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The method of mode matching (MM) is used to construct ideal waveports in the context of the method of moments (MoM). The waveports can provide not only excitations as sources but also perfectly matched loads for traveling-wave slotted waveguide antennas. Additionally, the application of the higher order basis functions (HOBs) in MoM significantly reduces the number of unknowns compared to the RWG basis functions. Numerical results show that the proposed method is accurate and efficient for traveling-wave slotted waveguide antennas. Finally, a Ka-band waveguide array with 1976 narrow-wall slots is solved using a high-performance cluster. [ABSTRACT FROM PUBLISHER]

In this letter, a novel compact tri-band bandpass filter (BPF) with high selectivity is presented. The proposed tri-band performance measure is realized by using eight sets of resonators, i.e., two- and three-section stepped impedance resonators (SIRs). The three-section SIR is designed for determining the three passbands and providing the electric coupling, while the two-section SIR is used for determining each passband respectively and providing the magnetic coupling. Then, coupling structures with two transmission zeros near each passband edge are presented, therefore, the band selectivity of the filter is much improved. The three passband frequencies could be independently designed and tuned. This novel tri-band BPF is fabricated and the measured results are in good agreement with the full-wave simulation results. [ABSTRACT FROM AUTHOR]

A hybrid time-domain method combing finite-difference and cell-centered finite-volume method is presented in this paper. This method is applied to solve three dimensional electromagnetic problems which involve media having finite conductivity. The fractional-step technique (FST) for FVTD scheme is applied to solve these problems. Local time-step scheme is used to enhance the efficiency of this method. Numerical results are given and compared with a reliable numerical method, which is used to show the validation of this method. [ABSTRACT FROM AUTHOR]

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°. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Currently, more and more practical engineering applications place antenna system on the electrically large platform. This paper deals with the problem of antennas mounted on large platform from two aspects--radiation pattern and system electromagnetic compatibility (EMC). To achieve an accurate and effective computation, this paper applies method of moment (MoM) with Higher-order basis functions solver with large-scale parallel computation technique. And finally some real-life examples are presented to describe how to install antennas on the platform reasonably. [ABSTRACT FROM AUTHOR]

Parallel FDTD method is applied to analyze the electromagnetic problems of the electrically large targets on super computer. It is well known that the more the number of processors the less computing time consumed. Nevertheless, with the same number of processors, computing efficiency is affected by the scheme of the MPI virtual topology. Then, the influence of different virtual topology schemes on parallel performance of parallel FDTD is studied in detail. The general rules are presented on how to obtain the highest efficiency of parallel FDTD algorithm by optimizing MPI virtual topology. To show the validity of the presented method, several numerical results are given in the later part. Various comparisons are made and some useful conclusions are summarized. [ABSTRACT FROM AUTHOR]

A novel printed monopole antenna with a pair of parasitic patches for wideband operation is proposed and studied. With the use of parasitic patches along the microstrip feed line, a good performance of bandwidth enhancement is obtained. The measured impedance bandwidth, defined by voltage standing wave ratio (VSWR) = 2, can operate from 2.3 to 6.2 GHz. A tri-band printed monopole antenna is created by introducing two notched bands in the wideband antenna. Etching an n-shaped slot on the radiating element and embedding a U-shaped parasitic strip on the bottom, two notched bands from 2.78 to 3.34 GHz and from 3.78 to 5.1 GHz are achieved. The measured impedance bandwidths of the tri-band antenna are 410 MHz (2.37-2.78 GHz), 440 MHz (3.34-3.78 GHz) and 1000 MHz (5.1-6.1 GHz), which can meet the bandwidth requirements of 2.4/5.2/5.8 GHz wireless local area network (WLAN) and 2.5/3.5/5.5 GHz worldwide interoperability for microwave access (WiMAX) standards. In addition, the proposed antennas have good omnidirectional radiation characteristics and stable gains over the whole operating bands. [ABSTRACT FROM AUTHOR]

A compact ultra-wideband (UWB) bandpass filter (BPF) with simultaneous narrow notched band and out-of-band performance improvement is presented. The UWB BPF is built up using the hybrid microstrip and coplanar waveguide (CPW) structure. By employing the split-ring resonator (SRR) which is defected on the lower plane, the narrow notched band was introduced. The center and bandwidth of the notched band can be controlled by adjusting the length and width of the SRRs. A novel cross-shape patch is constructed to implement transmission stopband in the upper out-of-band so as to suppress the spurious passband. The novel UWB BPF is designed and fabricated. The measured insertion loss is less than 1.6 dB, the return loss is more than 13 dB and the variation of group delay is less than 0.12 ns. The width of narrow notched band is about 0.15 GHz and the attenuation is 18 dB at the center frequency of 5.76 GHz. The upper stopband is up to 15.2 GHz with rejection greater than 20 dB. [ABSTRACT FROM AUTHOR]

Differential evolution (DE) is a promising evolutionary algorithm for solving optimal reactive power flow problems, but it requires relatively large population to avoid premature convergence. In order to overcome this disadvantage, a novel decomposition and coordination method based on the cooperative co-evolutionary architecture and the voltage-var sensitivity-based power system decomposition technique is proposed and incorporated with DE in this paper. It is implemented with a three-level parallel computing topology on a PC-cluster. Based on the IEEE 118-bus system test case, the effectiveness of the proposed method has been verified by comparison with the parallel basic DE not using the decomposition and coordination technique. [ABSTRACT FROM AUTHOR]