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Under the fully matched condition, we present microwave-circuit simulation results of subwavelength imaging by a slab composed of L, C loaded transmission-line media with a source in it., and we have found that, although the single-interface lens composed of an negative refractive index medium and a positive refractive index medium are not involved in the growth of evanescent wave to achieve perfect...
To analyze a dielectric medium encapsulation, round cylinder monopole plasma antenna which is more practicable and applicable, the finite-difference time-domain (FDTD) method is implemented. Influences of operating frequency and dielectric tube permittivity on the far-field antenna radiation intensity are investigated and evaluated. Numerical results indicate that the radiated power plays as a function...
In this paper, the multidomain pseudospectral time-domain (MPSTD) algorithm is applied to model the curved waveguide structures. In order to improve the stability of the MPSTD method, the design of a filtering procedure is discussed for corner singularities. By calculating the resonant frequencies and S-parameters of the waveguide structures, numerical results indicate that the MPSTD method can achieve...
Rugged indeterminacy of natural scenes and the characteristic of random distribution of various media are the difficulties to realize fast simulation of echo-wave signals and imaging of synthetic aperture radar. An echo-wave signal simulation method of SAR is presented. A simulation model is constructed using a real DEM. Based on the scattering model expressions of a random roughness surface and the...
In this paper, two kind of microwave absorbers based on local resonance of artificial periodic structures i.e. metamaterials. When irradiated by plane wave with adaptive polarization, there will be electric or magnetic local resonance in the metamaterials. To absorb the microwave energy been reflected, resistive sheets are used like conventional Salisbury screen. The absorber based on electric resonance...
The paper studies the path loss models of the wideband channels at 2.3 GHz, 2.6 GHz and 3.5 GHz which are released by ITU-R(International Telecommunication Union-Radio communications) for the new generation radio network IMT-Advanced in a typical outdoor suburban environment of Shanghai, China. A channel measurement system for these frequency bands was developed; based on the measurement data, empirical...
A finite-difference time-domain approach for electromagnetic scattering characteristic from a 2-D ship model above the 1-D randomly rough sea surface is presented. Taking the composite scattering of rough sea surface and infinitely long cylinder as an example, the angular distribution of the scattering coefficient with different incident angles is calculated and it shows good agreement with the numerical...
Considering the features of UAV (unmanned air vehicle) networking in near-space, such as low network performance, ineffective communication capability of UAV clusters and the difficulty to manage UAV while it is out of sight, this paper proposes a space-Earth-based integrated - "Calculate on the ground, Adjust in the space" thought to design a "clustering algorithm of UAV networking...
Study on the electronic countermeasure (ECM) methods and techniques against synthetic aperture radar (SAR) are becoming one of the important topics in the field of electronic warfare (EW). A computer simulation of ECM effect based on ground moving target indication (GMTI) using single-antenna is proposed in this paper. The model used in the simulation includes real-time active coherent jamming model...
The following topics are dealt with: antennas and related topics; propagation and related topics; EM theory and related topics; computational electromagnetics; and electromagnetic compatibility and related topics.
This paper presents an implementation of a real-time FFT processor based on FPGA, which uses the radix-4 DIF (decimation-in-frequency) algorithm. Five stages of radix-4 butterflies are used to make up of a pipeline to compute the 1024-point complex FFT. The FFT processor can operate at 164 MHz and compute a 1024-point FFT at 6.225 mus when operating on the device of Xilinx Virtex II Pro 70. This will...
Ultra wideband (UWB) system operates by transmitting signals over a very wide band of spectrum, so there must be the problem of coexistence of UWB with other radio services besides the spread spectrum communication system. By designing the simulation models of UWB system and spread spectrum system which is used more broadly, the simulation experiments has been taken on the performance of spread spectrum...
Phase-switched screen (PSS) is a novel technique proposed recently for radar cross section (RCS) reduction. Different from conventional radar absorbing materials (RAM), PSS technique modulates in phase the scattered waves using a switching signal and redistributes the scattered energy in a wider band, enabling dynamic control of RCS.
A four column Smart antenna array fed by a 4x4 Butler matrix augmented by a variable beam shaping network has been designed and simulated. It is demonstrated that using only three phase shifters within the beam shaping network provides dynamic beam flexibility including: four narrow switched beams, a right shaped beam, a left shaped beam and a broad broadcast channel beam. The shaped beams concentrate...
The digital radiometer detector (DRD) is a digital signal processing detector, of which the essential elements hardware consist of a high-speed, high-resolution analog-to digital converter (ADC). A practical ADC will have an uneven step size (differential nonlinearity) between quantization thresholds, and changes the probability distribution of the sampled data and further distorts the input signal,...
For radio access systems based on time division duplex (TDD) mode, like the time division synchronous code multiple access (TD-SCDMA) radio system, frame synchronization is a fundamental feature to minimize interference and therefore optimize the offered traffic capacity. In particular, sub-frame synchronization ensures that uplink and downlink transmission directions are positioned. In this paper...
Irregular-repeat-accumulate (IRA) codes are random-like codes having extremely good performance over AWGN channel. They can be viewed as special kinds of LDPC codes in the way their parity-check matrix are sparse. Like LDPC codes, they can be decoded using the messages-passing algorithm efficiently, while the existence of short length circles in their corresponding factor graph representation has...
A resistor-capacitor (RC) network model of moist substance are presented. FL-based algorithm is applied to compute the dielectric properties of the model, which is very general, and could be applied to two-phase (conductor-insulator) materials. Simulating results show that the dielectric relaxation process of moist substances is non-Debye, and relaxation times of the RC network are obtained by curve...
We propose an adaptive transmit power allocation (ATPA) scheme for vertical Bell laboratories layered space-time (V-BLAST) system in the presence of channel state information (CSI) imperfection. The proposed ATPA scheme is aimed at minimizing the bit error rate (BER). At the transmitter, subjected to the total transmit power constraint, the proposed ATPA scheme is used to allocate proper power for...
A combination of the two-point linear interpolation and the optimal sampling interpolation (OSI) technique is used to reconstruct the primary pattern of reflector antennas, with the efficiency being demonstrated by an example.
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