scholarly journals Low Discrepancy Sparse Phased Array Antennas

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7816
Author(s):  
Travis Torres ◽  
Nicola Anselmi ◽  
Payam Nayeri ◽  
Paolo Rocca ◽  
Randy Haupt
Keyword(s):  
Mathematical Formulation ◽  
Sampling Technique ◽  
Numerical Results ◽  
Field Pattern ◽  
Triangular Grid ◽  
Sparse Arrays ◽  
Phased Array Antennas ◽  
Planar Arrays ◽  
Planar Array ◽  
Far Field Pattern

Sparse arrays have grating lobes in the far field pattern due to the large spacing of elements residing in a rectangular or triangular grid. Random element spacing removes the grating lobes but produces large variations in element density across the aperture. In fact, some areas are so dense that the elements overlap. This paper introduces a low discrepancy sequence (LDS) for generating the element locations in sparse planar arrays without grating lobes. This nonrandom alternative finds an element layout that reduces the grating lobes while keeping the elements far enough apart for practical construction. Our studies consider uniform sparse LDS arrays with 86% less elements than a fully populated array, and numerical results are presented that show these sampling techniques are capable of completely removing the grating lobes of sparse arrays. We present the mathematical formulation for implementing an LDS generated element lattice for sparse planar arrays, and present numerical results on their performance. Multiple array configurations are studied, and we show that these LDS techniques are not impacted by the type/shape of the planar array. Moreover, in comparison between the LDS techniques, we show that the Poisson disk sampling technique outperforms all other approaches and is the recommended LDS technique for sparse arrays.

scholarly journals Multiobjective Optimization Using Modified Binary PSO for Reduction of Sidelobe Level of the Thinned Array Antenna

2021 ◽  
Vol 11 (4) ◽  
pp. 2715-2725
Author(s):  
A. Gayatri ◽  
M. Surendra Kumar ◽  
A.M. Prasad
Keyword(s):  
Antenna Array ◽  
Cutting Planes ◽  
Array Antenna ◽  
Field Pattern ◽  
Far Field ◽  
Sigmoid Function ◽  
Efficient Communication ◽  
Planar Array ◽  
Binary Pso ◽  
Far Field Pattern

To design an efficient communication system, controlling the energy present in the side lobes of the far-field pattern is essential with a considered antenna array. This paper discussed one method for synthesizing a thin antenna array for optimizing three objectives simultaneously. They are several active elements, peak SLL and FNBW. All these objectives are in contrast in nature. This multi-objective technique furnishes appreciable flexibility for any specified application. A planar array antenna of 20X10 and 10X10 is synthesized using modified BPSO and in the position updating equation, a modified sigmoid function is used, including spread distance. Numerical results state that MBPSO performs well, and the array antenna of 20X10 with 54% filled aperture (108 elements) produces maximum PSLL and FNBW of -19.28dB and 280 in the remaining ∅ plane, respectively. The pattern representation in the far-field at three cutting planes with low PSLL’s of -20dB.Whereas 10X10 planar array antenna with 52% thinning percentage produces the best PSLL of -22.04 dB and -23.44 dB in ∅=00 & 900principal planes, respectively. The FNBW has observed in two planes is around 310. And also achieved a compromised solution of PSLL and FNBW of -19.28 dB and 270, respectively.

scholarly journals Thermos Array: Two-Dimensional Sparse Array with Reduced Mutual Coupling

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Lei Sun ◽  
Minglei Yang ◽  
Baixiao Chen
Keyword(s):  
Closed Form ◽  
Degrees Of Freedom ◽  
Mutual Coupling ◽  
Doa Estimation ◽  
Two Dimensional ◽  
Spatial Smoothing ◽  
Planar Arrays ◽  
Half Wavelength ◽  
Planar Array ◽  
Small Spacing

Sparse planar arrays, such as the billboard array, the open box array, and the two-dimensional nested array, have drawn lots of interest owing to their ability of two-dimensional angle estimation. Unfortunately, these arrays often suffer from mutual-coupling problems due to the large number of sensor pairs with small spacing d (usually equal to a half wavelength), which will degrade the performance of direction of arrival (DOA) estimation. Recently, the two-dimensional half-open box array and the hourglass array are proposed to reduce the mutual coupling. But both of them still have many sensor pairs with small spacing d, which implies that the reduction of mutual coupling is still limited. In this paper, we propose a new sparse planar array which has fewer number of sensor pairs with small spacing d. It is named as the thermos array because its shape seems like a thermos. Although the resulting difference coarray (DCA) of the thermos array is not hole-free, a large filled rectangular part in the DCA can be facilitated to perform spatial-smoothing-based DOA estimation. Moreover, it enjoys closed-form expressions for the sensor locations and the number of available degrees of freedom. Simulations show that the thermos array can achieve better DOA estimation performance than the hourglass array in the presence of mutual coupling, which indicates that our thermos array is more robust to the mutual-coupling array.

