Patent ID: 7889148

Claim:
A plane wave antenna comprising: a horn antenna; a layered waveguide at least partially inside the horn antenna, wherein the layered waveguide comprises: a central dielectric slab increasing in width toward the horn antenna and forming a first layer of the layered waveguide, the central dielectric slab with a first dielectric constant, a second slab forming a second layer of the layered waveguide, the second layer adjacent to the central dielectric slab, the second slab with a second dielectric constant smaller than the first dielectric constant, and a third slab forming a third layer of the layered waveguide, the third layer adjacent to the central dielectric slab such that the central dielectric slab is between the second and third slabs, the third slab with the second dielectric constant; and wherein the central dielectric slab has a substantially constant thickness less than a quarter of a wavelength at a highest frequency of operation of the plane wave antenna.