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We examine the hopping dynamics of an artificial spin ice system constructed from colloids on a kagome optical trap array where each trap has two possible states. By applying an external drive from an electric field which is analogous to a biasing applied magnetic field for real spin systems, we can create polarized states that obey the spin-ice rules of two spins in and one spin out at each vertex...
A mechanically-controlled phase shifter of left-handed waveguide is developed for beam-scanning slot array antennas. A delay line using similar periodic structures of right-handed waveguide is also developed for grating lobe suppression of slot array antennas with travelling-wave excitation. The left-handed waveguide is composed of periodic structures as the pair of an inductive iris for shunt inductance...
The printed compound air-fed array (PCAFA) is an improved Fabry-Perot resonator (FPR) antenna, which exhibits better performance than traditional FPR antenna, by means of the non-uniform phase and magnitude of field distribution on aperture are partly compensated in design. In this paper a kind of circularly polarized (CP) PCAFA antenna is proposed and studied, in which the FSS cover is composed of...
Decoupling and matching feeding networks are considerably interested for small wireless terminals to enhance their abilities in the application for MIMO systems. This paper describes various kinds of decoupling and matching feeding networks and derives the formulas for determining the network elements explicitly. Numerical results are presented to ensure the formula for each decoupling and matching...
This paper presents a procedure of numerical code hybridization. It can be effectively used in a fast analysis and synthesis of the field patterns radiated from a phased array antenna. In particular, both low and high frequency methods are employed to simulate simultaneously the strong coupling within an antenna structure and its interactions with electrically large structure existed in its vicinity...
This paper presents a numerical method developed in order to compute the performances of antenna arrays taken into account coupling between radiating elements and edge effects. This method is based on domain decomposition techniques applied to boundary element solver.
This paper proposes a technique to estimate signal parameters for the localization of near-field sources by using concentric circular ring antenna array. The concentric ring array has the property of frequency invariance over certain band of frequencies that can help in localizing wideband sources from received wideband signal. Maximum likelihood (ML) method is applied for parameter estimation of...
In this paper, we propose a phased array antenna which consists of crossed dipole antenna with a reflector as an element antenna. The element antenna is designed by optimizing its parameters. The main and cross polarization characteristics of the right and left side beam scanning of the fabricated 19-element array antenna is measured. Next, the experimental results of the beam scanning characteristics...
Phased array feeds can greatly increase the field of view of interferometric radio telescope arrays. High dynamic range imaging with these arrays requires compensation for drifts in the many receiver-chain gains. A calibration system using surface radiators is proposed for the Australian Square Kilometre Array Path Finder. Design considerations and a proposed system are discussed.
We analyse the sensitivity of a dual-polarized planar connected array with single-ended low noise amplifier (LNA) loading and differential beamforming of the outputs of LNA pairs. Sensitivity is found to depend on the LNA minimum noise figure source admittance and input admittance, with the dependence on the input admittance being relatively weak. Good performance is obtained if these admittances...
This paper describes a newly developed dipole moment (DM) approach, for modeling periodic structures. It is both memory- and time-efficient, and is applicable to arbitrarily shaped elements, whose material properties can also be arbitrary.
This paper provides a radar absorbing method to reduce the radar cross section of the patch array antennas without any loss of antenna performances. The method was based upon the electromagnetic bandgap absorber using a conducting polymer. First, the patch array antenna with a central frequency of 3.0 GHz was designed. Then, the EBG patterns were also designed that had a radar absorbing performance...
The scheme of mono-pulse direction finding is well established. This paper uses a method of electromagnetic simulation to evaluate the direction finding performance of a number of common mono-pulse schemes. The mono-pulse variants include amplitude comparison of mechanically squinted beams, electronic squint and a linear interferometer. The advantage of simulation is that performance and other features...
Placing a phased array at the focus of a paraboloidal reflector increases the area of sky a radio telescope can observe. For a 9×10 chequerboard phased array on a 12 m parabolic dish the available field of view increase from 1 to 36 square degrees at 1.4 GHz. To access this field of view multiple beams are formed. It is impractical to form enough beams to recover all the energy incident on the phased...
An embedded system, based on the field programmable gate array (FPGA) technology is proposed for mitigation of a flawed-array radiation. The current solution includes a genetic algorithm (GA) that finds a new set of the array excitation parameters in case the radiation pattern of the flawed array is unacceptably degraded with respect to the originally designed pattern. A successful real-time mitigation...
The ISM band at 60 GHz provides sufficient bandwidth for wireless transmission of data rates in the Gbps range. To fully utilize this unlicensed frequency range, the design of suitable antennas has to account for application-specific demands in terms of frequency bandwidth and antenna gain. We present a successful implementation, based on a compact patch array approach, meeting realistic requirements...
A base station antenna for WCDMA band (1.920-2.170 GHz) application utilizing an electromagnetic gradient surface (EGS) is proposed. The EGS is applied as a reflector of 4×2 dipole array to tilt the beam with electrically without phase shifters on low-profile structure. Therefore the beam can be tilted with lower complexity, smaller size, and cheaper cost compared to conventional mechanical or electrical...
Limitations to current long range weather radars include reduced coverage of the lower atmosphere, coarse cross range resolution and coarse temporal resolution due to the mechanical scanning. A proposed network of low cost, short range digital radars for monitoring hydrometeor phenomena is described and its potential benefit in providing lower atmospheric coverage is discussed. The benefits of replacing...
In this paper, a phased array antenna for a linearly polarized wave is proposed for mobile satellite communications antennas. An element antenna consists of two loop antennas concentrically located on a dielectric substrate with a reflector and these loop antennas work at dominant and second mode resonant frequencies. Firstly, characteristics of each loop antenna fed by a microstrip transmission line...
This paper describes a numerical approach for the analysis of a reflector antenna system which is fed by a Phased Array Feed. This approach takes mutual interaction effects into account between the antenna array and the low noise amplifiers in the evaluation of the system sensitivity and optimization of the beamformer weights, and can be used when several signal and noise sources are present on the...
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