Polarization Dependent Coupling of Two Flange Mounted Rectangular Waveguide Radiators

It is known that a noticeable polarization "squint" takes place in a small array of flange mounted rectangular waveguide radiators. Cross-polarization (i.e. coupling of the Ey polarized incident field with Ex is present even in a single waveguide radiator in order to satisfy the edge and boundary conditions. When two waveguides mounted on the same flange are closely spaced both polarizations couple in different ways. Relative strenghts and phases depend on the relative position of the two radiators. In this contribution, we analyse rigorously the single and twin radiating waveguides by means of a variational approach which includes the edge conditions on the apertures from the start. This has an important bearing on rate of convergence and accuracy vs. matrix size, enabling us to obtain highly accurate solutions. Theoretical and experimental results are compared for the two important cases of two radiators with parallel narrow wall and with parallel broad wall.