Results 271 to 280 of about 2,275,236 (300)

Optimization of Radiating Fields and the Example of Null-Placement

2000
In this contribution, we describe a systematic approach to a class of optimization problems for electromagnetic radiation which are of some practical interest for the design of effective telecommunication systems. We show that a general framework, developed in collaboration with R.E.
Angell, Thomas S., Kirsch, Andreas
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Pure radiation fields admitting nontrivial null symmetries

Journal of Mathematical Physics, 1984
The sixteen types of geometrical symmetries corresponding to the continuous groups of collineations and motions generated by a null vector n are considered. The common propagation vector of a pure electromagnetic radiation field and a pure gravitational radiation field is chosen to be n.
L. Radhakrishna, N.Ibohal Singh
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Vanishing radiation amplitudes: Physical null zones

Physical Review D, 1983
We examine and parametrize a region of the phase space for relativistic n-particle collisions in which radiation tree amplitudes vanish. The physical-null-zone theorem, which gives conditions for this null radiation zone to intersect the physical region, is proven.
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Null geodesics in the gravitational field of a rotating, radiating body

Journal of Mathematical Physics, 1993
A solution of the Einstein field equations for a rotating radiating body was presented by Carmeli and Kaye in 1977 [Ann. Phys. 103, 97 (1977)]. Their paper presented a new line element along with the corresponding energy-momentum tensor for the radiation field. The Newman–Penrose formalism [J. Math. Phys.
Hadley, R. H., Mallett, R. L.
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Null Electromagnetic Field in the Form of Spherical Radiation

Journal of Mathematical Physics, 1967
An example is given of a differential from which leads, through Einstein's gravitational equations, to an energy tensor representing a null electromagnetic field in the form of spherical radiation.
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Generation of Radiation Null for Periodic Leaky-Wave Antennas

2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT), 2019
In this paper a method for generating null region in the radiation pattern of periodic leaky-wave antennas is proposed. The method is based on the concept of effective radiation sections. The effective radiation section of the radiating mode (the $\mathrm{n}=-1$ harmonic) is calculated and studied. Then by suppressing the effective radiation sections
Zheng Li, Jianlai Wang, Xin Lv, Dawei Li, Junhong Wang   +4 more
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Gravitational radiation field of an isolated system at null infinity

Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences, 1990
Abstract The quadrupole and octupole contributions to the gravitational radiation flux at null infinity from an initially stationary isolated system are computed in terms of the asymptotic moments defined there. The present treatment incorporates the influence of the background field of the source while still neglecting the nonlinear ...
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Acoustic scattering and radiation problems, and the null-field method

Wave Motion, 1982
Abstract The best known methods for solving the scattering and radiation problems of acoustics are integral-equation methods. However, it is also known that the simplest of these methods yield equations which are not uniquely solvable at certain discrete sets of frequencies (the irregular frequencies).
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A Microstrip Filtering Antenna With Controllable Radiation Nulls

2023 IEEE 11th Asia-Pacific Conference on Antennas and Propagation (APCAP), 2023
Junyi Lv, Yulu Hu, Xu Cheng, Zhanhe Zhang, Luanfeng Gao, Xing Li, Bin Li   +6 more
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Broadband Omnidirectional Filtenna With Controllable Radiation Nulls and Bandwidth

Microwave and Optical Technology Letters
ABSTRACT A broadband omnidirectional filtering dipole antenna having controllable operating bandwidth and radiation nulls is proposed. A step‐shaped dipole antenna, driven by a 50 Ω coaxial cable, generates a basic resonant mode for omnidirectional radiation.
Li Neng Huang, Ming Yang Deng, Jian Ze Liu, Liang Hua Ye, Fan Jiang   +4 more
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