Hard surfaces obtained by using microstrip resonators

Hard surfaces allow the tangential component of the electric field not to go to zero along the surface. However, previous realizations have required a dielectric slab thickness that is of the order of d/spl ap/ /spl lambda//(4/spl radic/(/spl epsiv//sub r/-1)). This paper will show that the hard surface boundary condition can be obtained for d/spl Lt//spl lambda/ by using printed scatterers that are resonant near the frequency of operation. A printed cross array geometry that produces a hard surface for all polarizations is illustrated.