Characterization of diffraction anomalies in 2-D photonic bandgap structures

This paper deals with transmission anomalies of freestanding two-dimensiona l bandgap structures, which have found a large application range as filter and guiding structures in communication systems and radioastronomical appli cations in the far infrared region. The effect appears as a sharp breakdown of the transmission factor in the passband of quadratic patch and slot str uctures, first revealed by measurements. This paper outlines the numerical confirmation of these effects by computer simulations based on the method o f moments combined with the Floquet theorem. The transmission and reflectio n behavior is examined for different structure geometries, frequency ranges , angle, and polarization of the incident wave also revealing alternative s tructures suppressing these effects. The modeling with electric and magneti c currents allows the characterization of both patch and slot arrays. Final ly, cross shaped structures are examined allowing the complete suppression of this kind of anomalies.