Study of OAM mode purity by changing the orientation of antenna element
18 May 2018-pp 180-183
TL;DR: An investigation of 8 elements uniform circular array (UCA) for different Orbital Angular Momentum (OAM) modes is carried out for three designs and the effect of array radius on OAM purity and the radial outward design to reduce phase complexity is discussed.
Abstract: Orbital angular momentum concept has discussed with the help of mathematical equations. An investigation of 8 elements uniform circular array (UCA) for different Orbital Angular Momentum (OAM) modes is carried out for three designs. The effect of array radius on OAM purity and the radial outward design to reduce phase complexity is discussed. Uniform circular antenna array for all possible combination has been simulated and its results are demonstrated for different physical and electrical characteristic.
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TL;DR: This work demonstrates a 32-Gbit’s−1 millimetre-wave link over 2.5 metres with a spectral efficiency of ~16 bit s− 1 Hz−1 using four independent orbital–angular momentum beams on each of two polarizations, and shows an 8-Gbits−1 link containing two orbital angular momentum beams with crosstalk less than −12.5 dB.
Abstract: One property of electromagnetic waves that has been recently explored is the ability to multiplex multiple beams, such that each beam has a unique helical phase front. The amount of phase front ‘twisting’ indicates the orbital angular momentum state number, and beams with different orbital angular momentum are orthogonal. Such orbital angular momentum based multiplexing can potentially increase the system capacity and spectral efficiency of millimetre-wave wireless communication links with a single aperture pair by transmitting multiple coaxial data streams. Here we demonstrate a 32-Gbit s−1 millimetre-wave link over 2.5 metres with a spectral efficiency of ~16 bit s−1 Hz−1 using four independent orbital–angular momentum beams on each of two polarizations. All eight orbital angular momentum channels are recovered with bit-error rates below 3.8 × 10−3. In addition, we demonstrate a millimetre-wave orbital angular momentum mode demultiplexer to demultiplex four orbital angular momentum channels with crosstalk less than −12.5 dB and show an 8-Gbit s−1 link containing two orbital angular momentum beams on each of two polarizations. High speed data transmission using orbital angular momentum beams has been recently demonstrated. Here, Yan et al. demonstrate a 32 Gbit/s millimetre-wave communication link using eight coaxially propagating independent orbital angular momentum beams with four orbital angular momentum states on two orthogonal polarizations.
1,002 citations
"Study of OAM mode purity by changin..." refers methods in this paper
...By using OAM concept in radio waves, we can increase the channel capacity [1-3]....
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TL;DR: It is shown numerically that vector antenna arrays can generate radio beams that exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics.
Abstract: We show numerically that vector antenna arrays can generate radio beams that exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (1 GHz), digital techniques can be used to coherently measure the instantaneous, local field vectors and to manipulate them in software. This enables new types of experiments that go beyond what is possible in optics. It allows information-rich radio astronomy and paves the way for novel wireless communication concepts.
903 citations
TL;DR: In this paper, it was shown experimentally that two beams of incoherent radio waves, transmitted on the same frequency but encoded in two different orbital angular momentum states, can simultaneously transmit two independent radio channels.
Abstract: We have shown experimentally, in a real-world setting, that it is possible to use two beams of incoherent radio waves, transmitted on the same frequency but encoded in two different orbital angular momentum states, to simultaneously transmit two independent radio channels. This novel radio technique allows the implementation of, in principle, an infinite number of channels in a given, fixed bandwidth, even without using polarization, multiport or dense coding techniques. This paves the way for innovative techniques in radio science and entirely new paradigms in radio communication protocols that might offer a solution to the problem of radio-band congestion.
899 citations
"Study of OAM mode purity by changin..." refers methods in this paper
...By using OAM concept in radio waves, we can increase the channel capacity [1-3]....
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TL;DR: In this paper, the authors used vector field-sensing electric and magnetic triaxial antennas to estimate the orbital angular momentum (OAM) of radio beams, assuming ideal (noiseless) conditions and that the beam axis is known.
Abstract: Recent discoveries concerning rotating (helical) phase fronts and orbital angular momentum (OAM) of laser beams are applied to radio frequencies and comprehensive simulations of a radio OAM system are performed. We find that with the use of vector field-sensing electric and magnetic triaxial antennas, it is possible to unambiguously estimate the OAM in radio beams by local measurements at a single point, assuming ideal (noiseless) conditions and that the beam axis is known. Furthermore, we show that conventional antenna pattern optimization methods can be applied to OAM-generating circular arrays to enhance their directivity.
700 citations
"Study of OAM mode purity by changin..." refers background in this paper
...N/2 lmax N/2 [7]....
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...The largest OAM mode number (lmax) by N element antenna array is -N/2 < lmax < N/2 [7]....
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...The highest purity may be possible for OAM mode l < N/2. i.e. l = 3 for 8 element array....
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TL;DR: In this paper, a radial uniform circular array (UCA) is proposed for orbital angular momentum (OAM) generation and dual-mode communication based on a multilayer design, which achieves good −15-dB bandwidths at the ±1 modes, and a very weak cross coupling (less than −24 dB) exists in this frequency band.
Abstract: A radial uniform circular array (UCA) is proposed for orbital angular momentum (OAM) generation and dual-mode communication based on a multilayer design. Theoretical derivation is presented for the demonstration of the OAM generation from radial UCAs. The UCA of single mode is realized by cascading an eight-dividing feeding network with equal magnitude and specific phases for each of two neighbor ports and eight microstrip antenna elements. Both the full-wave simulations and measurements of a final fabricated antenna array are carried out. From 5.72 to 5.95 GHz, the proposed antenna possesses good −15-dB bandwidths at the ±1 modes, and a very weak cross coupling (less than −24 dB) exists in this frequency band. The helical phase wavefronts are obtained, and the radiation patterns are presented. Moreover, the dual-mode multiplexing is achieved with isolations of different channels more than 19 dB in measurements.
101 citations
"Study of OAM mode purity by changin..." refers methods in this paper
...Phased Uniform Circular Array (UCA) is a simplest way to produce ±lth order OAM mode with N antenna element [4-6], which is comparatively small, Low profile, planner and easy to fabricate....
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