scholarly journals AN ANTENNA BASED ON A HYBRID METAL–DIELECTRIC STRUCTURE

2021 ◽  
Vol 26 (3) ◽  
pp. 270-277
Author(s):  
D. V. Mayboroda ◽  
◽  
S. O. Pogarsky ◽  
Keyword(s):  
Standing Wave ◽  
Dielectric Waveguide ◽  
Periodic Sequence ◽  
Voltage Standing Wave Ratio ◽  
Dielectric Waveguides ◽  
Dielectric Structure ◽  
Frequency Range ◽  
Dielectric Plate ◽  
Frequency Selection ◽  
Near Zone

Purpose: Nowadays, in the millimeter frequency range, the dielectric waveguides of various modifications have certain advantages over the standard metal waveguides, primarily due to the possibility of creating functional units based on them. This is due to the relative simplicity and low cost of manufacturing the dielectric waveguides and functional units using them, the high degree of their integration with active elements, the use in their manufacture of different dielectrics and polymers with a wide range of material constants and a variety of mechanical properties (in particular, some materials have a significant flexibility). After making a series of physical experiments we have found the possibility of implementing the frequency selection and radiation into free space of electromagnetic waves by a hybrid metal-dielectric structure. Design/methodology/approach: The studied electrodynamic structure belongs to the class of hybrid metal-dielectric structures. It includes a modified inverted dielectric waveguide with a periodic sequence on the dielectric plate of fifteen dielectric rods with metallized coating on one of the faces placed outwards. The structure efficiency was estimated by the voltage standing-wave ratio (VSWR) values and power attenuation in the duct. The measurements were made with the reflectometer method. To estimate the degree of electromagnetic field concentration near the rod inhomogeneities in the near zone, the mobile probe method was used. The field structures were visualized with the method of isolines. Findings: The results of a series of experimental investigations showed the possibility of matching the structure with the external waveguides in the frequency range of 26.5-32.5 GHz with the voltage standing-wave ratio (VSWR) less than 1.8. The frequency dependence of attenuation is oscillatory with clearly expressed frequency ranges with small and large attenuation values. Moreover, the dependence is almost periodic, which is typical of periodic structures. The frequency response slope in the transition zones can be quite high and reach values of 41.26 dB/GHz. The degree of concentration of the electric field near the waveguide dielectric rod and the degree of excitation of the dielectric inhomogeneities was found by directly measured electric field strength in the near zone. Measurements of energy characteristics made under the short-circuit conditions for the main guide and in the mode of matched load of the main guide showed both the ability to control the polarization characteristics and the ability to change the appearance of the pattern and its orientation in space. Conclusions: It has been experimentally proven that a hybrid metal-dielectric structure, being a modified inverted dielectric waveguide with a periodic sequence on the dielectric plate of fifteen dielectric rods with metalized coating on one of the faces placed outwards, can be effectively integrated into a standard transmission line. It is found that this structure can be matched with the external circuits in a fairly wide frequency range. It is also found that in different frequency ranges this hybrid metal-dielectric structure shows the possibility of both efficient frequency selection and radiation in free space. Antenna measurements have shown the beam pattern shape controllability. Key words: inverted dielectric waveguide, periodic sequence, voltage standing-wave ratio (VSWR), attenuation, reflectometer method, mobile probe method, directivity pattern

scholarly journals Optimization of the method for exciting an inverted strip dielectric waveguide with metal plane

2019 ◽  
Keyword(s):  
Electromagnetic Field ◽  
Insertion Loss ◽  
Dielectric Waveguide ◽  
Wave Mode ◽  
Dielectric Constants ◽  
Dielectric Waveguides ◽  
Frequency Selection ◽  
Selection Mode ◽  
Functional Units ◽  
Dielectric Structures

