The invention provides a lighting device (104) and a luminaire (200). The lighting device comprises a light emitter (110) thermally connected to a heat sink (120). The lighting device further comprises a communication circuit (130) coupled to the heat sink for transmitting and/or receiving a communication signal. A first conductive part (122) of the heat sink comprises at least a first pole (142) of a dipole antenna (140) for transmitting and/or receiving the communication signal via the heat sink. This first pole of the dipole antenna may be induced via a primary radiator (160) to activate the gap (170).

A wireless communication device for use in a load control system for controlling one or more electrical loads may comprise a counterpoise, a first and second antennas, a RF communication circuit and a control circuit. The two antennas may be oriented differently and spaced apart from each other. For example, the first antenna may extend perpendicularly from the counterpoise while the second antenna extends in a plane substantially parallel to the counterpoise. The first antenna may extend from the counterpoise at a point substantially central to the counterpoise while the second antenna may extend along a perimeter of the counterpoise. The RF communication circuit may transmit wireless signals via the first and second antennas. The control circuit may cause the RF communication circuit to transmit a first wireless signal in a first time slot and a second wireless signal in a second time slot.

An antenna substrate includes a baseplate, a first radiation electrode, a second radiation electrode disposed on the baseplate spatially apart from the first radiation electrode in a second direction (X), and a ground portion that is disposed on the baseplate and that is common to the first and the second radiation electrode. The ground portion includes a ground electrode that faces the first radiation electrode when seen from the first direction (Z), a connection line between the first radiation electrode and the second radiation electrode when seen from the first direction and that has a size that is smaller than a size of the ground electrode in a third direction (Y) orthogonal to the second direction when seen from the first direction (Z), and a stub.