scholarly journals Decoupling of Multifrequency Dipole Antenna Arrays for Microwave Imaging Applications

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
E. Saenz ◽  
K. Guven ◽  
E. Ozbay ◽  
I. Ederra ◽  
R. Gonzalo
Keyword(s):  
Antenna Array ◽  
Radiation Pattern ◽  
Antenna Arrays ◽  
Mutual Coupling ◽  
Near Field ◽  
Field Measurements ◽  
Dipole Antenna ◽  
Far Field ◽  
Radiated Power ◽  
Near Field Scanning

The mutual coupling between elements of a multifrequency dipole antenna array is experimentally investigated byS-parameter measurements and planar near-field scanning of the radiated field. A multifrequency array with six dipoles is analyzed. In order to reduce the coupling between dipoles, a planar metasurface is placed atop the array acting as superstrate. The mutual coupling of the antenna elements in the absence and presence of the superstrate is presented comparatively. Between 3 and 20 dB mutual coupling reduction is achieved when the superstrate is used. By scanning the field radiated by the antennas and far-field measurements of the radiation pattern, it is observed that the superstrate confines the radiated power, increases the boresight radiation, and reduces the endfire radiation.

scholarly journals Source Localization of EM Waves in the Near-Field of Spherical Antenna Array in the Presence of Unknown Mutual Coupling

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Oluwole John Famoriji ◽  
Thokozani Shongwe
Keyword(s):  
Antenna Array ◽  
Source Localization ◽  
Antenna Arrays ◽  
Mutual Coupling ◽  
Near Field ◽  
Ground Truth ◽  
Doa Estimation ◽  
Measured Data ◽  
Practical Applications ◽  
Spherical Antenna

To obtain an antenna array with isotropic radiation, spherical antenna array (SAA) is the right array configuration. The challenges of locating signals transmitted within the proximity of antenna array have been investigated considerably in the literature. However, near-field (NF) source localization of signals has hitherto not been investigated effectively using SAA in the presence of mutual coupling (MC). MC is another critical problem in antenna arrays. This paper presents an NF range and direction-of-arrival (DoA) estimation technique via the direction-independent and signal invariant spherical harmonics (SH) characteristics in the presence of mutual coupling. The energy of electromagnetic (EM) signal on the surface of SAA is captured successfully using a proposed pressure interpolation approach. The DoA estimation within the NF region is then calculated via the distribution of pressure. The direction-independent and signal invariant characteristics, which are SH features, are obtained using the DoA estimates in the NF region. We equally proposed a learning scheme that uses the source activity detection and convolutional neural network (CNN) to estimate the range of the NF source via the direction-independent and signal invariant features. Considering the MC problem and using the DoA estimates, an accurate spectrum peak in the multipath situation in conjunction with MC and a sharper spectrum peak from a unique MC structure and smoothing algorithms are obtained. For ground truth performance evaluation of the SH features within the context of NF localization, a numerical experiment is conducted and measured data were used for analysis to incorporate the MC and consequently computed the root mean square error (RMSE) of the source range and NF DoA estimate. The results obtained from numerical experiments and measured data indicate the validity and effectiveness of the proposed approach. In addition, these results are motivating enough for the deployment of the proposed method in practical applications.

scholarly journals SIMULATION OF A FLEXIBLE LINEAR GRAPHENE ANTENNA ARRAY ON A PAPER SUBSTRATE

2021 ◽  
Vol 8 ◽  
pp. 307-313
Author(s):  
Alexander G. Cherevko ◽  
Yury V. Morgachev
Keyword(s):  
Antenna Array ◽  
Radiation Pattern ◽  
Antenna Arrays ◽  
Dipole Antenna ◽  
Paper Substrate ◽  
Final Shape ◽  
Flexible Antenna ◽  
Folded Dipole

The article presents an analysis of flexible graphene antenna arrays, which has shown the promise of using a folded dipole antenna as an element of such array. The structure of the flexible folded dipole operating at a frequency of 5,8 GHz on a photo-paper substrate is considered. Simulation yields a gain of 2,53 dBi with a final efficiency of 75% and | S 11| -31,82 dB. The influence of bending on the final shape of the radiation pattern is considered, as well as the value and position of the minimum of the | S 11|. The gain of a linear three-element graphene flexible antenna array based on a folded flexible dipole is 5,78 dBi.

