Radiofrequency transmission device comprising a fastening element forming a radiating portion of an antenna
The invention relates to a radiofrequency transmission device comprising an electrical board, a transmission line, and an electroconductive fastening element which is intended to fasten the electrical board to a support, the transmission line being electrically coupled to the fastening element such that the fastening element forms at least one first radiating portion of an antenna arranged so as to emit and/or receive radiofrequency signals travelling along the transmission line.
1. An RF transmit/receive device comprising a circuit card, a transmission line, and an electrically conductive fastener element for fastening the circuit card on a support, the transmission line being electrically coupled with the fastener element so that the fastener element forms at least a first radiating portion of an antenna arranged to transmit and/or to receive RF signals conveyed along the transmission line, the circuit card further comprising a first antenna track connected to the transmission line and electrically coupled with the fastener element, the first antenna track forming a second radiating portion of the antenna,
wherein the transmission line extends on an insulating layer of the circuit card within a ground surface, whereas the first antenna track extends on the insulating layer without being surrounded by the ground surface.
2. The RF transmit/receive device according to claim 1 , wherein the circuit card includes a first surface formed on a conductive layer and a second surface formed on an insulating layer, the first surface being the ground surface, the fastener element extending from or through the second surface.
3. The RF transmit/receive device according to claim 2 , wherein the transmission line is a transmission-line track of the circuit card that extends from within the first surface to the second surface in order to form the first antenna track that extends within the second surface to the proximity of the fastener element.
4. The RF transmit/receive device according to claim 3 , wherein the antenna is a monopole antenna.
5. The RF transmit/receive device according to claim 2 , wherein the circuit card includes a second antenna track that extends within the second surface, that is connected to the first antenna track, and that forms a third radiating portion of the antenna.
6. The RF transmit/receive device according to claim 5 , wherein the antenna is a planar inverted-F antenna.
7. The RF transmit/receive device according to claim 1 , a resonant frequency of the antenna being defined in particular on the basis of a length of the fastener element.
8. The RF transmit/receive device according to claim 7 , wherein the resonant frequency of the antenna is also defined on the basis of a length of the first antenna track and/or of a length of the second antenna track, and thus of at least one dimension of the second surface.
9. The RF transmit/receive device according to claim 1 , wherein the fastener element extends through a metal-lined hole-formed in the circuit card, the first antenna track or the second antenna track being connected to the metal-lined hole.
10. The RF transmit/receive device according to claim 1 , wherein the antenna is a Yagi type antenna, and wherein the fastener element acts as a reflector element of the Yagi antenna.
11. The RF transmit/receive device according to claim 1 , wherein the fastener element is a screw.
12. Electrical equipment including the RF transmit/receive device according to claim 1 .
13. The electrical equipment according to claim 12 , the support of the circuit card being a housing of the electrical equipment.