An antenna array assembly comprises a ground plate, a linear array of patch radiator elements disposed in a spaced parallel relationship with a first face of the ground plate, and a first, second, third and fourth elongate passive radiator, each comprising one or more substantially planar conductive parts which are electrically isolated from the ground plate. The first and second elongate passive radiators are disposed symmetrically on either side of the linear array and parallel to a centre line of the linear array, on the same side of the ground plate as the linear array. The third and fourth elongate passive radiators are disposed further from the linear array than are the first and second elongate passive radiators. Each of the third and fourth elongate passive radiators is narrower than and projects further from the ground plate than does each of the first and second elongate passive radiators.