Double-Band Tunable Magnetic Conductor Realized by a Grounded Ferrite Slab Covered With Metal Strip Grating

The property of a perfect magnetic conductor (PMC) boundary is achieved at two frequency bands by using Faraday rotation in a grounded ferrite slab covered with a metal strip grating. The PMC boundary condition is obtained for the wave polarized perpendicularly to the strips. The two frequency bands correspond to 45 and 90 Faraday rotation across the slab, respectively. In the former case, the strip grating traps the incident rays inside the slab after one round trip in the slab. As a result, the incident ray performs two round trips inside the slab before exiting it. This provides the maximum possible Faraday rotation with the smallest possible slab thickness. The concept is demonstrated experimentally by placing the PMC structure along the sidewalls of a rectangular waveguide so as to produce a TEM wave.