scholarly journals Fast Far-Field Estimation Method by Compact Single Cut Near-Field Measurements for Electrically Long Antenna Array

2018 ◽  
Vol 66 (11) ◽  
pp. 5859-5868 ◽  
Author(s):  
Yoshiki Sugimoto ◽  
Hiroyuki Arai ◽  
Toshiyuki Maruyama ◽  
Masahiko Nasuno ◽  
Masanobu Hirose ◽  
...  
Keyword(s):  
Antenna Array ◽  
Near Field ◽  
Estimation Method ◽  
Field Measurements ◽  
Far Field ◽  
Field Estimation

Linear Pattern Correction Technique for Compensating the Effects of Mutual Coupling and Deformation in Wedge-Shaped Conformal Antenna Arrays

2021 ◽  
Vol 36 (5) ◽  
pp. 533-541
Author(s):  
Adnan Tariq ◽  
Shahid Khattak ◽  
Hina Munsif ◽  
Sohail Razzaq ◽  
Irfanullah Irfanullah
Keyword(s):  
Antenna Array ◽  
Antenna Arrays ◽  
Mutual Coupling ◽  
Dipole Antenna ◽  
Open Circuit ◽  
Main Beam ◽  
Bend Angle ◽  
Linear Pattern ◽  
Correction Technique ◽  
The Individual

In this paper, the effects of mutual coupling and antenna surface deformity in a conformal wedge-shaped antenna array are compensated using a linear pattern correction technique. The problem is formulated to reduce the absolute distance between the actual (simulated) and the desired radiation patterns and to allow for null positioning control. The individual field patterns for the antenna elements are deformed due to changes in mutual coupling and the conformal surface. The deformed patterns of the individual antennas for specific bend angles are stored as lookup tables and interpolated to get the desired radiation pattern at any arbitrary bend-angle. The problem is linearly and quadratically constrained at the null points and performance compared with unconstrained optimization. The proposed solution for diminishing the effect of mutual coupling and surface deformity is independent of main lobe direction, type of individual antenna, array geometry, and spacing between antenna elements. The closed-form results are validated through Computer Simulation Technology (CST) for the wedge-shaped deformed dipole antenna array. The results for the proposed scheme are also assessed with the traditional Open Circuit Voltage Method (OCVM) and show superior compensation for deformity and the mutual coupling effects in conformal beam-forming arrays in terms of main beam direction, position and depth of nulls.

scholarly journals Faulty antenna detection in a linear array using simulated annealing optimization

2020 ◽  
Vol 19 (3) ◽  
pp. 1340
Author(s):  
Navaamsini Boopalan ◽  
Agileswari K. Ramasamy ◽  
Farrukh Hafiz Nagi
Keyword(s):  
Simulated Annealing ◽  
Radiation Pattern ◽  
Antenna Arrays ◽  
Communication Systems ◽  
Linear Array ◽  
Near Field ◽  
Optimization Method ◽  
Random Permutation ◽  
Far Field ◽  
Planar Array

<span lang="EN-US">Sonar, radar and communication systems solely depend on antenna arrays for signal attainment. These arrays are capable of producing directional signals which can be steered in a certain direction. Faulty elements in an array will result in distorted radiation pattern with increased sidelobe levels.  Far-field faulty antenna detection is necessary due to the near field repairing at complex systems like spacecraft. This paper proposes simulated annealing (SA) optimizing method to find the faulty element’s location in a linear array. In this study, a Chebyshev array is presented with the SA optimization method to detect faulty element location with a random permutation of failure locations tested. This method can successfully detect faulty antenna in a linear array. Even though, this method is developed for linear array it can easily be adapted to a planar array.</span>

scholarly journals Efficient Planar Near-field Measurements for Radiation Pattern Evaluation by a Warping Strategy

IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Maria Antonia Maisto ◽  
Giovanni Leone ◽  
Adriana Brancaccio ◽  
Raffaele Solimene
Keyword(s):  
Radiation Pattern ◽  
Near Field ◽  
Field Measurements
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