Several internal and external problems of electrodynamics on excitation and radiation of electromagnetic waves by a single slot and systems of narrow transversal circumferential and arc slot cut in the outer conductor of the coaxial line have been solved by induced magnetomotive forces method, Galyorkin method, and method of moments. The problems have been solved under the conditions of arbitrary geometric parameters of the feeder and radiators, the final termination of the coaxial line, and the electrophysical characteristics of the inner and outer spaces of the coaxial line.
Electromagnetic characteristics of the following structures are studied: single transversal arc slot, single transversal circumferential slot, system of transversal arc slots, and system of transversal circumferential slots, cut in the outer conductor of the coaxial line with an arbitrary end load. The research was carried out in a multiparameter formulation of the problem with a wide range of variations of all geometric and electrophysical parameters of structures in a wide range of wavelengths.
Physical laws connecting the coefficients of radiation and reflection, slot conductivity, amplitude-phase distributions of the field of the radiating aperture, and radiation patterns of these coaxial-slot structures with the sizes of slot elements, radii of feeder conductors, dielectric characteristics of inner and outer volumes, the positions of the slots in the system, and the parameters of the end-load of the cable in a wide range of wavelengths are determined.
It is shown that the range of wavelengths at the half power level of the arc slot radiation coefficient in the infinite coaxial line reaches 50% ÷ 60%, depending on the slot length.
It is established for the first time that if the resonant wavelength of the arc slot is in the multimode range of feeder wavelengths, this leads to decreasing of the radiation coefficient and distortion of the dependence curve of the radiation coefficient on the wavelength. To avoid this effect, approximate relations connecting the radii of the coaxial line to the length of the radiator have been obtained.
Also, it is established that the nature of the radiation of a single circumferential slot in the outer conductor of an infinite coaxial line is nonresonant, so the level of the radiation coefficient cannot reach 0.5 on any conditions. It is shown that a narrow circumferential slot in the shield of a coaxial line is able to radiate efficiently at any wavelength, and its radiation coefficient is limited only by the parameters of the feeder and media.
It has been found that in the case of radiation in a material medium with high dielectric constants, the radiation pattern of the slot array has a frequency-independent main lobe whose shape and direction are constant. It is established that in certain cases of calculating the energy characteristics of the coaxial-slot system radiating into the medium with a large loss, it is possible to neglect the interaction between the radiators located at distances greater than a quarter wavelength which significantly decreases the calculation time.
For the first time, a method of controlling the characteristics of a coaxial-slot antenna array is realized: the forming a system of arc slots with nonregular radiator lengths, whose radiation coefficient is more than 0.95 in a wide range of operating wavelengths (44%), amplitude distribution, being constant or decreasing to both ends of the array, and the level of the side lobes of pattern does not exceed 0.15.
It has been found that in a semi-infinite coaxial line, the range of working wavelengths of a single arc slot above the level of the radiation coefficient 0.9 can achieve 42%. Supertiny circumferential slot (length 3.8 mm) in relation to the wavelength keeps a high radiation coefficient (above 0.9) for wavelengths from 130 mm up to 300 mm when the distance from the slot to the end wall less than 0.1 of wavelength.
Mathematical models of coaxial-slot radiating structures and computing programs that allow a multiparametric analysis of physical properties of fields in structures of this kind, as well as identified patterns of frequency-spatial and frequency-energy characteristics of these fields are the basis for creating radiating devices of high-quality new electrodynamic characteristics.
The results of the dissertation can be applied in the creation of new or improving current wireless communication systems, including those in hard-to-reach places, detection systems, diagnostic and medical equipment, in particular, such as irradiators for interstitial hyperthermia.
