This paper proposes a method for the quick estimation of the average voltages at terminal loads when the transmission line translate randomly and analyzes the sensitivities of the loads' voltages to the translation. Because nonuniform transmission lines can be approximated as n-cascaded uniform lines, the study of uniform lines is the basis. Based on the transmission-line equations, the equations are derived to estimate the average voltages, the voltage variations, and the sensitivity of the voltage to the random translation when transmission lines have random translation in their cross sections. With these equations, the average voltages at the loads, the probability distributions of the voltage variations, and the sensitivity of the voltage to the random translation can be obtained quickly. A two-wire line over the ground is studied by using the proposed method. The average voltages and the voltage variations' probability distributions agree well with those via the Monte Carlo (MC) method and the proposed method is more efficient. The results show that the sensitivities of the voltages at the loads to the random height increase with the terminal sources but decrease with the height.

We present Coplanar-Planar Goubau Line (PGL) transitions designed on high-resistivity Silicon to characterize a PGL using microwave probing. These transitions are optimized in the 57-64 GHz frequency band to present excellent electrical performances despite the field disturbance of the measurement setup. As the transitions are positioned on a probe station chuck, a glass substrate is added between the transition under test and the metallic chuck to minimize the disturbance. 3-D full-wave electromagnetic field simulations performed on a commercial software and on-wafer measurements show almost comparable results in term of scattering matrix parameters. Low losses are attained with a measured average transmission parameter of 2.5 dB at 60 GHz for a length of 8 mm of a back-to-back structure with the transitions at the extremities. The measured average insertion loss and return loss per transition are better than 1.36 dB and 11 dB, respectively, with a bandwidth greater than 7% at 60 GHz for a length of 1 mm (about a half of the wavelength at 60 GHz).

This paper presents a new efficient algorithm of filtering and unwrapping phase images for interferometric synthetic aperture radar (InSAR) based on nonlinear phase model. First, we analyzed the statistical and signal properties of interferometric phase, and proposed the concept of nonlinear phase model. The model of reflecting topographic contour is used to approximate the interferometric phase variation occured over the local window. And the lower amplitude bound of the principal vector is decided and the value solution method is given, which can solve effectively and adaptively the nonlinear factor of the phase. Second, we studied the application of nonlinear phase model in interferometric phase filtering. When compared with other advanced filters, the nonlinear phase compensation filter, with a higher computation efficiency and a better phase estimation accuracy in low coherence areas, has a stronger ability to reduce interferometric phase noise in rugged terrain Finally, we introduced the nonlinear phase model to phase unwrapping, which increased the reliability of integration path and the accuracy of the phase gradient, and improved effectively the performance of phase unwrapping. And the real data processing results demonstrated the validity of the proposed nonlinear phase model and of the corresponding solutions.

A compact and low-correlation multiple input multiple output antenna system covering 1710-2690 MHz band for wireless communication standards is proposed. It comprises two identical elements with coupled feeding plate and radiating strip, and each element has a volume of 24.5×15×1.2mm³. Simulated and measured results show that it has good potentials for high-band-only mobile phone. 45% bandwidth (based on S₁₁ < -6 dB), -20 dB isolation, over 70% efficiency and less than 0.15 correlation coefficient are achieved in the frequency ranging from 1710 MHz to 2690 MHz. Several key parameters are also discussed in this study to better understand the antenna principles.

In this work we examine, for the first time, the use of classification algorithms for early-stage tumor detection with an experimental time-domain microwave breast screening system. The experimental system contains a 16-element antenna array, and testing is done on breast phantoms that mimic breast tissue dielectric properties. We obtain experimental data from multiple breast phantoms with two possible tumor locations. In this work, we investigate a method for detecting the tumors within the breast but without the usual complexity inherent to image-generation methods, and confirm its feasibility on experimental data. The proposed method uses machine learning techniques, namely Support Vector Machines (SVM) and Linear Discriminant Analysis (LDA), to determine whether the current breast being scanned is tumor-free. Our results show that both SVM and LDA methods have promise as algorithms supporting early breast cancer microwave screening.

A new thin electromagnetic soft surface of strips in which ledge edges are used to reduce the strip period width and in turns a miniaturized structure is achieved. The designed surface is tested to reduce the mutual coupling between microstrip patches separated by a half wavelength. A 20% relative bandwidth of the bandgap is achieved. Study of the effect of different parameters is presented. The measurements show good agreement with the computed results.

