Slotted ridged waveguide antennas with partial dielectric filling

Antennas ◽  
2021 ◽  
Author(s):  
A. O. Pelevin ◽  
G. F. Zargano
Keyword(s):  
Dielectric Layer ◽  
Dielectric Material ◽  
Low Frequency ◽  
Ridge Waveguide ◽  
Mass Dimension ◽  
Slotted Waveguide ◽  
Ridged Waveguide ◽  
Dielectric Filling ◽  
Thin Dielectric Layer ◽  
Lower Frequencies

Slotted single-ridge waveguide antenna with dielectric filling has been simulated. Dielectric material has been used to fill the slots, and to form a thin layer directly under the slotted broad wall. The specific pairs of ridge dimensions have been found that provide the same cut-off frequency for an air-filled ridged waveguide as it is for a broader air-filled rectangular waveguide. It has been shown that waveguide ridging followed by insertion of a thin dielectric layer under the slotted wall shift consecutively the antenna operating band down to lower frequencies. The specific values of thickness and permittivity of the dielectric layer suitable for frequency shifting have been found. The simulated characteristics of a 20-element dielectrically filled slotted single-ridge waveguide antenna have been presented. Resultantly, the efficient method of shifting the operating interval of a slotted-waveguide antenna down to lower frequencies has been proposed. The method does not require a broader waveguide, and therefore is effective with respect to low frequency – mass/dimension trade-off.

STUDY OF PHASED ARRAYS OF SLOTTED WAVEGUIDE ANTENNAS WITH DIELECTRIC FILLING

2021 ◽  
pp. 42-47
Author(s):  
A. O. Pelevin ◽  
A. M. Lerer ◽  
G. F. Zargano
Keyword(s):  
Computer Simulation ◽  
Antenna Arrays ◽  
Dielectric Layer ◽  
Phased Arrays ◽  
Frequency Range ◽  
Phased Antenna Arrays ◽  
Operating Frequency Range ◽  
Slotted Waveguide ◽  
Dielectric Filling ◽  
Thin Dielectric Layer

The article describes the computer simulation of phased antenna arrays consisting of slotted waveguide antennas with air and dielectric filling. It is shown that inser-tion of a thin dielectric layer shifts the operating frequency range of phased anten-na arrays by 1 GHz or more down in frequency while maintaining directional char-acteristics.

Planar slotted ridged waveguide antenna arrays with dielectric layer

2021 ◽  
Author(s):  
A.O. Pelevin ◽  
G.F. Zargano ◽  
A.M. Lerer
Keyword(s):  
Dielectric Layer ◽  
Ridge Waveguide ◽  
Main Beam ◽  
Operating Range ◽  
Planar Arrays ◽  
Ridge Waveguides ◽  
Linear Elements ◽  
Slotted Waveguide ◽  
Phase Scan ◽  
Dielectric Filling

The paper simulates the options available to move operating range of slotted waveguide antennas downward in frequency without changing the waveguide cross-section, and suggests the ways for designing linear waveguide-slotted elements based on rectangular and ridge waveguides with air and partial dielectric filling. The critical frequency of the fundamental mode of a 16x8 mm rectangular waveguide moves by ridging from 9.5 to 6.5 GHz. Partial dielectric filling of the cavity of the ridge waveguide makes it possible to additionally shift the operating range downward in frequency by 6-10% without making changes to antenna design. The antenna characteristics of linear arrays based on a dielectric-filled ridge slotted waveguide have been compared in terms of gain and voltage standing wave ratio to similar designs of arrays on rectangular and air-filled analogues. Based on the obtained structures of linear elements, simulation models of planar arrays have been constructed so that they have the similar area of total surface. Simulated frequency dependence of the realized gain for planar arrays has demonstrated a shift of the operating range downward in frequency. The analysis of the directivity characteristics of planar arrays for various phase shifts between the linear elements has been carried out. The simulation results have shown that the use of a dielectric-filled ridge waveguide gives an advantage in phase scan angle of the main beam of the radiation pattern. With the same phase shift, in planar arrays of dielectric-filled ridge waveguides, the main beam scans for a larger angle while keeping side lobes at low level. Thus, the use of a ridge slotted waveguide with a dielectric layer inside makes it possible to expand the phase scan angle.

