Wideband symmetric near‐field radiation pattern of sleeve dipole antenna by connecting additional ferrite‐loaded wire

2015 ◽  
Vol 51 (8) ◽  
pp. 610-611 ◽  
Author(s):  
Jae‐Hyoung Cho ◽  
Se‐Yun Kim
Keyword(s):  
Radiation Pattern ◽  
Near Field ◽  
Dipole Antenna ◽  
Field Radiation

scholarly journals A Generalized Approach for Computation of Near Field Radiation Pattern of an Antenna

2014 ◽  
Vol 2014 ◽  
pp. 1-18
Author(s):  
Preetham Shankpal ◽  
Varun Arur ◽  
Govind Kadambi ◽  
James Shuttleworth
Keyword(s):  
Radiation Pattern ◽  
Near Field ◽  
Circular Waveguide ◽  
Field Analysis ◽  
Far Field ◽  
Magnetic Dipoles ◽  
Underlying Principle ◽  
Field Radiation ◽  
Conical Horn

A generalized procedure in the form of an analytical formulation for the determination of radiation pattern of an antenna at any arbitrary distance which covers the near field as well as far field is presented in this paper. With the prior knowledge of either the current or field distribution on the radiating aperture, the proposed near field analysis is generic and can be applied for wide variety of antenna elements. The underlying principle of the generalized procedure is tantamount to considering the radiating aperture as an array of point electric and magnetic dipoles. The validity and novelty of the proposed new approach have been substantiated considering an open ended circular cylindrical waveguide and a conical horn as case studies and treating the far field as a special case of near field with pertinent distance criterion. The effect of change in the distance of observation ranging from reactive near field to far field on the radiation patterns of these antennas has also been discussed. The simulation studies reveal that the depicted normalized phase patterns of both the circular waveguide and conical horn follow the changes in the profile of the corresponding amplitude patterns.

scholarly journals Planar Array Failed Element(s) Radiation Pattern Correction: A Comparison

2021 ◽  
Vol 11 (19) ◽  
pp. 9234
Author(s):  
Navaamsini Boopalan ◽  
Agileswari K. Ramasamy ◽  
Farrukh Nagi ◽  
Ammar Ahmed Alkahtani
Keyword(s):  
Radiation Pattern ◽  
Phased Arrays ◽  
Signal To Noise Ratio ◽  
Near Field ◽  
Optimization Methods ◽  
Pattern Search ◽  
Reference Pattern ◽  
Optimal Weights ◽  
Planar Array ◽  
Field Radiation

Phased arrays are widely used in different fields, such as broadcasting, radar, optics, and space communications. The principle of phased arrays is to generate a directed signal from a large number of antennas to be steered at any desired angle. This, however, increases the probability of defective elements in an array. Faulty elements in an array cause asymmetry and result in increased sidelobe levels which rigorously distort the radiation pattern. Increased sidelobe radiation wastes energy and can cause interference by radiating and receiving signals in unintended directions. Therefore, it is necessary to find a method that can provide accuracy in the radiation pattern transmitted or received in the presence of failed element(s) in an array. This paper compares the few available optimization methods, namely, simulated annealing (SA), Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Pattern Search (PS) methods. For each method, various types of failures were examined, and the most suitable techniques to recover the far-field radiation are recommended. The optimization is then carried out by selecting the optimal weights of the remaining working elements in the planar array. The optimized radiation pattern’s efficiency was evaluated by comparing the Signal to Noise Ratio (SNR) value of the optimized radiation with reference and failed radiation patterns. The PSO method showed a better performance compared to all the other methods in reducing the failed radiation pattern’s SNR value. In various types of failure tests, this method reduced the failed radiation pattern’s SNR from 1 to 10 dB. This method also successfully produced a radiation pattern that closely matches the reference pattern before any failed element(s) are presented in the array. The life cycle of a planar array system with faulty elements can be increased by optimizing the remaining active elements in the array with the PSO method. It also reduces the cost of restoring and replacing the failed elements in an array regularly. This approach also prevents near-field measurement that requires complicated processes using costly equipment.

Near field radiation pattern of tapered monomode optical waveguides

1982 ◽  
Vol 41 (2) ◽  
pp. 95-98 ◽  
Author(s):  
Paolo Bassi ◽  
De Yu Zang ◽  
Daniel B. Ostrowsky
Keyword(s):  
Radiation Pattern ◽  
Optical Waveguides ◽  
Near Field ◽  
Field Radiation

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.

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