In this paper, the hybrid physical optics/boundary integral-finite element-mode matching (PO/BI-FE-MM) method is proposed for the analysis of the horn antenna enclosed by the electrically large radome. The radome is modeled by the PO method, and the BI-FE-MM method is implemented to the horn region. The equivalent PO currents on the radome surface are coupled into the BI-FE-MM equation of the horn region to account for the effects of the radome on the horn. With this hybrid method, the mutual interactions between the radome and the horn are fully considered. The radiation patterns, field distributions, and the S-parameters of the horns enclosed by different kinds of radome are presented.

In this paper, an improved residual carrier frequency offset estimation scheme is proposed for ultra-wideband multiband orthogonal frequency division multiplexing (UWB-OFDM) systems. The basic idea of our approach is based on the fact that two adjacent OFDM symbols convey identical information in an UWB-OFDM system. The mean square error of the synchronization scheme is derived, and its simple expression is also calculated. Finally, simulation results are demonstrated to verify the theoretical analysis in this paper.

The reflection and transmission coefficients of multilayer structures are computed by the Transmission Line Transfer Matrix Method (TLTMM) and it is shown that metamaterials (MTMs) act as frequency selective surfaces (FSSs). Several examples of multilayer structures are analyzed, which are composed of combination of common materials and MTMs with dispersion relations. Interesting and uncommon behaviors are observed for MTMs. Novel applications are treated by TLTMM and a matrix method.

This paper suggests a new method for designing of planar eight port waveguide mono-pulse comparator. Planar eight port waveguide mono-pulse comparator acts as a four-way in-phase power divider in a transmitting mode and as a mono-pulse sum and difference combining hybrid in the receiving mode. The short-slot directional coupler is converted to an equivalent magic tee by adding dielectric-slab-filled waveguide phase shifter. Four such hybrids are connected appropriately using H-plane bends to form a compact planar eight port waveguide mono-pulse comparator. Simulation results with Ansoft HFSS software are presented, which verify good performance.

In this paper, a new route for the realization of left-handed metamaterials (LHMs) is suggested. It is based on commercially available dielectric resonators with low loss and high temperature stability. By etching simple metallic strips on surface of dielectric resonators, the desired resonance modes can be enhanced while the undesired suppressed. In this way, resonance frequency of desired resonance modes can be tuned to the frequency range of interest. As a typical example, a wide-angle polarization-independent planar LHM based on disk-like dielectric resonators is proposed. Negative permeability and permittivity are realized by etching metallic strips along the electric field orientations of TE01_δ and HEM11_δ modes, respectively.

A study is made of the excitation of electromagnetic waves by spatially bounded, arbitrary sources in the presence of a cylindrical guiding structure immersed in an infinitely extended, homogeneous gyrotropic medium whose permittivity and permeability are both describable by tensors with nonzero off-diagonal elements. The axis of symmetry of the considered cylindrical structure is assumed to coincide with the gyrotropic axis. The total field is sought in terms of vector modal solutions of the source-free Maxwell equations. We determine the content of the modal spectrum and obtain an eigenfunction expansion of the source-excited field in terms of discreteand continuous-spectrum modes. The expansion coefficients of the modes are derived in explicit form. An expression for the total power radiated from sources is deduced and analyzed. It is shown that the developed approach makes it possible to readily represent the sourceexcited field without preliminary calculation of the dyadic Green's functions, which significantly facilitates the field evaluation.

A novel compact four element multiple input multiple output (MIMO) antenna is proposed. The antenna is composed of four E-shaped patch elements and operates at 5.8 GHz. The E-shaped patch antenna, operate at this frequency is designed using the Invasive Weed optimization algorithm. This algorithm is then applied to design the two and the four element MIMO antenna for high degree of isolation. In order to measure the array performance under MIMO signaling conditions a multi-port metric is used to characterize the compact array rather than the scattering matrix characterization. The designed antennas have low profile, easy fabrication, low cost and good isolation. The simulation and measurement result of reflection coefficient, mutual coupling and radiation pattern is presented.

