An antenna assembly is provided that may include an antenna element having first and second opposed sides. The antenna element may be configured to transmit or receive signals of a desired wavelength. The antenna assembly may also include a first conductive surface disposed proximate the first side of the antenna element and lying in a plane substantially perpendicular to the antenna element, and a second conductive surface disposed proximate the second side of the antenna element and lying in a plane substantially perpendicular to the first antenna element. The second conductive surface may be substantially parallel to, and spaced apart from, the plane in which the first conductive surface lies. Collectively the first and second conductive surfaces may be configured to excite wave propagation modes of a higher order than a fundamental propagation mode for reception or transmission of signals of the desired wavelength by the antenna element.