved the availability of the method.

In this paper a simple strategy to detect changes in through-the-wall imaging scenarios is presented. In particular, tomographic reconstructions taken at different instants of time are exploited. This allows to increase the detectability of scatterers whose positions are varied in two different data collections. The feasibility of the technique is demonstrated with both synthetic and experimental data.

Theoretical results on the plane electromagnetic wave diffraction from a structure as a strip periodic grating on a paramagnetic layer, the permeability of which possesses negative real part in the microwave band, are obtained using analytical regularization based on the solution to the Riemann-Hilbert problem. The effect of the resonant transmission accompanied by extremely high absorption is thoroughly studied across the frequency band of the surface waves of the paramagnetic layer placed in the biasing magnetic field. This effect is caused by the surface waves of the layer excited resonantly by the plane incident wave with the diffraction grating present. The resonant frequency is electronically tuned by the biasing magnetic field.

We describe a broadband microwave test system that can measure dielectric properties of microwave low-loss materials at high temperatures using circular cavity method. The dielectric constants and loss tangents of samples at different temperatures were calculated from measured shifts of resonant frequencies and unloaded quality factors of the multimode cavity with and without sample. Detailed design and fabrication of the circular cavity capable of working at temperatures up to 1500^οC are discussed. The measurement theory and new calculation method of the radius and length of the cavity at different temperatures are presented. The hardware system was built to measure dielectric properties at wide frequency band from 7 to 18 GHz and over a temperature range from room temperature to 1500^οC. Measurement results of the dielectric properties of quartz samples are given and show a good agreement with the reference values.

Electromagnetic scattering of a line source from a perfect electromagnetic conductor (PEMC) circular cylinder coated with double positive (DPS) material or double negative (DNG) material is investigated theoretically. The response of the coated PEMC circular cylinder is observed and it is noted that how the results obtained for this configuration differ from those of a coated perfect electric conductor (PEC) circular cylinder. It is assumed that both the PEMC cylinder and the coating layer are infinite along the cylinder axis. The comparison of directivity of coated PEMC cylinder and coated PEC cylinder is presented.

In this paper, a new numerical technique, passing center swing back grids (PCSBG's) for the resolution of the grid distortion difficulty due to the rotational motion of objects is introduced. This proposed swing-back-grids approach alongside of the method of characteristics (MOC) is developed to solve EM scattering problems featured with rotating objects. The feasibility of such combination is apparent from the fact that MOC defines all field quantities in the centroid of the grid cell. The scattered EM fields from a rotating circular cylinder under the excitation of an EM pulse are predicted in two dimensions and the electric field distributions recorded at several time instances are demonstrated. In order to confirm that the cylinder is rotating and scattering EM fields simultaneously, the circular cylinder is uniformly divided into an even number of slices with one perfect reflector and one non-reflector alternatively since a rotating circular cylinder causes no relativistic effects.

In this paper, we proposed an efficient knowledge-based Support Vector Regression Machine (SVRM) method and applied it to the synthesis of the transmission lines for the microwave integrated circuits, with the highest possible accuracy using the fewest accurate data. The technique has integrated advanced concepts of SVM and knowledge-based modeling into a powerful and systematic framework. Thus, synthesis model as fast as the coarse models and at the same time as accurate as the fine models is obtained for the RF/Microwave planar transmission lines. The proposed knowledge-based support vector method is demonstrated by a typical worked example of microstrip line. Success of the method and performance of the resulted synthesis model is presented and compared with ANN results.

Bandstop filter (BSF) is first constructed using open stubs and spurline. The stop bandwidth of this conventional structure is further increased by placing a complementary split ring resonator (CSRR) exactly below the 50 Ω microstrip line. By embedding this BSF with a wide rejection band in the input port of the PCML bandpass filter, unwanted passbands of bandpass filter is eliminated. To demonstrate this, we have designed, fabricated and tested a first order Chebyshev bandpass filter centered at 0.9 GHz with 10% fractional bandwidth (FBW). This bandpass filter is cascaded with the newly proposed BSF. Simulation and measured results shows a harmonic rejection upto 5f₀ with more than 20 dB rejection level.

A complex dielectric constant for poplar and monstera delicious's obtained by Ulaby at 10 GHz has been revised at 4 mm band. A measurement setup operating at 4 mm was established for making comparison between modeled and measured values. Results basically show that their electromagnetic transparency increases by drying as expected. While moisture content increases from 0% to 60%, transmitted power decreases from 95% down to 22%; reflection goes up to 50% and the absorption reaches from 1% to 20% for monstera leaf. A model developed for poplar responds much better than the model revised for monstera leaves.

The synthetic aperture radar (SAR) signatures of moving target are the basis of ground moving target detection and imaging (GMTI&Im). However, previous studies are mainly based on the 2-D separable SAR processing, and little work has been done to investigate the signatures of moving target after the application of a particular fine resolution SAR image formation algorithm. In this paper, the spectrum of moving target after polar format algorithm (PFA) processing is derived. Based on this spectrum, detailed analysis on the SAR signatures of moving target, including the geometric displacement, residual range migration, and the defocusing effect in both range and azimuth dimensions are performed. Simulation results validate the theoretical analysis.

The time-to-frequency-domain conversion is often required in many applications of the finite-difference time-domain (FDTD) method. This paper presents a new FDTD time-to-frequencydomain conversion algorithm based on the optimization of nonuniform fast Fourier transform (NUFFT) with several redundancy-reduction techniques. The proposed algorithm can perform the FDTD conversion at multiple desired frequencies without the limitation of uniformly spaced frequencies in the fast Fourier transform (FFT). In addition, with a very low storage cost, the algorithm can be much more efficient than other FDTD conversion techniques if a moderate number of frequencies or more are of interest. This algorithm is very useful for some FDTD applications.

The constitutive parameters measurement of thin solid and liquid materials by transmission-reflection methods generally suffers from a) the requirement of the transformation of measured scattering parameters from the reference plane to the end surfaces of the material (measurement plane) and b) inaccurate knowledge on the length of the material, if the material does not fill the entire measurement cell (a waveguide or coaxial-line section). In this research paper, a microwave waveguide method for constitutive parameters determination of these materials is proposed to simultaneously eliminate these problems. There are three main advantages of the proposed method as: a) it explicitly determines the constitutive parameters from measured S-parameters; b) it does not require the knowledge about sample length since it directly measures it as a byproduct of the method; and c) it offers a self-checking feature to trace the performance and accurateness of measurements. This feature does not depend on the constitutive parameters of the sample. We measured the complex permittivity of some thin solid and liquid test samples for validation of the method.