A.A. Skvortsov – Ph.D.(Eng.), Associate Professor, 

Department «Radio and Telecommunications», Yuri Gagarin Saratov State Technical University of Saratov E-mail: sotrudniki.1@yandex.ru

Presently coaxial-sector waveguide (CSW), featured some advantages in comparison with transmission lines of simple cross section, finds application as a basic unit of such microwave systems as UHF-devices for thermal processing of dielectric materials, reflecting 2D grids and etc. Calculation of CSW dominant mode cutoff wavelength is an important electrodynamic task arising by development of UHF-devices on pieces of analyzed transmission line. Moreover, since such devices, as a rule, operate in single-wave mode, determination of cutoff wavelength of the first high-order mode of CSW is of practically interest. Information about this parameter is necessary to calculate the broadbandness coefficient of considered waveguide structure. Wave impedance is one more important electrodynamic parameter of CSW, knowledge of which is useful in solution of the problem of matching UHF-networks, analysis of reflections from singularities, calculation of transmission coefficients of stub branchings of microwave devices and so on. It is necessary to mention that evaluation of practical applicability of this or that waveguide plumbing is directly linked with determination of it power handling capability and attenuation of electromagnetic waves in it. Analysis of fields of EM waves propagating in CSW has shown that given transmission line (TL) can be considered as rectangular waveguide (RW) rolled in transverse plane along circle arc. Considered model has allowed to obtain expressions for determination of cutoff wavelengths of the dominant and the first high order modes, bradbandness coefficient, wave impedance, power handling capability and attenuation coefficient in metallic walls of CSW by using known expressions for definition of corresponding electrodynamic parameters of RW. Quasi-analytical calculation of electrodynamic parameters of CSW at different values of it geometrical sizes, electro physical parameters of homogeneous dielectric filling and operating wavelength has been carried out by using formulas obtained on a basis of proposed model. The results of quasi-analytical calculations have been compared with data obtained by the finite element method to verify their correctness. Comparison of the results of calculations of electrodynamic parameters of CSW obtained by using a quasi-analytical technique and the FEM has shown their good agreement. So, quasi-analytical expressions considered in the present work, has allowed determine dependences of the cutoff wavelengths of the dominant and the first high-order modes, broadbandness coefficient, wave impedance, power handling capability and attenuation coefficient in metallic walls of CSW versus its geometrical sizes, electro physical parameters of homogeneous dielectric filling and operating wavelength, which can be used successfully in building UHF-devices of diverse application performed on a basis of considered TL. It is necessary to mention also that obtained quasi-analytical expressions can be adapted for calculation electrodynamic parameters of CSW with different dielectric filling.

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