A slotted post-wall waveguide array with inter-digital structure for 45-deg linear and dual polarization

We propose a slotted post-wall waveguide array with an inter-digital structure for a 45° dual linear polarization antenna. Two arrays inter-digitally share the common aperture. The whole structure is fabricated perfectly in a single layer using post-wall waveguides. The unique difficulty for this array is that the adjacent waveguides for the same polarization are sparsely spaced by two times of the broadwall width. So, dielectric filling in the waveguide is indispensable for reducing the physical width of the waveguide and the resulting grating lobes. Another specific feature is that the two arrays are excited by traveling waves propagating in opposite directions. Five types of two-dimensional arrays were fabricated. The measurement results are reported.