The resonant frequency of a microstrip patch (rectangular, square, and circular) changes as soon as an identical patch is brought closer than 0.2λ. Closed form expressions are presented for the E-plane coupled configuration from which this altered resonant frequency may be easily computed. These expressions may be readily used in the computer aided design of microstrip antenna arrays.

In this paper, we model an array of pyramid electromagnetic wave absorbers and calculate the return loss of this array using the FDTD method. For modeling the frequency dependent of the absorber, the Debye model is used. In doing so, a 3 × 3 structure of nine pyramid absorber is chosen instead of the array. The results are compared with capacitance and homogenization methods using average values for ε [10]. The results clearly show that the FDTD is an accurate method for calculating the return loss of an array of pyramid absorbers as compared with three other existing methods, and can be used to simulate the array of pyramid absorbers with different sizes in a wide range of frequencies.

This paper presents the result for antenna factor of microstrip patch antenna when used as electromagnetic interference (EMI) sensor. Antenna factor is an important parameter of a sensor used for EMI measurements. The microstrip antenna has found wide application as transmit and receive antenna in modern microwave systems. In this paper, a new application of microstrip antenna as EMI sensor is presented. The result for antenna factor versus frequency of a microstrip patch antenna is presented using commercial software CST Microwave Studio. Also the experimental results for a prototype antenna are presented and compared with the simulated result.

Based on the theory about charge moment tensor and the magnetic moment of a rotational charged body, and by means of Eulor's equation for a rotational rigid body in classic mechanics, the Lagrangian and the dynamic equation of a charged dielectric rigid body under a uniform magnetic field has been derived; Also two symmetric simple cases have been solved or analyzed under condition of slow rotation and no gravitation, the corresponding invariants have also been found.

In the recent years, extensive studies have been done to design space-time codes appropriate for communications over fading channels in multiple input-multiple output (MIMO)systems. Most of these designs have been based upon the assumption that the channel fading coefficients are uncorrelated hence independent jointly Gaussian random variables. Naturally the best strategy in such situations that the elements of the channel matrix are independent is to employ diversity techniques to combat the adverse effects of these fading media and thus the most famous space-time codes, i.e., orthogonal and trellis codes have been designed with an eye to realizing the maximum attainable diversity order in a MIMO system. In this paper, we will remove this almost ever-present yet practically difficult to meet condition and shall introduce a new linear space-time block code that due to having some inherent redundancy as well as diversity is wellsuited to correlated fading channels. We will discuss the properties of the proposed code, derive its maximum likelihood (ML) decoder and provide simulation results which show its superiority to the highly used orthogonal space-time block codes in a wide range of signal to noise ratios in correlated fading channels.

Diffraction of an electromagnetic plane wave from a slit in an impedance plane has been presented. The method is based on Maliuzhinets technique for impedance surfaces. Comparison of the field patterns with different values of the face impedance are also presented.

The matched filter (MF) is known as the fastest method for acquisition of DS-CDMA signals. Power consumption of the MF is a key issue for realizing multimedia hand-held terminals. We proposed a new Analog Matched Filter using Sample-and-Hold (S/H) circuit, which performs correlation between an input signal and a filtering coefficient employed for modulation in fully analog domain, eliminating the need to Analog-to-digital (A/D) conversion, so reduces power consumption and chip area. Simulation results reveal that the proposed circuit dissipates 2.3 mW power consumption at a chip rate of 16.7 MHz with 3.3 V power supply for 15 taps configuration. The proposed analog architecture could improve the performance of mobile terminals.

A new canonical scattering problem consisting of the propagation of the dominant TEM mode at the finite-length impedance discontinuity in the outer conductor of a coaxial waveguide is solved. The contributions from the successive impedance discontinuities are accounted for through the solution of a modified Wiener-Hopf equation. Some graphical results displaying the reflection and transmission characteristic are presented.

The performance of wideband radar system may be degraded by signal distortion occurring in anyplace of the transmission channel of the system. If the amplitude response is not flat or the signal delay is not constant in the transmission of the wideband signal, then signal distortion will occur, which can reduce the SNR and resolution. The available theory indicates that a small sinusoidal ripple variation in either amplitude-frequency or phase-frequency response of a linear system will cause signal distortion and the phenomena of paired echoes in the output signals of the time domain. In this paper, whether a dispersive transmission line with discontinuities will lead to the phenomena of paired echoes is discussed by means of finite difference time domain (FDTD) method and theoretical analysis. The results show that the technique of paired echoes is unsuited to analyze the influence of dispersive transmission line with discontinuities on time domain pulse signal. The method of Taylor series expansion shall be chosen as a more appropriate method. Meanwhile, simulations also show that a pulse signal transmitting in dispersive transmission lines with discontinuities including passive components such as filters and directional couplers will not lead to the phenomena of paired echoes.

Rain rate and rain attenuation predictions are one of the vital steps to be considered when analyzing a microwave satellite communication links at the Ku and Ka bands. In this paper, tools for the prediction of rain rate and rain attenuation are presented in the form of contour maps for Nigeria using a massive rainfall data bank of 30 years which are taken from measurements made from the coast to the arid region of Nigeria. Rain-rate maps for the country of Nigeria were developed using the models purposely designed for tropical zones while ITU-R models were used for the rain-attenuation maps. The information from these maps will be a good preliminary design tools for both terrestrial and earth-satellite microwave links and also provide a broad idea of rain attenuation for microwave engineers.