Background. Currently, the application of various types of dielectric waveguides in the millimeter wavelength range is very promising, including metal-dielectric structures and functional units based on them. This is due to the simplicity and low cost of manufacturing dielectric waveguides and functional units based on them, the possibility of their integration with active elements, the use of various dielectrics and polymers having both a wide range of dielectric constants and a variety of mechanical properties (in particular, some dielectric materials have significant flexibility).Objectives. To optimize the method of excitation of one of its eigenwaves in a inverted strip dielectric waveguide with a metal plane through a series of physical experiments.Materials and methods. The studied electrodynamic structure belongs to the class of hybrid metal-dielectric structures. Its basis is a inverted strip dielectric waveguide with a metal plane. A feature of the used inverted strip dielectric waveguide is its composition: the main part of the waveguide rod adjacent to the metal plane is made of polystyrene, the second part is made of fluoroplastic. The evaluation of the excitation efficiency was carried out by the magnitude of the introduced attenuation into the tract. Using the method of a moving probe, the degree of concentration of the electromagnetic field near a complex compositional waveguiding rod was estimated. The fields were visualized using the contour method.Results. Based on a series of experimental studies, the method for exciting an inverted strip dielectric waveguide with a metal plane is optimized. The effect of optimal excitation was achieved through the use of the composite design of the dielectric waveguiding rod. With the optimal ratio of the material constants of the layers forming the waveguiding rod and the geometric parameters of these layers, it was possible to significantly expand the working frequency band, within which the level of insertion loss did not exceed the specified values. It was found that the electromagnetic field is concentrated mainly near the dielectric rod, providing a stable wave mode. It has been established that with a certain ratio of structure parameters, the frequency selection mode can be implemented in it. Conclusions. In the course of physical measurements, it was found that a inverted strip dielectric waveguide with a metal plane with the optimal choice of parameters is able to effectively maintain the wave mode with a low level of insertion loss. In general, a structure with a certain choice of parameters can operate in two regimes: waveguiding mode and frequency selection mode.

scholarly journals Radiating structure based on inverted dielectric waveguide with additional elements

2018 ◽  
Keyword(s):  
Dielectric Waveguide ◽  
Electromagnetic Compatibility ◽  
Short Circuit ◽  
Near Field ◽  
Travelling Wave ◽  
Wave Mode ◽  
Field Structure ◽  
Problem Solution ◽  
Dielectric Structure ◽  
Dielectric Plate

Background. Creation of effective radiating structures operating in millimeter range is one of the important directions in modern microwave technology. The use of different hybrid metal-dielectric structures for this range becomes increasingly significant because of possible occurrence of certain physical effects, which are impossible in standard dielectric waveguides and structures on their basis.Objectives. Experimentally investigate the main electrodynamic characteristics of a hybrid metal-dielectric structure, including the ways of excitation and matching with external circuits, energy characteristics.Materials and methods. Hybrid metal-dielectric structure is based on inverted dielectric waveguide, which contains metallized base, dielectric rod made of polystyrene and additional dielectric plate made of glass ceramics. Auxiliary radiating elements in the form of rods of finite length with metallized face are located at certain period on the additional dielectric plate. The near-field structure measurements are carried out through the moving probe method. The isoline method has been used for field structure visualization.Results. The construction of a hybrid radiating structure based on inverted dielectric waveguide with periodically located additional rectangular dielectric rods. The radiation patterns have been measured in H-plane in two modes: short-circuit mode and travelling wave mode. Based on near-field structure measurements, the behavior of the electromagnetic wave propagating in the waveguiding rod and the degree of excitation of the metallized parts of additional structure elements are obtained. The degree of excitation of a surface wave and the possibility of its radiation are obtained. Based on this data, shielding elements insertion possibility and electromagnetic compatibility problem solution can be estimated. Conclusions: The research has revealed possible effective radiation in travelling wave mode with acceptable direct loss, provided by proposed hybrid metal-dielectric structure. Moreover, the structure can provide an acceptable level of matching with external circuits. The possibility of radiated fields with specified characteristics formation in the short circuit and traveling wave modes is demonstrated.

scholarly journals Bi-Ellipse Microstripline Antenna Array Varians

2021 ◽  
Author(s):  
Putu Artawan
Keyword(s):  
Reflection Coefficient ◽  
Antenna Array ◽  
Standing Wave ◽  
Microstrip Antenna ◽  
Communication Systems ◽  
Return Loss ◽  
Voltage Standing Wave Ratio ◽  
Frequency Range ◽  
X Band ◽  
Working Frequency