Electrical capacitance tomography (ECT) is a relatively mature non-invasive imaging technique that attempts to map dielectric permittivity of materials. ECT has become a promising monitoring technique in industrial process tomography especially in fast flow visualization. One of the most challenging tasks in further development of ECT for real applications are the computational aspects of the ECT imaging. Recently 3D ECT has gained interest because of its potential to generate volumetric images. Computational time of image reconstruction in 3D ECT makes it more difficult for real time applications. In this paper we present a robust and computationally efficient 4D image reconstruction algorithm applied to real ECT data. The method takes advantage of temporal correlation between 3D ECT frames to reconstruct movies 4D of dielectric maps, which enhance the noise performance of and its computational efficiency, improves the speed of ECT image reconstruction. The 4D image reconstruction results are presented for experimental data from fast moving object.

Adaptive beamforming, which uses a weight vector to maximize the signal-to-interference-plus-noise ratio (SINR), is often sensitive to estimation error and uncertainty in the parameters, such as direction of arrival (DOA), steering vector and covariance matrix. Robust beamforming attempts to mitigate this sensitivity and diagonal loading in sample covariance matrix can improve the robustness. In this paper, beamformer based on particle filter (PF) is proposed to improve the robustness by optimizing the diagonal loading factor in sample covariance matrix. In the proposed approach, the level of diagonal loading is regarded as a group of particles and optimized using PF. In order to compute the post probability of particles beyond the knowledge of noise, a simplified cost function is derived first. Then, a statistical approach is developed to decide the level of diagonal loading. Finally, simulations with several frequently encountered types of estimation error are conducted. Results show better performance of the proposed beamformer as compared with other typical beamformers using diagonal loading. In particular, the prominent advantage of the proposed approach is that it can perform well even noise and error in the steering vector are unknown.

A fabricated multilayer low-temperature co-fired ceramic (LTCC) delay line (approximate 16λ_g at 9.5 GHz), using 3D meander strip line, is proposed in this paper for the first time. The advanced quasi coaxial ground vias (QCOX-GND vias) are proposed for signal vertical interconnections in this multilayer structure. These technologies obtain good performances in the whole band (9~10 GHz). Measurement results show that, besides low insertion loss and low VSWRs, low time dispersion can be achieved as ≤±0.002 ns, which is very important to a delay line. The more compact size, as 8 mm × 10 mm × 2.37 mm, can also be obtained than other delay line structures.

A dual-band printed dipole antenna with integrated balun feed is given in this paper. First, the fork-shaped slot is etched on the arms of the printed dipole antenna to achieve the dual-band operation with resonances at WLAN bands. The radiating element without balun is optimized and operates at 2.4 GHz (2180-2750 MHz) and 5.2 GHz (5040 MHz-5480 MHz) where return loss is less than -10 dB. In order to further get a lager bandwidth, a modified Marchand balun is introduced for dual-band operation, which can provide two resonances in each band to enhance impedance bandwidth. By co-designing the radiating element with the dual-band balun, an antenna covering 2150-2750 MHz and 5050-6230 MHz has been achieved. The design equations for modified balun have been presented and agreement between calculations and measurements is good.

This paper describes a memory-reduced (MR) compact two-dimensional (2-D) order-marching time-domain (OMTD) method for full-wave analyses. To reduce memory requirements in the OMTD method, the divergence theorem is introduced to obtain a memory-efficient matrix equation. A lossy microstrip line is presented to validate the accuracy and efficiency of our algorithm.

This paper describes a novel dual-band patch antenna on organic magnetic substrate for wireless local area networks (WLAN) wireless communication (at 2.4 and 5 GHz). The dual-band operation is obtained by embedding a pair of L-shaped slots. The magnetic material is adopted because the substrate can reduce the size of antenna 40%, comparing with rectangular microstrip antennas on normal dielectric substrate, and have wider bandwidths for both bands. Details of the proposed antenna design are presented and discussed, which can be a candidate for the requirement of WLAN, operating in 2.4 and 5 GHz.

The purpose of this paper is to present a complete design and analysis of a new integrated balanced transmitter operated at 4 GHz using microstrip technology. It comprises a 4-GHz two-port negative resistance oscillator and a microstrip-patch antenna resonated at 4 GHz. Three different modules are designed and analyzed. The first one used a Lange coupler as a power splitter while the second and third used a one (two)-section branch couplers. The components of the three modules are designed using full-scale computer simulation program named with MSDES; performed by the author; which takes fully into account all the discontinuities included in the microstrip lines, while the modules are analyzed and optimized using APLAC V7.61 software. The design methodologies of the two-port negative resistance oscillator and microstrip patch antenna are introduced and explained. The analyses of the designed modules show a better efficiency and good performance. The modules give a transmit-antenna gain of 15.7 dB with antenna beam widths 91.7^o and 18.2^o in E-and H-planes, respectively. The complete schematic diagrams of the transmitter modules are drawn. These modules can be used in satellite communication, Doppler and other radars, active and semi-active seekers, radio altimeters, missile technology, weapon fuzing, manpack equipment, remote sensing, feed elements in complex antennas, satellite navigation receivers, and biomedical radiators.

