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[IEEE 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Cartagena des Indias (2018.9.10-2018.9.14)] 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Antenna Pattern Effects in a Low Sidelobe Circularly Polarized Planar Array Due to Element Errors
摘要： Random amplitude and phase errors at the elements of a phased array antenna cause elevated sidelobe levels. Formulas for predicting the sidelobe levels based on the error statistics are well known. These same random errors also cause an error in the axial ratio of a circular polarized array. This paper presents some new expressions for the change in axial ratio as a function of the random errors.
关键词： antenna arrays,axial ratio,planar arrays,circular polarization,array errors,crossed dipoles
更新于2025-09-23 15:22:29
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SYNTHESIS OF SPARSE OR THINNED LINEAR AND PLANAR ARRAYS GENERATING RECONFIGURABLE MULTIPLE REAL PATTERNS BY ITERATIVE LINEAR PROGRAMMING
摘要： It is shown in this paper that the problem of reducing the number of elements for multiple-pattern arrays can be solved by a sequence of reweighted (cid:2)1 optimizations under multiple linear constraints. To do so, conjugate symmetric excitations are assumed so that the upper and lower bounds for each pattern can be formulated as linear inequality constraints. In addition, we introduce an auxiliary variable for each element to define the common upper bound of both the real and imaginary parts of multiple excitations for different patterns, so that only linear inequality constraints are required. The objective function minimizes the reweighted (cid:2)1-norm of these auxiliary variables for all elements. Thus, the proposed method can be efficiently implemented by the iterative linear programming. For multiple desired patterns, the proposed method can select the common elements with multiple set of optimized amplitudes and phases, consequently reducing the number of elements. The radiation characteristics for each pattern, such as the mainlobe shape, response ripple, sidelobe level and nulling region, can be accurately controlled. Several synthesis examples for linear array, rectangular/triangular-grid and randomly spaced planar arrays are presented to validate the effectiveness of the proposed method in the reduction of the number of elements.
关键词： thinned arrays,planar arrays,reconfigurable arrays,Sparse arrays,iterative linear programming,linear arrays,multiple patterns
更新于2025-09-23 15:21:21
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A Wideband Planar Aperture Array Using Interconnected Crossed Rings
摘要： A 5:1 frequency bandwidth aperture array antenna based on a new planar structure is reported. Dual polarization is implemented with high cross-polarization discrimination over ±45? scan angle from zenith. It is a low-loss cost effective approach using minimum dielectric materials. In the proposed planar antenna array design, a mutual coupled interconnected ring structure is used which extends the operational frequency band to the region where the element separation can be considerably greater than half a wavelength, unlike the previously reported interconnected array structures. Hence the total number of elements can be reduced for a speci?ed aperture size. The dual polarization have coincident-phase centers and in the implemen-tation reported here two low noise ampli?ers on the same board are integrated with a pair of dual polarized elements to form an active array. A 10 by 10 element array prototype of the design has been manufactured and the measured results con?rm it as a low cost, high performance front-end solution.
关键词： Aperture antennas,Phased arrays,Planar arrays,Radio astronomy
更新于2025-09-23 15:21:21
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Circularly Polarized T-Shaped Slot Waveguide Array Antenna for Satellite Communications
摘要： A novel circularly polarized (CP) waveguide slot array for satellite communications is proposed. The antenna features a unique feeding network and a unit cell that consists of a pair of simple T-shaped waveguide slots. The proposed configuration not only eliminates grating lobes, which are often seen in conventional waveguide slot arrays, but also simplifies the fabrication process without any sacrifice in the performance, while also allowing scalability. A prototype 6×8 array antenna is designed at 29.5 GHz, and fabricated by dip brazing. A high gain of 21.9 dBi and a -10 dB impedance bandwidth of 1 GHz are achieved, with an axial ratio of 1.3 dB without any grating lobes. The measured results are in very good agreement with the simulated results.
关键词： circular polarization,antenna arrays,Slot antennas,waveguide antennas,planar arrays
更新于2025-09-16 10:30:52
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Fast Analysis of Metasurfaces through Temporal Coupled-mode Theory
摘要： In this article, a rigorous temporal coupled-mode theory (CMT) formalism is developed, to analyze metasurface (MTS)-based structures. Such MTSs are generally rather complex, requiring extensive, full-wave simulations. To facilitate their design and minimize the associated computational demand, the CMT solves a small linear system of equations, fed by the results of certain much simpler and less time- and memory-consuming eigenvalue problems. The proposed method is versatile and offers an initial, valuable estimation of the structure’s frequency response, which may be used as a guideline for the ?nal MTS ?ne tuning. As proof of concept, split-ring resonator (SRR) MTSs coupled to microstrip lines are analyzed, and their response is compared with the full-wave ?nite-element method (FEM) results.
关键词： Coupled-mode analysis,planar arrays,metasurfaces (MTSs),electromagnetic metamaterials
更新于2025-09-16 10:30:52
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Design of Low-Complexity 3-D Underwater Imaging System With Sparse Planar Arrays
摘要： The development of a real-time 3-D underwater imaging system with a planar array is restricted by the huge hardware cost and computational burden associated with the large number of elements required. In this paper, a new design of low-complexity 3-D underwater imaging system is proposed, involving two key parts: a special sparse array with low hardware cost and an ef?cient beamforming with low computational burden. Especially, the simulated annealing algorithm is optimized based on distributed and parallel subarray (DPS) beamforming and results in fewer active elements than existing methods. To improve the computational ef?ciency especially for sparse arrays, an optimized DPS beamforming is presented with the pruning fast Fourier transform technology. To test the validity of the design, a real system based on the proposed methods was devised and employed in the lake and sea trials. The experiment results demonstrate that the low-complexity 3-D underwater imaging system can provide a satisfactory imaging quality.
关键词： sparse planar arrays,underwater acoustic imaging,sonar signal processing,simulated annealing (SA) algorithm,3-D sonar systems
更新于2025-09-09 09:28:46
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[IEEE 2017 51st Asilomar Conference on Signals, Systems, and Computers - Pacific Grove, CA, USA (2017.10.29-2017.11.1)] 2017 51st Asilomar Conference on Signals, Systems, and Computers - Frequency invariant beamforming for arbitrary planar arrays
摘要： In this paper, we present the adaptation to the least-square solution for frequency invariant beamforming to arbitrary planar arrays. This formulation is easily steerable thanks to the decoupling of spatial and spectral constraints. This is achieved with a basis of spherical harmonics polynomials, which parametrize the array response in a term dependent on frequency and a term dependent on the array geometry. Furthermore, the parametrization of the array response Bessel functions decouples the frequency term, which becomes independent of the geometry of the planar array, and allows steering in azimuth and elevation independently. The planar array response is approximated using virtual sensor modeling, which transform any two dimensional planar array in a virtual linear sensors, where azimuth and elevation are separable and can be steered independently.
关键词： frequency invariant beamforming,virtual sensor modeling,planar arrays,spherical harmonics
更新于2025-09-09 09:28:46