Based on two orthogonal linear sparse arrays (LSA) which consist of the coupled-sensors (CSs), a high resolution and no ambiguity (HRNA) method is proposed to estimate the two-dimensional (2D) angles of single source. The HRNA method first constructs a new covariance matrix to achieve no ambiguity independent angles estimation by using the covariance matrix generated by each LSA, and then computes joint elevation and azimuth angles by utilizing both the estimated independent angles and triangular relationship. For large array aperture of the LSA, the HRNA method earns a high angle resolution; however, its independent angles estimation accuracy is slightly lower than the multiple signal classification (MUSIC) with a uniform linear array (ULA). In order to enhance the independent angle estimation performance, first improved HRNA (FI-HRNA) method is developed based on the HRNA and MUSIC methods. Further, in order to decrease the computational cost, second improved HRNA (SI-HRNA) method is presented based on FI-HRNA and MUSIC methods. The proposed SI-HRNA method obtains high angle resolution, high angle estimation accuracy and low computational load. In addition, the spacing between two adjacent CSs is not limited, and thus the angle resolution and estimation accuracy can be set according to practical demand. Numerical experiment and comparison with the other existing algorithms verify the effectiveness and superior performance of the method proposed in this paper.

In this paper, a computational model is established for the finite-difference time-domain analyses of induced voltage on the overhead line at oil exploiting port under lightning strike. The MTLL approximate formulation is used to simulate the lightning strike, and convolutional perfectly matched layers are used to truncate the computational domain. A two-step method is established to calculate the coupling to the overhead lines to reduce the huge computational domain of the conventional 3-D FDTD simulation. Parallel implementation is introduced for the second-step calculation to overcome the memory storage limit of a single computer. With this model, the electromagnetic field at the adjacent areas and the induced voltage on the overhead line are studied when lightning strikes an oil derrick. It is demonstrated that the electromagnetic field decreases as the distance from the oil derrick increases, but the vertical field decrease much slower than the horizontal field. It is also shown that the transversely located overhead line will introduce lower voltage than the radially located line. As the length of the overhead line increases, the induced voltage increases and the low-frequency induction is strengthened. The overhead line should be set as low as possible to reduce the induced voltage.

In this paper, two novel vector sensors using a reduced number of radiating elements are proposed to estimate the directions of arrival of incoming electromagnetic signals in the 3D space, azimuth and elevation angles. The first one uses co-located radiating elements while the other one is based on distributed antenna elements. These two sensors combine only two half-loops and one linear monopole placed on a metallic plate in view of embedded applications. Full wave electromagnetic simulations are performed to take into account the electromagnetic coupling effects between the antenna elements. The directions of arrival estimation accuracy of electromagnetic signals incoming in arbitrary directions in the full 3D space are computed from the MUSIC algorithm. For experimental validation purpose, a prototype is manufactured and the directions of arrival measurements are performed. Then a novel vector sensor design with a reduced number of antenna elements is presented. The antenna elements are spatially distributed. An analysis is carried out to determine the largest distance between the antenna elements without causing ambiguous estimations in the 3D space . The estimation accuracy of the resulting sensor is reported. Finally the performances of these two vector sensors are compared.

A compact, low profile, dual polarized, ultra wideband, frequency selective surface is proposed. It is designed by using two similar metallic array structures separated by dielectric material FR4. The simulated reflection bandwidth (with transmission < -20 dB) for TE incident wave is 8 GHz from 2.87 GHz to 10.87 GHz corresponds to 116%. The unit cell dimension and periodicity are of the order of 0.37λ at the centre frequency. The overall thickness of the proposed FSS is 1.8 mm. The proposed FSS has higher order of band-stop response and good angular stability. The measured transmission response of FSS is very close to simulated response. Design expressions for the resonance frequencies are proposed, and the calculated results are found to be in good agreement with the simulated ones. Finally, a parametric analysis of the proposed FSS is presented.

In this paper, a printed wideband Yagi-Uda antenna with a novel folded dipole driver is proposed. The folded dipole driver is comprised of a folded dipole and a microstrip feedline which functions as an internal balun to mainly determine its wide impedance bandwidth. With the optimized parameters, an operating band of 1.69 GHz~2.72 GHz can be obtained. Besides the folded dipole driver, the broadband printed Yagi-Uda antenna also consists of three directors and a reflector. Its wideband performance is mainly determined by the folded dipole driver, while the reflector and directors improve its performance slightly. By optimizing the geometrical parameters of the folded dipole driver, a bandwidth of 61.8% (1.53 GHz~2.93 GHz) for return loss being higher than 10 dB is achieved. The proposed printed Yagi-Uda antenna is realized on FR4 substrate with a measured operating bandwidth of 62% (1.51 GHz~2.94 GHz), a flat gain (5.6 dB~7.3 dB), more than 10dB front-to-back ratio and lower than -15 dB cross-polarization level.

A goal of this work is to find a possible explanation of the experimental results of [1] where the wireless power transfer between two coils is investigated. We show that this wireless power transfer is provided by the longitudinal component of the EM field. Using Jefimenko's approach of solving the Maxwell equations we show that under specific conditions the longitudinal component drops with the distance as 1/R. This result dependence can explain the experimentally detected dependence of the transferred power in the experiment.

