B. Horsfield et Jar. Ball, Surface-wave propagation on a grounded dielectric slab covered by a high-permittivity material, IEEE MICR G, 10(5), 2000, pp. 171-173
A grounded dielectric slab covered by a higher permittivity material would
not normally be expected to support surface waves. This conclusion must be
modified when the covering material is sufficiently lossy. Assuming a thin
slab, approximate analysis shows that the fundamental TM0 surface wave is a
ble to propagate if the cover loss is high enough, A numerical analysis has
verified these conclusions. Propagation of higher order TM and TE modes Is
found to be possible above cutoff frequencies, which reduce as cover loss
is increased. These results are of significance when printed circuit transm
ission lines such as microstrip or slotline are used as contact sensors, e.
g., for moist materials.