Microstrip bandpass filters using a triple-mode patch-loaded cross resonator are presented in this work. First, a square patch is added at the center of a cross resonator to separate the resonant frequencies of the 1st and 2nd modes. Then, a pair of narrow slots is etched into the square patch along its symmetrical plane to split the 1st resonant mode and its degenerate mode. By changing the patch size and the slot length, the above three modes are appropriately adjusted. Two prototype filters with open-ended and stub-loaded coupled-lines are designed and fabricated to verify the design principle and to further suppress the lowest harmonic passband, respectively. Predicted results agree well with the measured ones.

The characteristics of a two-dimensional (2D) left-handed traveling-wave field-effect transistor, which is two 2D composite rightand left-handed (CRLH) transmission lines with both passive and active couplings, are discussed for generating non-attenuated waves having left-handedness in 2D. In this study, the design criteria for wave amplification are described, and the results from numerical calculations obtained by solving the transmission equations for the device are presented.

A modified Cauchy method which generates accurate duplexer and triplexer rational models from either measurements or electromagnetic analysis is presented in this paper. The modified Cauchy method has some advantages over the conventional Cauchy method because it takes into account the relationship between the transmission coefficients of each channel filter and reflection coefficient. It is suitable for duplexer and triplexer whose channel filters are connected through resonating junction. The total least square method is used to solve the system matrix. Synthesized numerical duplexer and triplexer examples verify the method successfully.

This paper presents the design and development of corner truncated rectangular microstrip antenna comprising U and inverted U-slot for multiband tunable operation, wide impedance bandwidth, and high gain. By incorporating U and inverted U-slots of optimum geometry on the radiating patch the proposed antenna operates between 3 to 12 GHz at different frequency bands and giving a peak gain of 1.73 dB without changing the nature of broadside radiation characteristics, compared to conventional rectangular microstrip antenna. The experimental and simulated results are in good agreement with each other. Design concepts of the antenna are given. The experimental results are presented and discussed. The proposed antennas may find applications in WiMax, HIPERLAN/2, and radar communication systems.

The focusing properties of six array configurations in the form of square, square with interlaced elements, square ring, cross (+) shape, cross (X) shape, and square ring plus diagonals shape arrays are investigated. The performance parameters, such as field distribution in the focal region, size of the focal spot, depth of field, level of field at focal point, and sidelobe structure, are compared. Computer simulations using MTALAB environment are performed in the investigations. The square ring and square ring plus diagonals configurations show favorable focusing properties. The resultant field patterns will help to find the arrays usefulness for hyperthermia and imaging applications.

Characteristics of reflected power from a planar interface of chiral and/or chiral nihility media have been investigated theoretically. Focus of the study is tunneling and rejection of power associated with these interfaces. Effect of polarization of incidence field and parametric dependence on reflected power have been noted. It is found from numerical results that power tunneling and rejection have strong dependency on the polarization of incidence field, angle of incidence, and chirality parameter.

Long data collecting time is one of the bottlenecks of the stepped-frequency continuous-wave ground penetrating radar (SFCW-GPR). We discuss the applicability of the Compressive Sensing (CS) method to three dimensional buried point-like targets imaging for SFCW-GPR. It is shown that the image of the sparse targets can be reconstructed by solving a constrained convex optimization problem based on l₁norm} minimization with only a small number of data from randomly selected frequencies and antenna scan positions, which will reduce the data collecting time. Target localization ability, performance in noise, the effect of frequency bandwidth, and the effect of the wave travel velocity in the soil are demonstrated by simulated data. Numerical results show that the presented CS method can reconstruct the point-like targets in the right position even with 10% additive Gaussian white noise and some wave travel velocity estimation error. p

We propose an improved method of iterative physical optics (IPO) to analyze electromagnetic scattering by open-ended cavities. The traditional IPO method uses a fixed number of iterations; if this number is too small, the accuracy of the estimated monostatic radar cross section (RCS) of open-ended cavities degrades as the incident angle of the incident field increases. The recently-introduced adaptive iterative physical optics-change rate (AIPO-CR) method uses a variable number of iterations; compared to the IPO method, it predicts monostatic RCS more accurately, but requires more computation time. In this paper, a new algorithm is devised to improve both the monostatic RCS prediction accuracy of the IPO method, and the computational efficiency of the AIPO-CR method. The proposed method, iterative physical optics-retained previous solution (IPO-RPS), calculates the currents at one incident angle, then reuses them as the initial currents of iterations for the next incident angle. In simulations of the monostatic RCS for various open-ended cavities, the IPO-RPS method was more accurate than the traditional IPO method, and computationally more efficient than both the IPO and AIPO-CR methods.

