V. I. Dobisov1, N. V. Rastvorova2, A. M. Rudakov3, O. M. Terekhova4
1–4 JSC “V. Tikhomirov Scientific Research Institute of Instrument Design” (Zhukovsky, Russia)
Nonlinear losses, that means loss growth in ferrite devices with power increase of transmit microwave field, have connection with spin wave emergence.
Nonlinear losses emergence was with pulse power 2 kW in phase circulators of 3 mm-band waves which have the ferrite plates from 3SCh17, using in devices for a long time with (20…30) kW. Let's consider emergence possibility nonlinear losses using wave transformation H10 of primary (transmitted through the waveguide) microwave field, the front of which E H~ ~ is oriented orthogonally to the roll Z axis of the waveguide. For secondary field, fronts E H~ ~ are oriented orthogonally to the X- and Y-axes.
Under the influence of static magnetic field H0, magnetic ferrite shielding obtains tensor form to the linear polarization wave (H10 of microwave field) components. Under the influence of variable magnetic component ( H~ ) of wave H10, ferrite magnetization obtains variable component M~, precessing around the direction H0(M0) with microwave field frequency ω. Consequently, the linear polarized components of the microwave field ( H~X and H~Z ) are affected by ferrite, the total magnetization of which changes in a circle with t
the frequency of the microwave field, and its magnetic shielding is characterized by a tensor. As a result in the waveguide the secondary magnetic field ( H~X and H~Z ) components are excited. These components are both perpendicular to the magnetized field H0 and to the magnetic microwave field H~ component (components H~X and H~Z with 90° phase shifter).
According to the second Maxwell equation around this changeable magnetic field H~ , the magnetic field E~ obtains, turning in orthogonal direction ( H~ ) plane.
Secondary field components, established by tensor properties of magnetic ferrite shielding, are orientated by their local plane fronts (E~ H~ ) parallel to wide and narrow waveguide walls and perpendicular to H0 (Y-axis), and in YX-plane – perpendicular to X-axis. This components spread along the waveguide Y-axis (towards the wide walls E H~Z ~X ) and towards the narrow walls along the Xaxis E H~Y ~Z . Got the wide walls (field E HZ X ) and narrow walls (field E HY Z ), secondary fields induce currents on them, are reflected and spread to the opposite wall and etc. This transformation of fields orientation is only on the waveguide section, which have ferrite elements. The secondary waves don’t spread further along the waveguide. The current induced by these transverse fields on the waveguide walls, which have a final surface resistance, transforms into heat. If the ferrite or ferrite elements have irregularities (external elements, granulity, interstices, pinholes, roughness and etc.), ferrite sensibility increases to the magnetic field H~ . When the power of transmit waveform increases, M~ will increases too. Influence of ferrite on field components H~X and H~Z increases. Interaction of ferrite and magnetic field H~ increases. H~X and H~Z components and excited secondary fields E H~ ~ , spreading from one wall to another, are risen. This leads to increase of currents across them, to heating and increase in the resistance of the walls, to increase of energy consumption in the transmitted field for heating, to appearance and growth of nonlinear losses.
Dobisov V.I., Rastvorova N.V., Rudakov A.M., Terekhova O.M. Nonlinear losses in circulators. Antennas. 2021. № 5. P. 73–78.
DOI: https://doi.org/10.18127/j03209601-202105-08 (in Russian)
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