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Radiation Patterns of an Arbitrarily Oriented VLF Curtain array in an Anisotropic Magnetoplasma

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2023年第7期71卷 5885-5894页

作者： He, Tong Zeng, Hui Ran Li, Kai Zhejiang Lab Res Inst Intelligent Networks Hangzhou 311121 Zhejiang Peoples R China Xidian Univ Hangzhou Inst Technol Hangzhou 311200 Peoples R China Xidian Univ Sch Elect Engn Xian 710071 Peoples R China Zhejiang Univ Coll Informat Sci & Elect Engn Hangzhou 310027 Zhejiang Peoples R China

In this article, we propose a theoretical method for calculating the radiation patterns of a very low-frequency (VLF: 3-30 kHz) curtain array immersed in an anisotropic magnetoplasma. As the arrays formed by multiple VLF linear antennas may become a potential scheme for VLF space-borne transmissions, figuring out the radiation pattern of such arrays is essential to the performance evaluation or efficiency improvement of practical VLF space-borne transmitting systems. The analytical expression for the VLF field excited by an electric dipole is first given at arbitrary orientations. By considering the influence of current nonuniformity and mutual coupling, the total radiation field of the array is obtained for both near- and far-zone cases, and the array factor is derived under the far-zone condition. Computations and analyses show that variations in the current phase difference or electrical separation will cause certain changes to the directivity of the array in the near zone, while the radiation pattern in the far zone mainly follows the direction of the geomagnetic field. It is also found that despite the total field of an array can be enhanced by increasing the number of elements, the marginal gain on the field amplitude is descendant as the element number keeps increasing. Moreover, due to the larger wave attenuation in the propagation direction vertical to the magnetic field, the radiation ability of the array will gradually decrease when the geomagnetic inclination angle becomes larger.

关键词： Anisotropic magnetoplasma array factor curtain array radiation pattern very low frequency (VLF)

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Recovery of Failed Element Signal with a Digitally Beamforming Using Linear Symmetrical array Antenna

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JOURNAL OF INFORMATION SCIENCE AND ENGINEERING 2016年第3期32卷 611-624页

作者： Klhan, Shafqat Ullah Qureshi, Ijaz Mansoor Shoaib, Bilal Naveed, Aqdas ISRA Univ Sch Engn & Appl Sci Islamabad 44000 Pakistan Air Univ Dept Elect Engn Islamabad 44000 Pakistan Int Islamic Univ Dept Elect Engn Islamabad 44000 Pakistan

An antenna array element failure problem is one of the practical and challenging issues in the field of adaptive beamforming. The complete radiation pattern of the array is distorted when any one of the elements fails. Sidelobes level increases, nulls are shifted and null depth is also decreased tremendously. In order to mitigate the problem, we have given a new and easy approach coined as conjugate symmetry approach of the array. In this, the failed element is given a conjugate of the output from its symmetrical counterpart element in the array. The Classical Dolph-Chebyshev and Taylor pattern are taken as the test antenna. The simulation results of both patterns show the validity and presentation of the proposed approach.

关键词： linear symmetrical array failure correction array factor beamforming sidelobes level

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A compact and high gain substrate integrated horn array antenna system

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2019年第2期61卷 343-348页

作者： Ramadurgakar, Ameya Song, Heather H. Univ Colorado Dept Elect & Comp Engn 1420 Austin Bluffs Pkwy Colorado Springs CO 80918 USA

In this paper, a novel compact, lightweight and high gain array antennae system is demonstrated which is based on substrate integrated dielectric filled waveguide concepts. It is a planar design which can be easily fabricated with a common two-layer substrate. The overall goal was to have a high gain so that this array antenna could be potentially used in autonomous unmanned aerial vehicle systems for collision avoidance. An initial model was designed, simulated and fabricated and, upon evaluation, was further modified to achieve a higher performance specification. Additionally, the design can be easily and inexpensively fabricated using standard substrates with a rapid prototyping platform. A two element array resulted in a simulated gain of 9.6 dB with a radiation pattern which had a maximum lobe between a broadside and an end-fire. This was with a low loss substrate such as Rogers RT duroid 5880. For the design, a low dissipation factor material is preferable as it minimizes losses and also increases compactness of the entire antenna array.

