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The Archimedean spiral antennas are widely used as a kind of broad-bandwidth antennas. This paper presents an Archimedean spiral antenna and its directivity performance. A metal cavity is used to reflect unwanted power in order to get unidirectional pattern. To overcome the bandwidth limitation of the hollow metal cavity, the cavity with three metal plates are proposed, and the simulation results...
In this study, we present an interfacial operator approach for solving guided wave modes of plasmonic crystals. They are formulated as an eigenvalue problem of the wavenumber along the axis of the crystal. In this formulation, the permittivity and permeability of the metallic component can be arbitrary functions of frequency. Moreover, a coupling interface method is introduced to facilitate accurate...
Electromagnetic monitoring methods are in good graces of the experts on short-term and immediate earthquake prediction. Radio sounding technology is one of the methods which has been studied for more than 10 years in Russia and Japan. The research has showed the functions in revealing the seism-ionospheric coupling mechanism and earthquake prediction. Various ways of radio sounding technology to monitor...
This paper gives a new image feature extraction technique coined two-dimensional clustering-based discriminant analysis (2DCDA), which is based on 2D image matrices for constructing the scatter matrices and assumes that the data obeys the multimodal distribution. The detailed procedure of 2DCDA is to first partition each class of the data into multiple clusters via fast 2D global k-means clustering...
A numerical method is presented in this paper to determine the transient electric field inside wind turbine towers struck by lightning. The tower is modelled by a coupled RLC network and the lightning transient responses of the network are calculated by solving its equivalent calculation circuit. The formula of transient electric field is derived from Maxwellpsilas equations based on the obtained...
New micromachining techniques now provide the technology to fabricate vacuum electron devices with dimensions suitable for operation in terahertz region. In this paper, results of theoretical and numerical simulation studies of a MW-class, large diameter terahertz wave generator based on the Cerenkov principle are presented. The device consists of a miniaturized foilless diode as well as an oversized...
A simple imaging system operating at 0.5 THz band, utilizing nearly quantum-limited sensitive NbN superconductor-insulator-superconductor (SIS) mixers, is demonstrated. The system is proved to have a spatial resolution of 2.7 mm and sensitivity of 1.6 K with a 100 mm diameter collecting Teflon lens. The results show that this imaging modality is applicable to diverse areas in active or passive mode.
A novel microwave sensor based on rectangular waveguide filled with a double negative (DNG) material is modelled using a full wave electromagnetic commercial simulator CST. Simulating results show that evanescent mode are amplified and transmitted through the structured DNG materials within the frequency band that exhibits negative permittivity and permeability. Evanescent mode is sensitive to permittivity...
This novel antenna presented consists of top substrate with a quasi-square patch, middle air gap and bottom substrate with rectangular-helix-slotted ground and open-circuit microstrip feed line(50 Omega). It covers 7.9 GHZ-9.85 GHZ(VSWRles2, 20.3%). Gain ges3 dB when the ground is large enough. -3 dB beam-width is no less than 25deg both in E-plane and H-plane. The antenna also has simplicity, compactness,...
The aim of this study was to classify using a neural network LAE into mildly, moderately, and severely abnormal from a subjectpsilas P-wave. Cardiological features, wavelet features, and a combination of both were used to train the neural networks. It was found features derived from the wavelet energy spectrum performed better than the cardiological features on the test cases.
With the increase in modern communication based on wireless technology, protection against electromagnetic environment effects (E3) on systems is becoming more important. This includes reducing the electromagnetic interference (EMI) and ensuring compatibility for communication systems within, and especially protecting data links and terminals against lightning and high-power electromagnetic pulse...
Electromagnetic gear is used to transfer power through magnetic field which comes from the electrical coils installed on bearing. The input current may be used to drive the change of the output loads by adjusting on time. This paper has set up the dynamic model of the electromagnetic gear and deduced the transfer function which the electric current is input and the torque is output. According to the...
This paper analyzes the characteristics of the satellite communication system as well as the satellite communication channel and introduces the basic principles and outstanding advantages of convolutional code and MSK modulation. The combined implementation of properly chosen convolutional code and MSK modulation is a feasible scheme for the satellite communication with existing power limitation and...
This paper presents the results of study on the gain of plasma antenna. The plasma antenna is an annular fluorescent lamp driven either by 220 V AC source or by a RF signal source. A metallic antenna with same dimension is used as a reference. The far field strengths and VSWRs of these three antennas are measured. The gains of the plasma antennas relative to that of the reference metallic antenna...
Minimum redundancy linear arrays (MRLA) are widely used in radio astronomy, microwave radiometry, radar and other fields. Based on the Fourier properties of arrays with optimal co-array properties, the co-array properties of MRLAs with minimum sidelobe level are presented for the first time, validated by simulations of different MRLAs with 5~9 elements. The upper bound of the peak sidelobe level (PSL)...
Presents a new architecture of the reflectarray antenna, it is useful to reduce the weight and the volume of antenna when it is undeployed. A detailed method of computing the cable system was introduced. Found that the axial force on the aluminum laminate boom is relatively small when the spans of the reflector boundary is odd. The most fundamental structural component of this antenna is the spring...
In this paper a wideband omnidirectional printed dipole array antenna with high gain is proposed by cascading the double side printed twin dipoles. The measured relative bandwidth for VSWR<1.5 or S11<-14 dB reaches 10% (3893 MHz~4314 MHz), and the measured gain is in a range of 7.71~9.31 dB, with a variation of 1.6 dB.
Two composite symmetry structure is proposed in this paper. Based on the integral equation method, the frequency response with large incident angle effect is analyzed. As a result of the numerical analysis, it is shown that the composite symmetry structure with single FSS screen is efficient to stabilize the drift of FSS resonant frequency with the steering of incident angle though transmission loss...
A microtrip-fed semi-elliptical and trapeziform dipole antenna (MFSETDA) which has a small size of (34 mm times 30.2 mm) is presented and designed for ultra-wideband (UWB) communications in this paper. The MFSETDA has large bandwidth covering the frequency from 3.1 to 10.6 GHz, radiation patterns similar to those of conventional dipole antennas. The proposed microtrip-fed antenna is easy to be integrated...
A compact circular slot antenna for ultra-wideband applications is proposed in this letter. The antenna consists of a circular patch and an open annulus, and is fed by coplanar waveguide. The total dimension of the antenna is 30 mmtimes33 mmtimes1.57 mm. The proposed antenna is simulated, fabricated and tested. Results show that a maximum relative impedance bandwidth of more than 130% for |S11| <...
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