Broadband antenna

A broadband antenna includes a substrate having a first surface on which a first radiator arm, a second radiator arm, a first connecting conductor and a first grounding section are disposed, and a second surface on which a second connecting conductor and a second grounding section are disposed. The first connecting conductor has one end connected to a junction at which the first and second radiator arms are interconnected, and has another end connected to the first grounding section. The first connecting conductor has a feed-in point disposed thereon. The second connecting conductor has one end connected to the second grounding section. Moreover, at least a portion of the first connecting conductor overlaps with a projection of the second connecting conductor onto the first surface so that transmission directions of signals in the first and second connecting conductors are the same.