关键词： antenna array antenna array factor directivity gain horn antenna radar cross section (RCS) radar range equation (RRE) radiation pattern S-11 substrate integrated waveguides three antenna gain measurement unmanned aerial vehicle waveguide

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Sideband radiation reduction exploiting pattern multiplication in directive time-modulated linear arrays

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IET MICROWAVES ANTENNAS & PROPAGATION 2012年第2期6卷 214-222页

作者： Poli, L. Rocca, P. Massa, A. Univ Trento Eledia Res Grp Dept Informat Engn & Comp Sci I-38123 Trento Italy

The reduction of the power losses in the sideband radiation of directive time-modulated linear arrays is addressed. The approach is based on the optimisation of the pulse sequence modulating the static excitations of the array elements to exploit pattern multiplication effects such that the sideband level of the harmonic pattern term related to the array factor is balanced by the element pattern distribution. A set of representative numerical results is reported and discussed to illustrate the potentialities and the limitations of the proposed approach.

关键词： Economic Resources distribution (property) power loss array Element linear arrays array factor directive

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Mixed microwave-digital and multi-rate approach for wideband beamforming applications using 2-D IIR beam filters and nested uniform linear arrays

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MULTIDIMENSIONAL SYSTEMS AND SIGNAL PROCESSING 2018年第2期29卷 703-718页

作者： Ariyarathna, Viduneth Madanayake, Arjuna Agathoklis, Panajotis Bruton, Len T. Univ Akron Dept Elect & Comp Engn Akron OH 44325 USA Univ Victoria Dept Elect & Comp Engn Victoria BC Canada Univ Calgary Dept Elect & Comp Engn Calgary AB T2N 1N4 Canada

The presented work explores novel methods for synthesizing approximately frequency independent array factors at lower hardware complexity for wideband beamforming applications. The proposed approach employs 2-D infinite impulse response (IIR) digital beam filters together with nested uniform linear arrays (ULAs). The array is designed to have multiple levels of nesting. Each level of nesting consists of a ULA covering a temporal subband of the incident wideband signal. The use of nested arrays provides the required aperture size using a smaller number of elements compared to using a single ULA to capture the entire wideband signal. The use of different levels of nesting allows the operation of the digital processor for each sub-band at different clock rates. This is a hierarchical approach that saves both digital VLSI hardware and power consumption. The 2-D IIR digital beam filters that process each subband signal from each of the nested subarray achieves wideband beamforming. Simulations illustrate approximately frequency independent passbands as required in wideband beamforming.

关键词： broadband signal Beamforming Butyl rubber Filters subband subband signal aperture size Logic arrays array factor nesting uniform linear arrays broadband

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Imaging and Steering Unidirectional Emission from Nanoantenna array Metasurfaces

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ACS PHOTONICS 2016年第2期3卷 286-292页

作者： Lindfors, Klas Dregely, Daniel Lippitz, Markus Engheta, Nader Totzeck, Michael Giessen, Harald Univ Stuttgart Phys Inst 4 Pfaffenwaldring 57 D-70550 Stuttgart Germany Univ Stuttgart Res Ctr SCoPE Pfaffenwaldring 57 D-70550 Stuttgart Germany Max Planck Inst Solid State Res Heisenbergstr 1 D-70569 Stuttgart Germany Univ Cologne Dept Chem Luxemburger Str 116 D-50939 Cologne Germany Univ Bayreuth Dept Phys Univ Str 30 D-95447 Bayreuth Germany Univ Penn Dept Elect & Syst Engn 200 South 33rd StESE 203 Moore Philadelphia PA 19104 USA Carl Zeiss Corporate Res & Technol Carl Zeiss Str 22 D-73447 Oberkochen Germany

In radiofrequency antenna engineering, the array factor made long-distance communication with steerable transmission and receiving possible. At optical frequencies, low-loss signal transmission via free space by using nano antennas is still in its infancy. Here, we suggest applying the array factor to the optical frequency regime by shaping the radiation pattern of plasmonic metasurfaces featuring nano antenna arrays. We arrange dipolar gold nanoantennas operating at 785 nm wavelength in wavelength-sized arrays and control the phase that drives the antenna elements. We obtain collimated and unidirectional radiation from this metasurface upon illumination with circularly polarized light, which is not prone to major losses as in common plasmonic waveguide structures. We furthermore demonstrate switching the unidirectional emission to opposite directions with additional beamsteering by modifying the array factor. Our experiment corroborates the evidence for spin orbit coupling between the helicity of light and suitably designed plasmonic metasurfaces, which can exhibit the spin-Hall effect for light.

