Rectangular Array Structure Research Articles

Design of the Gradually Defect Patch Fractal Array Antenna for Unmanned Aerial Vehicle

This paper creatively proposes a new fractal iterative structure of a gradual defect patch and combines it with a rectangular array structure. Aiming at the performance requirements of the UAV system for multi-band compatible antennas, a gradual defect patch fractal array is designed. The radiation performance of the fractal array antenna was simulated by the method of moments, and antenna samples were made and the radiation performance was tested. Both simulation and actual measurement results show that this antenna has a working bandwidth of 5.5 GHz or more, a minimum return loss as low as -44 dB and excellent omnidirectional radiation capability. This antenna is compatible with the GPS system frequency band, Beidou system frequency band, all working frequency bands of the second to fifth generation mobile communication systems and the three working frequency bands of the RFID system, and is expected to be widely used as an unmanned aerial vehicle system antenna.

Analysis of Light Transmittance according to the Array Structure of Collagen Fibers Constituting the Corneal Stroma

Purpose : The size and regular array of the collagen fibers in the corneal stroma have very close correlation with transparency. Simulation was carried out to investigate the change of light transmittance according to the array structure and collagen fiber layer thickness.Methods : The collagen fibers in corneal stroma were arranged in regular hexagonal, hexagonal, square and random shapes with OptiFDTD simulation software, and the light transmittance was analyzed. In square array, the light transmittance according to the density change was confirmed by when the number of collagen fibers in the simulation space was the same and the light transmittance was examined when the number and density of collagen fibers were changedResults : When the number of collagen fibers is the same, the density becomes smaller and the thickness of the fibrous layer becomes thicker in order of arrangement of square, regular hexagonal, random and hexagonal. As a result of measuring the light transmittance by changing the array structure, the light transmittance measured at the detector at the same position was almost similar regardless of the array structure. In the detectors D0, D1, D2 and D3, the maximum transmittance is shown in square, hexagonal and square, regular hexagonal and regular hexagonal array structure, and the minimum transmittance is hexagonal, random, hexagonal and square, and square array structure. However, the difference between the maximum transmittance and the minimum transmittance was almost the same within 1%. When the number of collagen fibers was the same, the light transmittance of the rectangular array structure decreased with increasing fiber layer thickness. And as the thickness increased, the light transmittance decreased more when the number of collagen fibers decreased.Conclusion : Even though the collagen array structure changed, the light transmittance is almost similar regardless of the arrangement structure. However, as the array structure was changed, the thickness of the collagen fiber layer changed, and as the thickness increased, the light transmittance decreased. In other words, the transparency of the corneal stroma is more closely related to the thickness of the fibrous layer than the array of collagen fibers.

Wireless Sensor Network with a Regular, 3D Rectangular Array Structure

A wireless sensor network with a regular, 3D rectangular array structure is studied. The network consists of between 16 and 512 clusters, with between 1 and 5 intelligent sensors per cluster. Analytical expressions are obtained for the probability of failure-free network operation, polling cycle time, and node efficiency. A cyclic polling pipeline algorithm is examined.

Structural Effects in the Electromagnetic Enhancement Mechanism of Surface-Enhanced Raman Scattering: Dipole Reradiation and Rectangular Symmetry Effects for Nanoparticle Arrays

Surface-enhanced Raman scattering (SERS) enhancement factors for Ag and Au sphere array structures are determined by rigorously including dipole reradiation in a T-matrix formalism. Comparisons are made with the more commonly used local field enhancement due to plane-wave excitation, |E(r0;ω)|2|E(r0;ωs)|2 which for zero Stokes shift is |E(r0;ω)|4 to determine the errors associated with this approximation. Substantial errors (factors of 10–100) are found for the peak enhancements at a scattering angle well away from the incident direction, but for backscattering, the errors are negligible. We also present |E|4 enhancement factors using a periodic boundary discrete dipole approximation method for several metal strip array structures, and we show that a certain combination of rectangular array structure and strip properties leads to electromagnetic enhancement factors for mixed photonic-plasmonic resonances that are considerably higher than can be produced with either square arrays or 1-D arrays based on the same particles and spacings.

A wideband smart antenna employing spatial signal processing

A smart antenna with capability of beam steeringin azimuth over a wide frequency band using only spatial sig-nal processing is presented. Filters and tapped-delay networksemployed in conventional wideband linear arrays are avoidedby using a two-dimensional rectangular array structure. Inthis array, only constant real-valued weighting coefficients, re-alized with amplifiers or attenuators, are used to form a de-sired radiation pattern. In order to estimate direction of ar-rival of a wideband signal, the MUSIC algorithm in conjunc-tion with an interpolated array technique is applied. In theinterpolated array technique, a composite covariance matrixis generated, which is a simple addition of covariance matricesof narrowband virtual arrays, being stretched or compressedversions of a nominal array. A working prototype of this wide-band array is presented. Its operation is assessed via full EMsimulations and measurements.