Low-Pass, Quasi-Optical Filters for Oversized or Focused-Beam Waveguide Applications

At this time there is increasing interest in microwave and millimeter-wave systems which use quasi-optical propagation. Examples are focused-beam waveguides and oversized metal waveguides, both of which permit high power carrying capability and low transmission losses. To date most of the research on filters for such systems has been based on the use of dielectric layers of differing dielectric constants. This paper describes a new type of low-pass structure capable of a broad stop band such as would be required in many practical quasi-optical systems. This structure is similar in some respects to the artificial dielectric structures used in some lens antennas.