The PMCT probe, saying, one kind of open-ended coaxial probe adopted widely in microwave coagulation therapy of cancer, has been used to measure the complex permittivity of freshly excised specimens of normal animal tissues. The RFM model for PMCT probe is developed to extract the anticipant permittivity of specimens under test. In addition, the effects of several factors on the measurement results have been considered and discussed, including different temperature and reference materials, as well as the sampling frequency range and intervals of the rational function model. All the experiments have been conducted at the microwave frequency range from 450 MHz to 14.5 GHz.

A generalized GPS (GGPS) algorithm is proposed for the problem of reducing the bandwidth and profile of the stiffness matrix in finite element problems. The algorithm has two key-points. Firstly and most importantly, more pseudo-peripheral nodes are found, used as the origins for generating more level structures, rather than only two level structures in the GPS (Gibbs-Poole-Stockmeyer) algorithm. A new level structure is constructed with all the level structures rooted at the pseudo-peripheral nodes, leading to a smaller level width than the level width of any level structure's in general. Secondly, renumbering by degree is changed to be sum of the adjacent nodes codes to make a better renumbering in each level. Simulation results show that the GGPS algorithm can reduce the bandwidth by about 37.63% and 8.91% and the profiles by 0.17% and 2.29% in average for solid models and plane models, respectively, compared with the outcomes of GPS algorithm. The execution time is close to the GPS algorithm. Empirical results show that the GGPS is superior to the GPS in reducing bandwidth and profile.

This paper presents a novel method to enhance the pattern characteristics of the TEM horn antenna for 2-14 GHz frequency band. The conventional TEM horn antenna introduces some fluctuations in the main lobe radiation pattern over the higher frequencies, i.e., 10-14 GHz. This motivated us to propose a new method to remove the aforementioned impact by carving an arc shape to the open end of exponentially tapered plates. The associated curvature of this arc is optimized to completely remove the aforementioned fluctuation. The measurement results show that the improved TEM horn antenna structure exhibits low VSWR as well as good radiation pattern over 2-14 GHz frequency band.

This paper studies the loss effect of the line and the validity of a SPICE model for lossless transmission lines excited by an incident plane wave by using a simple structure --- a single line over an infinite perfectly conducting ground excited by an incident electromagnetic field. The frequency domain current responses calculated by the Baum-Liu-Tesche (BLT) equation with the loss ignored are compared with those through the BLT equation with loss considered to study the loss effect of transmission lines. The loss effect study shows that the SPICE model for lossless transmission line can be used for electromagnetic pulse interaction with electronic systems when the frequency is not very high or the systems are not very large. But for a sine wave of which the frequency equals the pole frequency of the line, the SPICE model may lead to significant error.

We review the research progress in reversed Cherenkov radiation in double- negative metamaterials (DNMs) starting from the first experimental verification of the DNMs reported in 2001, including theories, numerical computation and simulation and experiments. We also discuss the potential applications to particle detectors and highpower microwave or millimeter-wave devices, including the oscillators and amplifiers, and the formidable challenges needed to be resolved before the benefits of using such artificial materials can be harvested.

A heuristic particle swarm optimization (PSO) based algorithm is presented in this work and the novel hybrid approach is applied to linear array synthesis considering complex weights and directive element patterns so as to analyze its usefulness and limitations. Basically, classical PSO schemes are modified by introducing a tournament selection strategy and the downhill simplex local search method, so that the hybrid algorithms proposed combine the strengths of the PSO to initially explore the search space, the pressure exerted by the genetic selection operator to manage and speed up the search, and finally, the ability of the local optimization technique to quickly descend to the optimum solution. Four classical real-valued PSO schemes are taken as reference and synthesis results for a 60-element linear array comparing those classical schemes and the hybridized ones are reported and discussed in order to show the improvements achieved by the hybrid approaches.