Backscattering from tapered resistive strips

Resistive strips have lower backscattering cross sections than perfectly conducting strips, and this is true in particular when the illumination is edge-on with the electric vector parallel to the edge. The scattering then consists of edge contributions and attention is confined to this case. Using the available expressions for the edge contributions of uniform resistive strips it is shown that the front edge scattering decreases with increasing resistivity, whereas the rear edge scattering increases. This suggests that the resistivity should be tapered from a maximum at the front to zero at the rear, and numerical results are presented for the particular case of quadratic (parabolic) tapers. Values for the front and rear edge contributions are extracted from the scattered field data, and for strips more than about a half-wavelength in width it is found that the front edge contribution is almost identical to that for a uniform resistive half-plane. An empirical expression for the rear edge contribution is also derived, and the implications of the results are examined.