This paper starts with the characteristics and advantages of microwaves processing. The shortcomings of fixed frequency, typically at 2.45 GHz were also mentioned. On account of this, the newly developed variable frequency microwave (VFM) fabrication was mentioned and adopted in place of the fixed frequency process. Two cases of fixed frequency microwave processing of materials were described; the characteristics and pros of each case was mentioned and commented. Two cases of processing materials using variable frequency microwave facility (VFMF) were mentioned; the advantages and limitations of each case were discussed. The microwave processing of materials provides improved mechanical, physical and electrical properties with much reduced processing time. Furthermore, variable frequency microwave processing is more superior to its fixed frequency counterpart except that the cost of the facilities of the former is much higher than the latter at this point in time but it appears that the price will drop in the coming ten years.

Perfect electromagnetic conductor (PEMC) has been introduced as a generalization of both the perfect electric conductor (PEC) and the perfect magnetic conductor (PMC). In the present paper, the basic problem of reflection and transmission of an obliquely incident plane wave at the interface of a PEMC half space or slab is considered. It is found that the field outside the PEMC medium can be uniquely determined but the interior field requires some assumptions to be unique. In particular, definition of the PEMC-medium condition as a limit of a Tellegen-medium condition and extraction of certain virtual fields (metafields) are shown to make the field inside the PEMC medium unique.

Retrodirective arrays have garnered much attention due to the unique feature of automatically responding to an interrogator without any prior knowledge of the location of the incoming signal. This paper describes the basic concept of retrodirective array technology, discusses the three retrodirective array topologies with their advantages and disadvantages. Characterizations of the selfsteering performance in a retrodirective antenna array are described. A series of array design considerations in the retrodirective array systems is presented, and further researches in this area are presented.

Fractional curl operator has been utilized to study the fractional order surface waveguides. Fractional order surface waveguides may be regarded as intermediate step of two surface waveguides which are related through the principle of duality. Fractional eigenvalue equations are examined at the interface between dielectric medium and free space, for various values of fractional order parameter result in different fractional surface wave modes.

Antenna diversity is a well-known technique to enhance the performance of wireless communication systems. In order to create an antenna diversity system on a wireless device, two or more antenna elements could be placed in positions. However, it is difficult to implement multiple antennas on handheld terminal. A compact planar inverted-L diversity antenna for handheld terminals is provided. Three diversity antennas operating at 2.15 GHz are designed. The isolation is found to be better than 13 dB and the usable bandwidth is about 13% in measurement. The measured radiation patterns are obtained that the proposed diversity antenna attains 2 dBi gain.

To enhance the flexibility of the parallel FDTD for the analysis of the bio-electromagnetic problems, a universal and efficient interpolation technique based on the super-absorbing boundary principle is presented, which can improve the interpolation accuracy and ensure the stability of the parallel FDTD iterative procedure. Using this technique, we calculate the SAR (Specific Absorption Rate) values in the head for two different human-body postures. In the iteration procedure of parallel FDTD, the data are exchanged between adjacent subdomains with the interpolation technique. Thus, the meshes can be created in local coordinates, which makes it convenient to build the human model in the different posture and use position for FDTD computing. The results show that the change of human-body posture only brings about a slight decrease (within 6.8%) in the peak SAR values, whereas the SAR values in the brain, as a critical organ, are sensitive to the change of the body posture, and it increases by 28% at maximum for the 1-g averaged peak SAR.

The electromagnetic resonances of a spherical cavity, with a perfectly conducting wall and filled with a homogeneous isotropic chiral medium, is studied using the spherical vector wavefunctions. The characteristic equation and the expressions for the field components, when chirality reaches its maximum value, are derived. The characteristic equation is obtained by imposing the boundary condition on the wall of the spherical cavity. The characteristic equation is solved numerically and reported for the first five modes. These modes are hybrid modes. They are classes as either hybrid electric (HE) modes or hybrid magnetic (HM) modes. The explicit expressions for the field components of the HE and HM modes are given, and the field distributions of a few modes are shown. The chirality is observed to have significant effects on the resonances and the field distributions of a chiral filled spherical perfectly conducting cavity. The results show interesting properties of the cavity, which could be applied to new applications.

This paper suggests a pilot-free frequency tracking scheme for ultra-wideband orthogonal frequency-division multiplexing (UWBOFDM) receivers. The proposed scheme uses a frequency-domain spreaded data symbols which is provided in the current UWB-OFDM system. Based on this property, we develop an improved frequency synchronization receiver without the use of pilot symbols. The simulation results indicate that the proposed scheme achieves much better performance than the conventional pilot-based schemes.

In this paper, the high-order hierarchical basis functions are used for solving electromagnetic wave scattering problems. The multilevel fast multipole method (MLFMM) is applied to accelerate the matrix-vector product operation and the Schwarz method is employed to speed up the convergence rate of the Krylov subspace iterative methods. The efficiency of the proposed approach is studied on several numerical model problems and the comparison with conventional Kryloviterativ e methods is made. Numerical results demonstrate that the combination of the Schwarz method and the Krylovsubspace iterative method is very effective with MLFMM and can reduce the overall simulation time significantly.

In this paper a transfer matrix treatment for the reflectivity and transmissivity spectra of electromagnetic waves propagating in a nano sized multilayer periodic structure has been presented. Effect of varying the angle of incidence on the photonic bandgaps is shown. The design of a tunable polarizer by reflection which is more efficient in comparison to that obtained by reflection from a single dielectric slab, has been suggested.