Lighting device with slot antenna
A lighting device ( 1 ) is disclosed. The lighting device ( 1 ) comprises: a communication unit ( 10 ) for wireless communication between the lighting device ( 1 ) and an external device; a solid-state lighting element ( 3 ) electrically connected to the communication unit ( 10 ); a heat sink ( 5 ) in thermal contact with the solid-state lighting element ( 3 ), the heat sink ( 5 ) having a slot ( 5 a ) adapted to act as a slot antenna; and a feed antenna ( 11 ) electrically connected to the communication unit ( 10 ), the feed antenna ( 11 ) having at least one end tip arranged at the slot ( 5 a) so as to enable the feed antenna ( 11 ) and the slot ( 5 a ) to communicate by proximity coupling.
1. A lighting device comprising:
a communication unit for wireless communication between the lighting device and an external device;
a solid-state lighting element electrically connected to the communication unit;
a heat sink in thermal contact with the solid-state lighting element, the heat sink having a slot adapted to act as a slot antenna; and
a feed antenna electrically connected to the communication unit, the feed antenna having at least one end tip arranged at the slot so as to enable the feed antenna and the slot to communicate by proximity coupling, and,
wherein the feed antenna is a dipole antenna having two end tips located at the slot, and the slot is aligned with a gap between the two end tips.
2. The lighting device according to claim 1 , wherein the heat sink is cylindrical.
3. The lighting device according to claim 1 , wherein at least a portion of the feed antenna is curved and includes the at least one end tip.
4. The lighting device according to claim 2 , wherein said portion of the feed antenna is arranged along a curved inner side wall of the cylindrical heat sink.
5. The lighting device according to claim 4 , wherein the at least one end tip is situated in an imaginary sector defined by a central longitudinal axis of the cylindrical heat sink extending from the axis to the middle of the slot and 100%-125% of the width of the slot.
6. The lighting device according to claim 3 , wherein said portion of the feed antenna does not cross the slot.
7. The lighting device according to claim 1 , further comprising a circuit board.
8. The lighting device according to claim 7 , wherein the feed antenna is printed on two opposite sides of the circuit board.
9. The lighting device according to claim 7 , wherein the circuit board comprises a ground plane, and wherein the slot is aligned with a gap between the end tip of the feed antenna and the ground plane.
10. The lighting device according to claim 1 , wherein the complete slot is provided in a curved side wall of the cylindrical heat sink.
11. The lighting device according to claim 1 , wherein the slot is L-shaped.
12. The lighting device according to claim 11 , further comprising a connector for mechanically and electrically connecting the lighting device to a light socket, wherein a bottom of the L-shaped slot is proximal to the connector.