A radial line slot antenna for 12 GHz satellite TV reception

The analysis and design of novel planar antennas which can radiate circularly polarized pencil beams in -band are presented for the application of receiving direct broadcast from a satellite (DBS). This antenna belongs to a class of slotted waveguide antennas and high efficiency is expected in principle. A circular two-dimensional aperture is located on the top plate of a twofold radial waveguide and is excited by a radially inward traveling transverse electromagnetic (TEM) mode in the upper waveguide. Slots are arrayed on the aperture spirally in such a way that they can couple with the radial currents flowing over the aperture plate to produce a circularly polarized broadside beam. Promising performances of the antenna are predicted theoretically. Experiments are performed with respect to basic characteristics of the antenna and they show the validity of the design and analysis.