Complex directional antenna consists of separate near-omnidirectional antennas (radiating elements) positioned in the space and driven by high-frequency …
The aim of the research is the development of the theory, analysis methods, characteristic assessment and the creation of sample small broadband high–tech antenna elements and screens of various patterns in order to minimize errors in positioning by GNSS signals.
According to the above aim, the following tasks are formulated and solved in the paper:
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Developing the theory, analysis methods and examples of low–profile broadband plate antennas with a base consisting of artificial insulators replacing the traditional printed–circuit constructions.
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Developing the principles of constructing and creating sample broadband three–dimensional antennas with circular polarization and the overall size of tenths of the wavelength.
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Making engineering evaluations and analyzing the characteristics and potential of plane conducting and impedance screens and also screens made of composite materials, including screens in the resonant frequency range.
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Creating sample high accuracy positioning antennas and antenna units in integrated navigation receivers.
Scientific novelty:
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The basics of the theory of low-profile broadband plate antennas with a base consisting of artificial insulators in the form of the periodic structure of the elements with a short pitch as compared to the wavelength have been developed. The conditions when there is no considerable normal dispersion in technologically implemented bases have been discovered. The effect of bandwidth expansion when a base in the form of periodic slow–wave structure located along the plate perimeter used has been discovered. Sample antennas working in the entire range of GNSS frequencies with bases produced with the economical methods of casting and stamping have been developed.
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The effect of considerable bandwidth expansion in plate structures in case of capacitive coupling between plates and between plates and the screen has been discovered and explained. The optimal height of the plate for two–dimensional approximation and the optimal radius of the spherical carrier in a three–dimensional structure have been evaluated. Sample structures with the passband of more than 40% and the dimensions of about one third of the wavelength relative to the lower frequency of the range have been created.
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An approximation closure for the current induced by an omnidirectional source on a plane conducting screen has been constructed. The validity limits of this closure have been studied by comparing it with the precise numerical solution. The engineering evaluations of directivity characteristics and backscattered patterns formed by the plane conducting screen induced by an omnidirectional source, by a source with low directivity and also by a source with a tabletop radiation pattern have been obtained.
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An approximation closure for the current induced by an omnidirectional source on a plane conducting screen has been constructed. The validity limits of this closure have been studied by comparing it with the precise numerical solution. The engineering evaluations of directivity characteristics and backscattered patterns formed by the plane conducting screen induced by an omnidirectional source, by a source with low directivity and also by a source with a tabletop radiation pattern have been obtained.
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The asymptotic evaluation of the directivity characteristic and backscattered radiation patterns for antennas on plane screens of the impedance type has been made.
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The distribution function for equivalent electric current of a semitransparent composite screen at any distances from the source has been constructed. It has been shown that the characteristics of a semitransparent screen weakly depend on the phase (character) of equivalent impedance provided that this impedance is not inductive. It has been shown that there is optimal layer impedance providing the best backscattered radiation pattern for a screen of a certain size. The evaluations of radiation pattern and backscattered radiation pattern for practically implemented structures have been obtained.
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Experimental and production high accuracy positioning antennas have been developed.
The methods and approaches developed in the paper have been used to create high accuracy positioning antennas and antenna units in integrated navigation receivers that are mass–produced and registered by the International GNSS Service, including: Topcon PGA5 (L1 GPS/GLONASS) with slot induction; Topcon PGA1…PGA3 (L1,L2 GPS/GLONASS) and antennas in integrated receivers of the Hiper family; the antenna unit of the Topcon GMS–2 (L1 GPS/Omnistar) receiver for GIS purposes; Topcon MGB6 (L1 GPS/GLONASS/OMNISTAR/Beacon) for GIS purposes; Topcon CR–G3, PG–A1 and the antenna unit of the GR3 (L1/L2/L5 GPS/GLONASS) receiver; the antenna unit of the integrated all–pass GPS/GLONASS/GALILEO/Omnistar/BEACON Topcon Trupath receiver of the automatic agricultural machinery control system.
Main propositions presented for the defense:
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The methods of constructing low–profile circular–polarization broadband plate antennas with bases consisting of artificial insulators made of metal using the methods of casting and stamping and also three–dimensional broadband plate structures of a small electric size.
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The theory of reducing the multipath propagation error by the screens of various types of high accuracy positioning antennas.
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The engineering methods of calculating and designing antennas of the abovementioned type.
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