The objectives of this research include obtaining and verifying the impedance formula of the designed bi-ellipse microstrip antenna and correlating the results obtained through simulation and experimentation. The research also aims to obtain the structure and dimensions that provide optimal characteristics of the designed bi-ellipse microstrip antenna and produce a prototype at S, C and X-Band frequencies. This research produced the structure and dimensions of a bi-ellipse microstrip antenna that provide optimal characteristics of antenna. The characteristics results of the antenna parameters in this research include a 8x2 array, with a bandwidth value of around 100.0 MHz obtained at a working frequency of 7.09GHz (7.04 GHz - 7.14 GHz), with a reflection coefficient value of 0.02, Voltage Standing Wave Ratio (VSWR) of 1.06, return loss of −30.00 dB and a gain of 7.30 dB. For the 8x4 array, a bandwidth value of approximately 210.0 MHz is obtained at a working frequency range of 2.85GHz, which ranges from 2.74GHz - 2.95GHz, with a reflection coefficient value of 0.04, Voltage Standing Wave Ratio (VSWR) of 1.09, return loss of −27.06 dB and a gain of 8.19 dB. The results presented above fulfill the indicators of good antenna characteristics parameters applicable to radar communication systems.

scholarly journals Broadband Metal-Dielectric Waveguide Path with Low Losses in the EHF Range

2021 ◽  
Vol 8 (3) ◽  
pp. 89-98
Author(s):  
V. V. Krutskikh ◽  
◽  
A. Yu. Sizyakova ◽  
M. S. Minkara ◽  
A. R. Ibrahim ◽  
...  
Keyword(s):  
Dielectric Waveguide ◽  
Unit Length ◽  
Circular Cross Section ◽  
Dielectric Waveguides ◽  
Structural Elements ◽  
Frequency Range ◽  
Metal Shield ◽  
Metal Waveguide ◽  
Materials Used ◽  
Dielectric Filling

. The present paper is devoted to the design of a new shielded metal-dielectric waveguide with low losses (less than 0.5 dB/m) and wide bandwidth for the 90–100 GHz frequency range. Various types of waveguide structures were analyzed, such as metal waveguides, oversized metal waveguides, dielectric waveguides, dielectric waveguides with a metal shield and various designs of the dielectric filling element. Estimates of loss per unit length in them are obtained. The design of a waveguide containing an oversized round metal screen and a dielectric element consisting of a plate and a rod, located in the center of symmetry of the device, is proposed. The task of creating a transition from the investigated waveguide to a standard rectangular metal waveguide is considered. It is a horn transition from a circular cross-section to a rectangular one with a length of more than 25 wavelengths with a dielectric structure continuing the dielectric element of the waveguide path. As a result of the work, the ratios of the dimensions of the structural elements of the waveguide path and the materials used were obtained that satisfy the required losses.

scholarly journals Обнаружение высокочастотных альфвеновских колебаний в омических разрядах сферического токамака Глобус-М2

2021 ◽  
Vol 47 (12) ◽  
pp. 17
Author(s):  
И.М. Балаченков ◽  
Ю.В. Петров ◽  
В.К. Гусев ◽  
Н.Н. Бахарев ◽  
В.И. Варфоломеев ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Standing Wave ◽  
High Frequency ◽  
Low Density ◽  
Frequency Range ◽  
High Frequency Oscillations ◽  
Model Predictions ◽  
Mode Excitation ◽  
Order Of Magnitude ◽  
Frequency Chirping

In Globus-M2 ohmic discharges with low density, by means of Mirnov coils array, magnetic field oscillations with frequencies in 1 MHz range were detected. Frequency range of these oscillations significantly exceed the range of TAE and RSAE frequencies, which were previously observed on Globus-M and Globus-M2 tokamaks, and their amplitude, contrary, turned out to be up to an order of magnitude lower. It was found that high frequency oscillations are interrelated with suprathermal electron fraction. At the same time the observed instability seems to have Alfvenic nature, since its frequency correlates well with Alfven frequency scaling. It was also found that magnetic perturbation always forms standing wave with predominantly low toroidal wavenumbers, including n = 0 structure, which makes gap (e.g. TAE) mode excitation impossible. Frequency chirping during single bursts with δω ~ √t is consistent with hole-clump model predictions.

