N.F. Popova – Ph.D.(Eng.), Deputy Director for Research, 

NIKA-Microwave, Ltd (Saratov) 

E-mail: popova1946@mail.ru

V.P. Meschanov – Honored Scientist of RF, Dr.Sc. (Eng.), Professor, 

Director of NIKA-Microwave, Ltd (Saratov)

E-mail: nika373@bk.ru

Y.V. Turkin – Leading Engineer, NIKA-Microwave, Ltd (Saratov)  E-mail: turkin.yaroslav@gmail.com

In this article we theoretically investigate synthesis of thin film coaxial matched loads by the computational experimental method. Parameters of the coaxial matched load need to be satisfied in the frequencies interval form 0 to 50 GHz. Experimental stage has been changed to high-precision numerical modeling. Electromagnetic and heat transport problems have been incorporated in a single multiphysical model. Temperature distribution inside load parts is calculated from standard heat transport equation using Lagrange’s finite elements. Electromagnetic part of the problem is included via frequency-domain Helmholtz equation. Nonlinear system has been solved numerically with the self-consistent segregated iteration solver. Dirichlet boundary conditions for the temperature are used to take into account contact of the impedance transformer with other massive parts of the load’s body. Neumann boundary conditions are used on the surface of transformer to model convective heat exchange between the massive body of the load and environment. Resistive films included into electrical part of the multiphysical problem via surface impedance boundary condition to evade problems in mesh generation. Scattering matrix formalism and mode-matching technique are used to roughly estimate electrical characteristics on every iteration of computational experimental method. Synthesis process ended on 5th iteration and coaxial load met all requirements: VSWR limited by value 1,2 and maximum temperature of the dielectric substrate was about 35-38°C. Also we have investigated the role of the substrate material: temperature of Aluminum Nitride dielectric substrate was about 10°C higher than Silicon Carbide substrate. Obtained results allow us to conclude that our modification of computational experimental method could be successfully used for the fast numerical synthesis of high-power microwave components.

Popova N.F., Meschanov V.P., Turkin Y.V. Synthesis of thin-film coaxial matched loads with experimental optimization method and multiphysical models. Radiotekhnika. 2020. V. 84. № 7(14). P. 34−. DOI: 10.18127/j00338486202007(14)-05.

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