Electromagnetic Vulnerability (EMV) testing of ground vehicles and helicopters is (by necessity) performed in the immediate presence of ground surfaces (natural earth, asphalt, concrete, ship decks, and other finitely conducting grounds). The impact of the nature of these grounds on the EM coupling to the various vehicles being tested is the focus of this work. As one approach to addressing these issues quantitatively, personnel at Redstone Test Center Electromagnetic Environmental Effects (RTC/E3) Division have combined measurements on a semi-canonical physical structure along with EM modeling. In particular, a hollow 25 foot long, 4 foot diameter aluminum cylinder with a finite slot (~8 in wide) running along its entire length is positioned over (and near to) a finite conducting ground plane. Measurements of the electric fields produced both in the slot aperture and inside the hollow cylinder by an external log period dipole antenna (LPDA) positioned (broadside to the horizontal cylinder) approximately 5\,m away radiating both vertical and horizontal polarizations, respectively, are presented and discussed. The entire experimental setup (aluminum cylinder, finite aluminum ground plane, and radiating LPDA) are enclosed inside an RF anechoic chamber (inside dimensions between the respective tips of the anechoic pyramids of approximately 19 m х 9.0 m х 5.0 m). A moment method model (CARLOS) is also developed and the fields in the aperture and inside the cylinder are compared to the measured fields.

This paper presents a method for synthesizing coupled resonator diplexers composed of TX and RX filters (two types of junctions connecting the TX and RX filters are considered). For the first junction type, the common port is directly coupled to the first resonator of the TX and RX filters, respectively. For the second junction type, common node is realized by adding an extra resonator besides those of the TX and RX filters. The method is based on the evaluation of the characteristic polynomials of the diplexer using the proposed linear frequency transformation and well-established method, and then the "N + 3" coupling matrix of overall diplexer can be obtained using hybrid optimization methods. Two diplexers have been designed and fabricated to validate the proposed method.

In order to overcome the problems facing Cr-Cu-Au metallization, such as discoloration, diffusion of Cu into Au, a four-layer metallization Cr-Cu-NiP-Au is demonstrated on alumina substrate for microwave integrated circuit (MICs). A amorphous and nonmagnetic NiP barrier layer is used to avoid the diffusion of Cu into Au through the grain boundaries, which are the low activation energy path for diffusion at moderate temperature. In this view, properties of Cr-Cu-NiP-Au metallization, such as sheet resistance, solderability, bondability and adhesion strength, are evaluated. Further integrity of Cr-Cu-NiP-Au structure is evaluated by subjecting to this structure to multiple temperature cycles test. Visual observation is carried our before and after the thermal cycling test. No degradation is observed as the consequence of thermal cycling test. Test and evaluation are carried out for a multi-section broadband power divider (1 : 2) on this metallization (metal thickness 12-12.5 microns) in the 0-6 GHz frequency range. Insertion loss, return loss and isolation are comparable with Cr-Cu-Au (metal thickness 5.0-6.0 microns). Performance of the power divider and properties of this metallization system reveal its novelty over the existing.

An equivalent circuit model of coaxial probes is derived directly from the intrinsic via circuit model. As all the higher-order evanescent modes have been included analytically in the parasitic circuit elements, only the propagating mode needs to be considered by the simplest uniform-current model of a coaxial probe in numerical solvers such as finite element method (FEM) or finite difference time domain (FDTD). This avoid dense meshes or sub-gridding techniques and greatly reduces the computational efforts for accurate calculation of the probe input impedance. The derived equivalent circuit model and the new feeding technique have been validated by both analytical formulas and numerical simulations.

The direct position determination (DPD) method can improve the location accuracy compared with the traditional two-step location methods due to omitting the intermediate procedure of estimating the measurement parameters. However, the DPD methods presented so far are significantly more complex than the two-step approach. To overcome the shortcomings of the published DPD algorithms, a novel multi-target direct localization approach is firstly proposed by exploiting the jointly sparse property in the discrete spatial domain. The main idea of this paper is that the location estimation can be obtained by finding the sparsest solution according to the predefined overcomplete basis. Furthermore, the locations of targets can be obtained from noisy signals, even if the number of targets is not known a priori. Experimental results demonstrate that the proposed algorithm has superior positioning accuracy to other DPD methods and improves computational efficiency greatly.