关键词： optical nanoantenna array factor metasurface luminescent imaging beam steering

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Analysis of Photonics-Based RF Beamforming With Large Instantaneous Bandwidth

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2017年第23期35卷 5010-5019页

作者： Ye, Xingwei Zhu, Dan Zhang, Yamei Li, Simin Pan, Shilong Nanjing Univ Aeronaut & Astronaut Minist Educ Key Lab Radar Imaging & Microwave Photon Nanjing 211106 Jiangsu Peoples R China

Since the photonics-based true time delay could significantly broaden the instantaneous bandwidth of a phased antenna array system, solutions utilizing wideband signals could be enabled to considerably enhance the functionality and performance of RF systems. To investigate the features of the wideband beamforming, a comprehensive theoretical model is developed in this paper to analyze the photonics-based broadband beamforming network for uniform linear arrays. In the proposed model, the performance of the beamforming network over the operational frequency band is intuitively depicted through a two-dimensional spatial-temporal frequency response, in which both the spatial frequency (or the corresponding observation angle) and the temporal frequency are adopted as independent variables. In addition, cross correlation of the original signal and the signal that undergoes the beamforming network is calculated to define a wideband pattern and a new figure of merit, so that the waveform-dependent overall response over a large bandwidth can be evaluated. Based on the theoretical model, a time-domain method for pattern measurement is proposed and experimentally demonstrated, which offers the coincident result as the frequency-domain method but is more convenient to be conducted. Numerical results of several typical photonics-based beamforming structures are presented to investigate the impact of nonidealities on the two-dimensional response and the proposed figure of merit.

关键词： array factor broadband beamforming correlation reception optical true time delay

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Optimization of Far-Field Patterns Based on Direct Synthesis Results

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2023年第12期71卷 9956-9961页

作者： Xiao, Gaobiao Wang, Xiaocheng Zang, Ting Shanghai Jiao Tong Univ State Key Lab Radio Frequency Heterogeneous Integr Shanghai 200240 Peoples R China

Electromagnetic radiation patterns can be directly synthesized using the propagation modes corresponding to a linear source or a rectangular current sheet. This communication shows that, although the directly synthesized patterns usually have high sidelobe levels and large ripples in the main beams, they can be used as very good initial patterns for further optimization. By tracing the extrema of the radiation pattern flexibly, the sidelobe levels and the ripples in the main beams can be effectively controlled. Since the number of the extrema is approximately equal to the number of degrees of freedom of the far field, the algorithm converges monotonically. Numerical examples validate the hybrid optimization algorithm.

关键词： Manganese Optimization Antenna radiation patterns Antenna arrays Harmonic analysis Satellite broadcasting Interpolation Antenna array synthesis array factor number of degrees of freedom (NDF) radiation field

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Recalculating linear array antennas to compensate for failed elements while maintaining fixed nulls

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JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS 1999年第3期13卷 397-412页

作者： Lozano, MV Rodríguez, JA Ares, F Univ Santiago de Compostela Fac Fis Grp Sistemas Radiantes Dept Fis Aplicada Santiago De Compostela 15706 Spain

A new technique for the synthesis of linear array antenna patterns is presented. This technique allows to fix nulls in prescribed directions, to simulate the presence of failed elements and to obtain power patterns when both situations occur at the same time. These patterns are synthesized by finding the optimal configuration of the array factor roots using the simulated annealing technique. Examples of fixing nulls and/or failed elements in both sum and flat-topped beam patterns are presented.

关键词： Pattern synthesis Sidelobe level Algorithm linear antenna arrays algorithms pattern synthesis Antenna arrays linear arrays array factor Fixed

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Application of Ant Colony Optimization Algorithm to Pattern Synthesis of Uniform Circular Antenna array

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APPLIED COMPUTATIONAL ELECTROMAGNETICS SOCIETY JOURNAL 2015年第8期30卷 810-818页

作者： Zare, Amir Saman Baghaiee, Saba Tech Univ Darmstadt Darmstadt Germany Ershade Alborz Univ Tehran Informat Technol Engn Dept Tehran Iran

The radiation pattern of the antenna arrays is most important problem in communications technology. In this paper, the optimization of uniform circular antenna array is efficiently solved by ant colony optimization (ACO) Method. The proposed method of optimization is used to determine the suitable cost function which leads to achieve the maximum reduction in side lobe level and provide the maximum directivity towards the direction. To optimize the desired antenna array pattern also one parameter is considered to be optimized which is the angular position of each element.

关键词： Ant colony optimization array factor directivity side lobe level uniform circular antenna array

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