M.B. Manuilov, G.P. Sinyavsky
A new rigorous full wave technique for analysis of rectangular waveguide antenna arrays with multi-layer finite flush-mounted dielectric cover has been proposed. The problem formulation takes into consideration the equally spaced antenna arrays of identical elements with rectangular or hexagonal grid, as well as unequally spaced arrays and combined arrays of waveguides with different dimensions.
The initial EM radiation problem has been reduced to the system of integro-differential equations for magnetic currents on the apertures of waveguides and dielectric cover. The system of integro-differential equations has been obtained using continuity conditions for tangential magnetic field components on the apertures. Galerkin technique with weighted Chebyshev and Gegenbauer polynomials were employed to solve the obtained system. These basis functions explicitly take into account the field asymptotic at the edges of apertures, thus the fast convergence of solution is achieved. The presented numerical results confirm the fast convergence of the method.
A parametric study of waveguide antenna arrays with finite multi-layer dielectric cover is considered, which includes the effect of dielectric cover on impedance matching, array efficiency and directivity. It was shown, that the wide-angle scanning arrays should have multi-layer dielectric cover with the number of layers no less than 2 for high impedance matching over operational frequency band. Moreover the permittivity of the lower dielectric sheet should be approximately equal to permittivity of the dielectric filling the waveguides. The electrical dimensions of two-layer dielectric covers have been evaluated for good impedance matching of arrays.