impedance boundary conditions
anisotropic conductivity boundary conditions
antenna with built-in polarizator
Yu.V. Yukhanov, A. I. Semenikhin, D. V. Semenikhina, N. I. Bobkov
In the article the transmission-type multilayer polarization rotators on frequency band of the 2…18 GHz are designed on the basis of impedance method, comparison of their numerical and experimental characteristics is carried out and examples of the using of designed polarizators in apertures of horn antenna and of the biconical antenna are given.
Planar layered model of anisotropic polarization structure (PS) including system of the uniform isotropic magneto dielectric layers with different thickness and relative permittivity and relative permeability is considered. Between layers (inwardly PS) thick grids of con-ductors with different tilt angles of conductor orientation in nearby grids are found. The Influence of the conductor thickness is taken into account by modeling of each grid by two ideal linear polarizators in the manner of two anisotropic conducting surfaces tangent to upper and lower parts of the grid and having equally oriented axis to anisotropies. On these two surfaces are assigned Vladimirsky boundary conditions to anisotropic conductivity . The equivalent impedance characteristics of whole layers' systems of the PS are de-termined.
Some calculation results of the frequency characteristics of reflection ratio , transmission ratio , voltage standing-wave ratio (VSWR) of the multicascade symmetrical PS with foam separator of alike thickness and alike difference tilt angles of the grids in nearby cascade are brought . Quantity of the cascades and thickness of the separators were optimized for ensuring the tuning of polarization plane of the refracted wave on corner 45 or 90 degree within frequency band 2 ...18 GHz with level of total insertion losses not more than 1,5 db. Quantity of the cascades and thickness of the separators were optimized for ensuring the rotation of polarization plane of the refracted wave in corner 45 or 90 degree within frequency band 2 ...18 GHz with level of total insertion losses not more than 1,5 db. The comparison of known accounting and experimental data and numerical result receiveing us for three-grid models PS has shown their good coincidence.
The models of the eight-grid and four-grid polarizators providing polarization rotation , accordingly, on angles 90 and 45 degrees on frequency band of the 2...18 GHz are made. The Experimental results have confirmed efficiency of PS designed model. The designs of the horn broadband antenna and biconical broadband antenna with built-in polarizators in apertures are brought.
The measurements of patterns on frequency band of the 2...18 GHz have shown that presence of polarizator in aperture does not bring about observable change of horn pattern. The polarizator Losses do not exceed of 0,3 db ; VSWR goes up to 1,6 in contrast with 1,52 without of polarizator . The polarizator accommodation in aperture of biconical antenna enlarges azimuthal pattern unevenness before 3,5 db in upper cutoff frequency ; antennas' VSWR does not exceed 2,5.