scholarly journals Generation of Circularly Polarized Quasi-Non-Diffractive Vortex Wave via a Microwave Holographic Metasurface Integrated with a Monopole

2021 ◽  
Vol 11 (15) ◽  
pp. 7128
Author(s):  
Chen Zhang ◽  
Li Deng ◽  
Ling Wang ◽  
Xue Chen ◽  
Shufang Li
Keyword(s):  
Secure Communication ◽  
High Capacity ◽  
Diffraction Theory ◽  
Circularly Polarized ◽  
Impedance Modulation ◽  
Left Handed ◽  
Intelligent Detection ◽  
Resolution Imaging ◽  
Novel Method ◽  
External Feeding

In this paper, a novel method for generating a circularly polarized (CP) quasi-non-diffractive vortex wave carrying orbital angular momentum (OAM), based on the microwave holographic metasurface integrated with a monopole, is proposed. This method is the combination of the non-diffraction theory and the principle of waveguide-fed-based holography and is equivalent to a superposition of two scalar impedance modulation surfaces. To verify the proposed method, a holographic metasurface generating a left-handed circularly polarized (LHCP) quasi-non-diffractive vortex wave carrying −1 mode OAM at the normal direction, was simulated and analyzed. The metasurface consisted of inhomogeneous slot units on a grounded substrate and a monopole excitation. Moreover, the location distribution of slots was determined by a computed interferogram between the reference wave and the object wave with the non-diffractive feature. Compared with an ordinary vortex wave, the quasi-non-diffractive wave obtained by our proposed method possessed a smaller divergence radius and a stronger electric field strength in the 9 times wavelength range. It paved a new path for manipulating the non-diffractive vortex wave in medium distance without using an external feeding source, which holds great potential for the miniaturization devices applied in medium-distance high-capacity secure communication, high-resolution imaging and intelligent detection.

Modulation instability in nonlinear chiral fiber

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Demissie Jobir Gelmecha ◽  
Ram Sewak Singh
Keyword(s):  
Theoretical Model ◽  
Numerical Simulations ◽  
Pulse Propagation ◽  
Modulation Instability ◽  
Constitutive Relations ◽  
Gain Spectrum ◽  
Circularly Polarized ◽  
Left Handed ◽  
Simulation Results ◽  
The Difference

AbstractIn this paper, the rigorous derivations of generalized coupled chiral nonlinear Schrödinger equations (CCNLSEs) and their modulation instability analysis have been explored theoretically and computationally. With the consideration of Maxwell’s equations and Post’s constitutive relations, a generalized CCNLSE has been derived, which describes the evolution of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) components propagating through single-core nonlinear chiral fiber. The analysis of modulation instability in nonlinear chiral fiber has been investigated starting from CCNLSEs. Based on a theoretical model and numerical simulations, the difference on the modulation instability gain spectrum in LCP and RCP components through chiral fiber has been analyzed by considering loss and chirality into account. The obtained simulation results have shown that the loss distorts the sidebands of the modulation instability gain spectrum, while chirality modulates the gain for LCP and RCP components in a different manner. This suggests that adjusting chirality strength may control the loss, and nonlinearity simultaneously provides stable modulated pulse propagation.

scholarly journals A high-efficiency and ultrathin transmission-type circular polarization converter based on surface structure

2021 ◽  
Vol 8 ◽  
pp. 4
Author(s):  
Peng Xu ◽  
Wei Xiang Jiang ◽  
Xiao Cai ◽  
Yue Gou ◽  
Tie Jun Cui
Keyword(s):  
High Efficiency ◽  
Transmission Mode ◽  
Polarization Converter ◽  
Periodic Surface ◽  
Circularly Polarized ◽  
Left Handed ◽  
Via Holes ◽  
Working Frequency ◽  
The Right ◽  
Good Agreement

In this paper, we propose, design and fabricate a kind of ultrathin and high-efficiency circularly polarization converter based on artificially engineered surfaces in the transmission mode. The converter is composed of double-layer periodic surface structures with cross slots. The top and bottom layers are printed on both sides of the F4B substrate and connected by metallic via holes. The proposed converter can transform the right-handed circularly polarized incident electromagnetic (EM) wave to a left-handed circularly-polarized one with near-unity efficiency in the transmission mode, or vice versa. We explain the conversion mechanism based on numerical simulations and equivalent circuit (EC) theory. The measured result has a good agreement with the simulated one in the working frequency band. Such ultrathin polarization converters can be used in wireless microwave communication, remote sensing, and EM imaging where circularly polarization diversity is needed.

scholarly journals Dual-Circularly Polarized 60 GHz Beam-Steerable Antenna Array with 8 × 8 Butler Matrix