The range profile (RP) and the inverse synthetic aperture radar (ISAR) image are the useful radar signature for classifying unknown targets because they can be used regardless of day-night and weather conditions. Since classification that uses RP and ISAR is heavily dependent on flight conditions, however, much more study is required on this topic. This paper proposes an efficient method of classifying targets by using a classifier-level fusion of RP and ISAR as well as a scenario-based construction method of the training database. Simulation results using the five targets composed of point scatterers prove that the proposed method yields high classification results when the targets are flying in a variety of directions at both short and long ranges.

In this paper, we propose a novel UHF RFID coupled slot metallic tag antenna with a radome. The proposed tag antenna consists of a frequency tuning slot, imaginary part tuning slot, real part tuning stub, micro-chip, and radome. All simulations were carried out using an Ansys HFSS simulator. The RFID tag antenna was designed and fabricated for use in the Korean and Japanese UHF band of 916.7 to 923.5 MHz. The measured 3 dB frequency bandwidth is 914 to 926 MHz. The measured read range is 12 m on a metallic surface. Details of the proposed tag antenna design, as well as simulated and measured results are presented and discussed.

Cuckoo optimization Algorithm (COA) is employed for the optimization of linear and non-uniform circular antenna arrays. COA is a novel nature inspired computing algorithm which is motivated by the life of Cuckoo. Like other nature-inspired algorithms, COA is also a population-based method and uses a population of solutions to proceed to the global solution. The method of COA is used to determine a set of parameters of antenna elements that provide the required radiation pattern. The effectiveness of COA for the design of antenna arrays is shown by means of numerical results. Comparison of results obtained with COA is made with that obtained using other popular methods. The results reveal the superior performance of COA as compared to other techniques both for design of linear and circular antenna arrays.

In this paper, the range-spread target detection in compound Gaussian clutter with reciprocal of the square root of gamma (RSRG) texture is investigated. The RSRG distribution has been proved to be a good model for texture component of extremely heterogeneous radar clutter. Taking this compound Gaussian model as a spherically invariant random process (SIRP), the Neyman-Pearson optimal detector for the range-spread target detection with known target amplitude is derived firstly. By replacing the ideal target amplitude with its maximum likelihood estimate (MLE), the generalized likelihood ratio test (GLRT) is then obtained. The statistical property of the texture component is taken into account in both of these two detectors, which makes the detectors computationally complicated. A suboptimal generalized likelihood ratio test based on order statistics (OS-GLRT) is finally proposed by substituting the texture component with its MLE. The OS-GLRT makes use of some largest observations from the range cells occupied by the most likely target scatters. The performance assessment conducted by Monte Carlo simulation validates the effectiveness of the proposed detectors.

A wideband circularly polarized patch antenna is proposed. The wide impedance and axial ratio bandwidths are achieved by the proposed feeding mechanism, which entails the use of a circular microstrip line coupling through four Γ-shaped slots to generate four sequentially phased sources to excite the single layer patch antenna. The proposed antenna can provide an SWR bandwidth of over 16.5% (for SWR<1.5) and an axial-ratio bandwidth of 13.3% (for AR<3 dB). The performance of the antenna has been confirmed by both measurement and simulation. The antenna gain is enhanced and backlobe radiation is reduced by placing a reflector at an optimized location.

An approach based on the use of the arithmetic of intervals and Interval Analysis for the solution of inverse scattering problems is presented and assessed. By exploiting the property of the Interval Analysis to find the global minimum of a functional in a n-dimensional space, the proposed approach adopts a branch and bound process to discard the regions of the solutions space not containing the global solution, while keeping those where a feasible solution is expected until a suitable converge criterion is reached. A representative set of results concerned with the reconstruction of circular dielectric objects within the first-order Born approximation are reported and discussed to show potentialities and current limitations of the proposed approach.

When the metal film is thicker than the skin depth in the working frequency band, the transmission characteristics of outer coated type are superior to the transmission properties of inner coated type under the same size. Further more, the transmission properties of the single, double, three and four groove both for inner coating and outer coating terahertz (THz) polystyrene (PS) tubes are studied in this paper. In result, the transmission properties of single and double slot are good, but the three and four slots' transmission characteristics deteriorate. In addition, slots width affects the transmission characteristics of PS tubes evidently, and the attenuation coefficient of outer coated PS tube with single slot is proportional to the slot width, so as to optimize the transmission properties of PS tube. It is a compromise for the slot width (it is better to choose appropriate slot width).

General expressions for the quality factor (Q) of antennas are minimized to obtain lower-bound formulas for the Q of electrically small, lossy or lossless, combined electric and magnetic dipole antennas confined to an arbitrarily shaped volume. The lower-bound formulas for Q are derived for the dipole antennas excited by both electric and magnetic surface currents as well as by electric surface currents alone. With either excitation, separate formulas are found for the dipole antennas containing only lossless or nondispersive-conductivity material and for the dipole antennas containing highly dispersiveconductivity material. The formulas involve the quasi-static electric and magnetic polarizabilities of the associated perfectly conducting volume of the antenna, the ratio of the powers radiated by the electric and magnetic dipoles, and the efficiency of the antenna.