Effect of obstacle profile on knife-edge diffraction

Experimental studies on the effects of the profile of a dominant obstacle on the diffraction of electromagnetic waves are described. A comparison of the distribution of diffracted power behind triangular (both symmetrical and nonsymmetrical) knife edges and semicircular knife edges shows some important practical features. In contrast to the case of a horizontal obstacle, the transverse profile of the triangular obstacle determines the optimum receiving site and relatively small changes in receiver location can result in substantial changes in received power. On the other hand, the semicircular knife edge can be adequately described in terms of a rectangular (
180\deg
) knife edge. In no case is an effect on the far field due to the polarization of the incident fields apparent.