Waveguide Filters

The most investigated planar waveguide filters are E plane filters. These structures are designed by means of classical microwave circuit techniques and they are accommodated along the waveguide direction.
However, despite they are a well established technique for realizing mass producible microwave configurations, E-plane filters suffer from bulky size and stop-band performance that may often be too low and too narrow for many applications. Moreover, standard manufacturing techniques for these filters involve machining the waveguide halves.
A low cost waveguide filter can be realized by transversally accommodating one or more Frequency Selective Surfaces (FSSs) inside of a waveguide. Such a solution presents the advantage of being very compact, lightweight and easy to be fabricated. Moreover, the filter can be accommodated in the waveguide by simply screwing them on the flange.