Abstract: Apparatus for transferring electromagnetic signal energy between a signal circuit and an antenna that extends outwardly from a ground-plane surface includes a conductive shield that substantially encloses the antenna to confine the signal energy and to exclude all others. The shield has an open end to admit the antenna and suction-cup means disposed around the opening to mechanically connect the apparatus to the surface. A plug of dielectric material inside the open end includes a through passage and a recessed portion that conforms to a base of the antenna and operates to align the antenna within the shield. Conductive mesh lines the recessed portion and is electrically connected to the shield. Flexible contacts extend inwardly from the shield and engage mounting screws in the antenna base to electrically connect the shield to the surface.