Design of Antipodal Vivaldi Antenna Array

2013 ◽  
Vol 380-384 ◽  
pp. 3465-3468
Author(s):  
Hai Bo Tang ◽  
Xiao Zhong Shui
Keyword(s):  
Antenna Array ◽  
Standing Wave ◽  
Voltage Standing Wave Ratio ◽  
Radiation Characteristics ◽  
Vivaldi Antenna ◽  
Cross Structure ◽  
Structure Array

Firstly in this paper,an antipodal Vivaldi antenna is designed.The bandwidth is from 6GHz to 18GHz. The simulated results show good electric performance and the voltage standing wave ratio is less than 2 in the whole bandwidth.Secondly depending on this unit,this paper designs two kinds of arrays and estimates their radiation characteristics,respectively.The one array is a 1×8 array and the another array is a X-cross structure array with four elements.

THEORY AND DESIGN OF A COAXIAL SUPPORTING BEAD MADE OF COMPOSITE DIELECTRICS

1961 ◽  
Vol 39 (6) ◽  
pp. 926-934
Author(s):  
Gilbert H. Owyang
Keyword(s):  
Standing Wave ◽  
Frequency Ratio ◽  
Low Voltage ◽  
Coaxial Line ◽  
Wide Band ◽  
Voltage Standing Wave Ratio ◽  
Physical Parameters ◽  
Minimum Frequency ◽  
Typical Design

The effect due to the presence of a single supporting bead made of composite dielectrics in a coaxial line is being studied. A formula correlating the standing wave ratio caused by the bead and the physical parameters of the bead is derived. A bead of this type may be designed to have very low voltage standing wave ratio (VSWR) over a very wide band of frequency. A typical design using quartz and air as dielectrics is given, and the calculated VSWR is below 1.003 over a bandwidth whose maximum to minimum frequency ratio is as high as 13:1.

scholarly journals Theoretical and experimental studies of highly selective planar two-dimensional Bragg structures based on dielectric waveguides in the terahertz frequency range

2019 ◽  
Vol 30 ◽  
pp. 07009
Author(s):  
Naum Ginzburg ◽  
Nikolay Peskov ◽  
Vladislav Zaslavsky ◽  
Ekaterina Kocharovskaya ◽  
Andrey Malkin ◽  
...  
Keyword(s):  
Bragg Reflection ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Dielectric Waveguides ◽  
Two Dimensional ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Frequency Range ◽  
Three Dimensional Modeling ◽  
Bragg Structures

Based on theoretical approach and three-dimensional modeling using the CST Microwave Studio code, planar dielectric two-dimensional Bragg structures in terahertz frequency range were developed and manufactured. Proof-of-principle electrodynamic experiments on the “cold” testing of these structures were carried out. It is shown that the experimental results are in good agreement with the theoretical predicts, including the existence of the highest Q mode inside the Bragg reflection band in the absence of periodicity defects.

scholarly journals Features of electromagnetic wave propagation in two- and three-layer cylindrical dielectric waveguides

2019 ◽  
Vol 30 ◽  
pp. 06006
Author(s):  
Alexander G. Shein ◽  
Tatiana S. Kharlanova
Keyword(s):  
Electromagnetic Waves ◽  
Dielectric Waveguide ◽  
Electromagnetic Wave Propagation ◽  
Azimuthal Angle ◽  
Transverse Magnetic ◽  
Cylindrical Shape ◽  
Dielectric Waveguides ◽  
Power Flux ◽  
Open Dielectric Waveguide ◽  
Layer Waveguide

Various characteristics of electromagnetic waves propagating in two- and three-layer open-dielectric waveguide structures of cylindrical shape are studied. Parameters of wave components in separate areas of the waveguide are considered. Electrodynamic characteristics and frequency dependencies for several values of layer dielectric permittivity obtained during the study are analyzed. The corresponding graphs of dependencies are presented. The dependencies of the power flux density of transverse magnetic (TM) waves in two- and three-layer waveguide structures in the absence of field dependence on azimuthal angle are considered.

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