Effect of transverse mode structure on the far field pattern of metal-metal terahertz quantum cascade lasers

2008 ◽  
Vol 104 (12) ◽  
pp. 124513 ◽  
Author(s):  
P. Gellie ◽  
W. Maineult ◽  
A. Andronico ◽  
G. Leo ◽  
C. Sirtori ◽  
...  
Keyword(s):  
Quantum Cascade Lasers ◽  
Transverse Mode ◽  
Field Pattern ◽  
Far Field ◽  
Mode Structure ◽  
Quantum Cascade ◽  
Metal Metal ◽  
Far Field Pattern ◽  
Cascade Lasers

Far-field patterns of line sources mounted between four-dielectric substrates

1992 ◽  
Vol 70 (2-3) ◽  
pp. 173-178 ◽  
Author(s):  
Ioanna Diamandi ◽  
Costas Mertzianidis ◽  
John N. Sahalos
Keyword(s):  
Remote Sensing ◽  
Line Source ◽  
Dielectric Substrate ◽  
Microstrip Antennas ◽  
Field Pattern ◽  
Substrate Thickness ◽  
Far Field ◽  
Dielectric Substrates ◽  
Field Patterns ◽  
Far Field Pattern

The far-field pattern characteristics of line sources lying between the slabs of a four-dielectric substrate configuration are presented. The patterns are calculated for several cases of the substrate thickness as well as for several line-source locations. The considerations that are made give useful applications in remote sensing and microstrip antennas.

scholarly journals Second harmonic generation from 3D nanoantennas: on the surface and bulk contributions by far-field pattern analysis

2011 ◽  
Vol 19 (27) ◽  
pp. 26752 ◽  
Author(s):  
Alessio Benedetti ◽  
Marco Centini ◽  
Mario Bertolotti ◽  
Concita Sibilia
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Pattern Analysis ◽  
Second Harmonic ◽  
Field Pattern ◽  
Far Field ◽  
Far Field Pattern

scholarly journals Integrated circular optical phased array

2021 ◽  
Vol 255 ◽  
pp. 01004
Author(s):  
Qiankun Liu ◽  
Tom Smy ◽  
Ahmad Atieh ◽  
Pavel Cheben ◽  
Alejandro Sánchez-Postigo ◽  
...  
Keyword(s):  
Phased Array ◽  
Field Pattern ◽  
Antenna Element ◽  
Sidelobe Suppression ◽  
Integrated Optical ◽  
Optical Phased Arrays ◽  
Optical Phased Array ◽  
Element Array ◽  
The Individual ◽  
Far Field Pattern

Existing OPAs are typically based on 2D rectangular arrays or 1D linear arrays. Both approaches present a limited field-of-view (FOV) due to the presence of the grating lobes when the element spacing is larger than λ/2. To address the need for an increased steering range, we propose a new design strategy of an OPA system utilizing a 2D circular phased array, with a substantially increased FOV. We present a circular OPA using a demonstrated antenna element design, with an 820-element array. A steering range ΩSR calculated as a solid angle of 0.51π sr, and an angular beamwidth of 0.22°, was achieved. The array exhibits a sidelobe suppression larger than 10 dB, and a FOV of 2π sr. Although the performance is limited by the far field pattern of the individual antenna we chose, our circular OPA achieved, to the best of our knowledge, the largest steering range reported to date compared to the state-of-the-art integrated optical phased arrays reported in literature.

scholarly journals Reconstruction of the near-field distribution in an X-ray waveguide array

2017 ◽  
Vol 50 (3) ◽  
pp. 701-711 ◽  
Author(s):  
Qi Zhong ◽  
Lars Melchior ◽  
Jichang Peng ◽  
Qiushi Huang ◽  
Zhanshan Wang ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Field Distribution ◽  
Phase Retrieval ◽  
Near Field ◽  
Field Pattern ◽  
Waveguide Array ◽  
X Ray ◽  
Field Patterns ◽  
Thickness Variations ◽  
Far Field Pattern

Iterative phase retrieval has been used to reconstruct the near-field distribution behind tailored X-ray waveguide arrays, by inversion of the measured far-field pattern recorded under fully coherent conditions. It is thereby shown that multi-waveguide interference can be exploited to control the near-field distribution behind the waveguide exit. This can, for example, serve to create a secondary quasi-focal spot outside the waveguide structure. For this proof of concept, an array of seven planar Ni/C waveguides are used, with precisely varied guiding layer thickness and cladding layer thickness, as fabricated by high-precision magnetron sputtering systems. The controlled thickness variations in the range of 0.2 nm results in a desired phase shift of the different waveguide beams. Two kinds of samples, a one-dimensional waveguide array and periodic waveguide multilayers, were fabricated, each consisting of seven C layers as guiding layers and eight Ni layers as cladding layers. These are shown to yield distinctly different near-field patterns.

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