2020 ◽  
Vol 10 (7) ◽  
pp. 2413 ◽  
Author(s):  
Yuntae Park ◽  
Jihoon Bang ◽  
Jaehoon Choi
Keyword(s):  
Circular Polarization ◽  
Antenna Array ◽  
Mutual Coupling ◽  
Beam Steering ◽  
60 Ghz ◽  
Circularly Polarized ◽  
Butler Matrix ◽  
Left Handed ◽  
Steerable Antenna ◽  
The Right

A beam-steerable dual-circularly polarized 60 GHz antenna array is proposed. A 1 × 4 dual-fed stacked patch antenna array is integrated with an 8 × 8 Butler matrix. By utilizing the 8 × 8 Butler matrix, the proposed antenna array generates dual-circular polarization with beam-steering capability. The proposed antenna array system demonstrates good reflection coefficients in the frequency band ranging from 55.3 GHz to 64.9 GHz and has a mutual coupling of less than −10 dB over the frequency range of 57.5 GHz–63.2 GHz. At 60 GHz, the maximum gains and beam-steering angles for input ports 2, 4, 5, and 7 are 9.39 dBi at −38°, 10.67 dBi at −11°, 10.63 dBi at +11°, and 9.38 dBi at +39°, respectively. It is also demonstrated that the dual-polarization is well formed by switching the excitation ports. The right-handed circular polarization (RHCP) is formed when four ports from port 1 to port 4 are excited and left-handed circular polarization (LHCP) is formed when four ports from port 5 to port 8 are excited. The proposed antenna array system could be a good candidate for millimeter-wave 5G applications that require wide beam coverage and polarization diversity.

scholarly journals Intelligent Detection of Black Hole Attacks for Secure Communication in Autonomous and Connected Vehicles

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 199618-199628
Author(s):  
Zohaib Hassan ◽  
Amjad Mehmood ◽  
Carsten Maple ◽  
Muhammad Altaf Khan ◽  
Abdulaziz Aldegheishem
Keyword(s):  
Black Hole ◽  
Secure Communication ◽  
Connected Vehicles ◽  
Intelligent Detection

scholarly journals Balanced gain for a square metaloop antenna

2019 ◽  
Vol 6 ◽  
pp. 3
Author(s):  
Hisamatsu Nakano ◽  
Ittoku Yoshino ◽  
Tomoki Abe ◽  
Junji Yamauchi
Keyword(s):  
Frequency Response ◽  
Radiation Pattern ◽  
Free Space ◽  
Loop Antenna ◽  
Circularly Polarized ◽  
Left Handed ◽  
The Difference

A square loop antenna implemented using a metamaterial line, referred to as a metaloop, is discussed. The metaloop radiates a counter circularly polarized (CP) broadside beam when the loop circumference equals one guided wavelength. The frequency response of the gain shows two different maximum values: gain G Lmax for a left-handed CP wave at frequency fGLmax and gain GRmax for a right-handed CP wave at frequency fGRmax, where GLmax is smaller than GRmax. In order to increase GLmax, while not affecting the original GRmax as much as possible (i.e. balance the gain), a parasitic natural conducting loop (paraloop), whose circumference is one free-space wavelength at fGLmax, is placed at height Hpara above the metaloop. It is found that the difference in the gains can be reduced by choosing an appropriate Hpara. The radiation pattern at fGLmax is narrowed by the paraloop, while the VSWR is not remarkably affected.

Circularly polarized microstrip antenna arrays with reduced mutual coupling using metamaterial

2015 ◽  
Vol 8 (8) ◽  
pp. 1253-1263 ◽  
Author(s):  
R. Hafezifard ◽  
Jalil Rashed-Mohassel ◽  
Mohammad Naser-Moghadasi ◽  
R. A. Sadeghzadeh
Keyword(s):  
Antenna Arrays ◽  
Microstrip Antenna ◽  
Mutual Coupling ◽  
Ground Plane ◽  
High Gain ◽  
Ring Resonators ◽  
Magnetic Characteristics ◽  
Circularly Polarized ◽  
Antenna Performance ◽  
Left Handed

A circularly polarized (CP) and high gain Microstrip antenna is designed in this paper using metamaterial concepts. The antenna, built on a metamaterial substrate, showed significant size reduction and less mutual coupling in an array compared with similar arrays on conventional substrates. Demonstrated to have left-handed magnetic characteristics, the methodology uses complementary split-ring resonators (SRRs) placed horizontally between the patch and the ground plane. In order to reduce mutual coupling in the array structure, hexagonal-SRRs are embedded between antenna elements. The procedure is shown to have great impact on the antenna performance specifically its bandwidth which is broadened from 400 MHz to 1.2 GHz for X-band and as well as its efficiency. The structure has also low loss and improved standing wave ratio and less mutual coupling. The results show that a reduction of 26.6 dB in mutual coupling is obtained between elements at the operation frequency of the array. Experimental data show a reasonably good agreement between simulation and measured results.

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