Three Dimensional Bacteria Concentration by Negative Dielectrophoresis

2013 ◽  
Vol 699 ◽  
pp. 251-256
Author(s):  
T. Hisajima ◽  
L. Mao ◽  
K. Shinzato ◽  
M. Nakano ◽  
J. Suehiro
Keyword(s):  
Escherichia Coli ◽  
Numerical Simulation ◽  
Dielectric Layer ◽  
Parallel Plate ◽  
Three Dimensional ◽  
Three Dimension ◽  
Escherichia Coli Cells ◽  
Opposite Electrode ◽  
Novel Method ◽  
Thin Dielectric Layer

Thispaper reports a novel method to concentrate bacteria in three-dimension by negative dielectrophoretic (n-DEP) force in a microchannel. This was achieved by placing a thin dielectric layer on one of a pair of parallel plate electrodes. The dielectric layer having a home-plate like pentagonal shape, forms a gradient of electric field causing n-DEP. A three-dimensional numerical simulation of bacteria trajectory predicts that bacteria flowing a microchannel were three-dimensionally concentrated beneath the tip of the pentagonal dielectric thin layer. The trajectory and concentration of bacteria under n-DEP force were also experimentally confirmed using Escherichia coli cells. Bacteria moved along edges of the dielectric layer and were pushed to the opposite electrode, resulting in their concentration in three-dimension. The proposed device might be applicable to selective concentration of bacteria depending on their dielectric properties.

scholarly journals Detection of infrasound by the Atlantic cod

1986 ◽  
Vol 125 (1) ◽  
pp. 197-204 ◽  
Author(s):  
O. Sand ◽  
H. E. Karlsen
Keyword(s):  
Ambient Noise ◽  
Atlantic Cod ◽  
Low Frequency ◽  
Directional Pattern ◽  
Frequency Noise ◽  
Threshold Values ◽  
Sensory Inputs ◽  
A Value ◽  
Cardiac Conditioning ◽  
Lower Frequencies

Below about 50 kHz the level of ambient noise in the sea increases continuously towards lower frequencies. In the infrasound range the spectral slope is particularly steep. This low-frequency noise may propagate long distances with little attenuation, causing a directional pattern of infrasound in the sea. Using a standing-wave acoustic tube, we have studied the sensitivity of cod to infrasound down to 0.1 Hz by means of the cardiac conditioning technique. The threshold values, measured as particle acceleration, showed a steady decline towards lower frequencies below 10 Hz, reaching a value close to 10(−5)ms-2 at 0.1 Hz. The spectrum level at 0.1 Hz in the sea ranges between 120 and 180 dB (re 1 microPa), with corresponding particle accelerations from less than 10(−6) to more than 10(−4)ms-2. The sensitivity of cod is thus sufficient to detect the highest levels of ambient infrasound, and we put forward the hypothesis that fish may utilize information about the infrasound pattern in the sea for orientation during migration, probably in addition to an array of other sensory inputs.

scholarly journals Understanding Dielectrics: Impact of External Salt Water Bath

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2033
Author(s):  
Jonathan Phillips ◽  
Alexander Roman
Keyword(s):  
Energy Density ◽  
Power Density ◽  
Parallel Plate ◽  
Dielectric Material ◽  
Salt Water ◽  
Low Frequency ◽  
Ambient Air ◽  
Dielectric Materials ◽  
Standard Theory ◽  
Parallel Plate Capacitor

As predicted by the theory of super dielectric materials, simple tests demonstrate that dielectric material on the outside of a parallel plate capacitor dramatically increases capacitance, energy density, and power density. Simple parallel plate capacitors with only ambient air between the plates behaved as per standard theory. Once the same capacitor was partially submerged in deionized water (DI), or DI with low dissolved NaCl concentrations, still with only ambient air between the electrodes, the capacitance, energy density, and power density, at low frequency, increased by more than seven orders of magnitude. Notably, conventional theory precludes the possibility that material outside the volume between the plates will in any fashion impact capacitive behavior.

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