In two earlier papers [1], [2] the diffraction of a surface wave by a fight-angle wedge was treated; one face of this wedge is perfectly conducting and the other is reactive. It was pointed out that the Kirchhoff theory of diffraction provides a useful approximation here. A readily calculable result has not been obtained for wedge angles other than

, so the diffraction patterns for various wedge angles are calculated here by the Kirchhoff approximation and compared with some measured patterns of a wedge excited by a very narrow H-plane sectorial horn. Both the calculated and measured patterns show that in general the wedge angle has a relatively small effect on the diffraction pattern of a loosely bound surface wave, except when the wedge angle is close to

.