Broadband leaky wave antennas

An antenna comprises a conically shaped body of dielectric material. Cross-sections of the body have truncated elliptical shape, wherein each shape is truncated substantially through a first focus of the elliptical shape along a truncation line that extends substantially perpendicularly to a main axis of the elliptical shape. The second focus of the elliptical shape lies within the body. An elongated wave carrying structure such as a slot in a conductive ground plane extends substantially along a focal line through the first focus of the elliptical shapes in successive cross-sections. This structure supports transmission and/or reception over a wide range of frequencies. In an embodiment a multi-frequency feed structure is integrated in the ground plane of the antenna.