  In this paper the hp-version of the boundary element method is applied to the
electric field integral equation on a piecewise plane (open or closed)
Lipschitz surface. The underlying meshes are supposed to be quasi-uniform. We
use H(div)-conforming discretisations with quadrilateral elements of
Raviart-Thomas type and establish quasi-optimal convergence of
hp-approximations. Main ingredient of our analysis is a new
H^{-1/2}(div)-conforming p-interpolation operator that assumes only H^r \cap
H^{-1/2}(div)-regularity (r > 0) and for which we show quasi-stability with
respect to polynomial degrees.
