Surface Wave Radiation from an FSS

Surface waves on a finite FSS will radiate just like the Floquet currents will radiate. These matters—and, in particular, how they are being excited—will be the subject of detailed discussions in Chapter 4. It suffices in this introduction to present a typical example as shown in Fig. 1.4. We show here 25 columns with the same element dimension as earher (see insert). The angle of incidence is 

5° as also indicated in the insert. The Floquet currents alone are producing a bistatic scattering pattern as indicated by the full line in Fig. 1.4 (this corresponds to simple truncation of an infinite FSS). Also shown is the bistatic scattering pattern as obtained by using the total currents on the finite FSS—that is, the sum of the Roquet currents, the two surface waves, and the end currents as obtained by direct calculation from the SPLAT program (see the broken line pattern). The pattern obtained from the Floquet currents only are of course merely a pattern of the sinx/x type. However, when using the total calculated current we observe 

---