An ultra-wideband (UWB) power divider is designed in this paper. The UWB performance of this power divider is obtained by using a tapered microstrip line that consists of exponential and elliptic sections. The coarse grained parallel micro-genetic algorithm (PMGA) and CST Microwave Studio are combined to achieve an automated parallel design process. The method is applied to optimize the UWB power divider. The optimized power divider is fabricated and measured. The measured results show relatively low insertion loss, good return loss, and high isolation between the output ports across the whole UWB (3.1-10.6 GHz).

A new wide-band microstrip phase inverter is reported in this paper. Interdigital striplines, defected ground and via holes are used to obtain 180° phase shift. The structure is simple and can be realized with ordinary microwave integrated circuit (MIC) fabrication process. The bandwidth is enhanced largely. A lumped-element model of the phase shifter is devised. The fabricated phase inverter has a bandwidth of 105.6% (2.065-6.682 GHz), with 1 dB insertion loss and a phase deviation less than 10°.

In a large number of applications, including communications from satellites, an optimal exploitation of the available power is of the outmost importance. As a consequence, isophoric array architectures, i.e., arrays using the same power in all the different entry points and achieving the amplifiers' maximum efficiency, are of great interest. At the same time, the easy reconfigurability of the power patterns results fundamental in order to get a full exploitation of the payload. In this paper, an innovative and deterministic approach is proposed for the optimal synthesis of linear phase-only reconfigurable isophoric sparse arrays able to commute their pattern amongst an arbitrary number of radiation modalities. The introduced perspective leads to an effective solution procedure for the fast design of antennas with high performance, and does not recur to computationally expensive global-optimization techniques. Numerical results concerning applications of actual interest and employing realistic element patterns are provided in support of the given theory.

This paper presents two design-and-analysis cases of a line-start axial-flux permanent-magnet motor: with solid rotor and with composite rotor. For a novel structure of the motor, two concentric unilevel spaced raised rings are added to the inner and outer radii of its rotors to enable auto-start capability. The composite rotor was coated by a thin (0.05 mm) layer of copper. The basic equations for the solid rotor ring were extracted. The motor's lack of symmetry necessitated 3D time-stepping finite element analysis, conducted via Vector Field Opera 14.0, which evaluated the design parameters and predicted the motor's transient performance. Results of the FEA show the composite rotor significantly improving both starting torque and synchronization capability over solid rotor.

In this paper, a design of new tri-band bandpass filter for the application of GSM (1.8 GHz), WiMAX (2.7 GHz) and UWB (3.3-4.8 GHz) is proposed. The first two narrow passbands are created, and the bandwidth of the third passband can be tuned by properly selecting the impedance ratio (R) and physical length ratio (u) of the asymmetric stepped-impedance resonator. To improve passband performance and form the UWB passband, a U-shape defected ground structure and extra extended coupling lines are integrated with the asymmetric SIR. Due to the three transmission zeros appearing near the passband edges, the band selectivity of the proposed filter is much improved. The filter was fabricated, and the measured results have a good agreement with the full-wave simulated ones.

This paper presents a complementary metal-oxide-semiconductor (CMOS) differential voltage-controlled oscillator (VCO) implemented with the push-push principle. The push-push VCO uses two frequency doublers stacked in series with an LC quadrature voltage-controlled oscillator (QVCO) to share the dc current with the QVCO for low power consumption. The proposed CMOS VCO has been implemented with the TSMC 0.18 μm CMOS technology, and the die area is 0.822×1.564 mm². At the supply voltage of 0.9 V, the total power consumption is 3.15 mW. The free-running frequency of VCO is tunable from 10 GHz to 11.15 GHz as the tuning voltage is varied from 0.0 V to 1.2 V. The measured phase noise at 1 MHz frequency offset is -114.93 dBc/Hz at the oscillation frequency of 9.99 GHz, and the figure of merit (FOM) of the proposed VCO is -190.0 dBc/Hz.

In order to achieve low cost and compact design, it becomes more and more popular to integrate the circuit of the on-board charger into other power electronic circuits existing in EVs. In this paper an integrated air conditioner on-board charger system based on switched reluctance motor (SRM) was proposed, and the electromagnetic behavior occurring in the SRM when working in the charging mode was investigated. Three charging patterns, viz. single-phase charging, double-phase charging and triple-phase charging were analyzed. The specific rotor positions for which the rotor can be kept still when injecting charging currents to the armature windings were identified. The optimal design for maximizing the keeping-still capability was conducted. The power losses occurring in the SRM when working in charging mode were estimated.