We report an experimental and theoretical investigation of a 4-port resonan
t switch patterned in a two-dimensional (2-D) metallic photonic lattice. Fo
ur-port measurements of scattering parameters are carried on in the 22-40-G
Hz frequency band. They show quasi-full lateral transfers, with or without
reversal of propagation direction of electromagnetic wave, which are interp
reted in terms of multimode propagation phenomena within the coupling regio
n. Experimental data are explained by the solution of a suitable form of th
e 2-D Helmholtz equation for metallic propagation media.