Radiation Pattern Reconfigurable Waveguide Slot Array Antenna Using Liquid Crystal

In this paper, we proposed a radiation pattern reconfigurable waveguide slot array antenna using liquid crystal (LC). Together with the waveguide slot, the designed complementary electric-field-coupled resonator functions like a switch controlled by the dielectric constant of the LC, which can control the antenna element to radiate or not. Thus, the array factor and radiation pattern can be manipulated. The proposed antenna was simulated, fabricated, and measured. Its radiation direction can be reconfigured to 46° or 0° at about 15 GHz.

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Influence of Electric Field Distribution on High-Power Array Antenna Radiation Pattern with Rectangular Aperture

Chinese Physics Letters ◽

10.1088/0256-307x/31/6/068401 ◽

2014 ◽

Vol 31 (6) ◽

pp. 068401

Author(s):

Yi-Ming Yang ◽

Cheng-Wei Yuan ◽

Bao-Liang Qian

Keyword(s):

Electric Field ◽

Radiation Pattern ◽

Field Distribution ◽

High Power ◽

Electric Field Distribution ◽

Array Antenna ◽

Antenna Radiation ◽

Antenna Radiation Pattern ◽

Rectangular Aperture

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Wideband and High-Gain Corporate-Fed Gap Waveguide Slot Array Antenna With ETSI Class II Radiation Pattern in $V$ -Band

IEEE Transactions on Antennas and Propagation ◽

10.1109/tap.2016.2634282 ◽

2017 ◽

Vol 65 (4) ◽

pp. 1823-1831 ◽

Cited By ~ 34

Author(s):

Abbas Vosoogh ◽

Per-Simon Kildal ◽

Vessen Vassilev

Keyword(s):

Radiation Pattern ◽

Class Ii ◽

High Gain ◽

Array Antenna ◽

Waveguide Slot ◽

V Band

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MOLECULAR MECHANISMS OF HIGHLY POLAR LIQUID CRYSTAL DIELECTRIC POLARIZATION

Tyumen State University Herald Physical and Mathematical Modeling Oil Gas Energy ◽

10.21684/2411-7978-2021-7-1-44-59 ◽

2021 ◽

Vol 7 (1) ◽

pp. 44-59

Author(s):

Umardjon M. Mallaboev ◽

Victor I. Novoselov ◽

Olga S. Zaitseva

Keyword(s):

Dielectric Constant ◽

Liquid Crystal ◽

Electric Field ◽

Molecular Mechanisms ◽

Relaxation Times ◽

Dielectric Constants ◽

Polar Liquid ◽

Isotropic Phase ◽

Relaxation Processes ◽

Dielectric Polarization

This article studies the dielectric constants of the nematic ε, ε, and isotropic εis phases of a highly polar liquid crystal of 4-cyanophenyl ether of 4′-n-octyloxybenzoic acid in the megahertz range of electric field frequencies (105-108) Hz, as well as the anisotropy of the dielectric constant Δε = ε − ε. The authors have revealed the relaxation processes and mechanisms responsible for them. In addition, they calculated the relaxation times, dipole polarization activation energy, and deceleration parameters in the nematic phase. The design of a measuring cell is presented, which allows studying the dielectric constant of the liquid crystal at various orientations of the director (provided by the magnetic field) relative to an alternating electric field with small volumes of matter. The results show that the dispersion of the dielectric constant in the investigated frequency range of the electric field is characterized by two relaxation processes with τ ~3 ∙ 10−8 s and (τ)в ~ 1,5 ∙ 10−9 s. The dispersion mechanisms are due to the rotation of polar molecules about their short and long axes respectively. The dispersion of the dielectric constant corresponds to the spectrum of relaxation times. The dispersion mechanisms are associated with two relaxation processes: the precession of molecules along a cone within the spatial angle allowed by the value of the order parameter of the liquid crystal S < 1, and the rotation of molecules around the longitudinal axes. The relaxation times corresponding to these mechanisms are commensurate with each other. The dispersion of the dielectric constant in the isotropic phase is characterized by a relaxation process with τis ~ 6 ∙ 10−9 s. The dispersion mechanism is due to the rotation of molecules around short axes.

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Novel Design of High-Gain Planar Dipole-Array Antenna for RFID 2.45 GHz

International Journal of Antennas and Propagation ◽

10.1155/2014/704974 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

Danpeng Xie ◽

Xueguan Liu ◽

Huiping Guo ◽

Xinmi Yang

Keyword(s):

Radiation Pattern ◽

High Gain ◽

Base Station ◽

Array Antenna ◽

Phase Retardation ◽

Parallel Lines ◽

Novel Design ◽

Radiation Direction ◽

Peak Gain

This paper presents a novel high-gain planar dipole-array antenna for 2.45 GHz which consists of four planar dipole elements placed in two parallel lines. Phase retardation of each element is set by feeding network to form controllable radiation direction. The radiation pattern of the array is discussed according to Arrays Theorem. The measured −10 dB band is from 2.3 GHz to 2.57 GHz, and peak gain in this band is 7.5 dBi. The gain can even reach 10.5 dBi after installing additional ground. The proposed antenna has advantages of high gain, controllable direction, and planarity which are suitable for 2.45 GHz RFID base station.

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