Patent Application
20150091763
The present invention relates to an antenna assembly for an electronic device. Particularly but not exclusively the invention relates to an antenna assembly for a wireless electronic device such as an internet gateway, decoder or other network wireless device, or a mobile device such as a “smartphone”, tablet or similar device. In an embodiment of the invention a slot-antenna integrated into a mechanical part of an electronic device. The invention further relates to a terminal device or communication apparatus comprising such an antenna assembly.
Communication devices used in networks such as gateway devices for connection to the internet or wireless communication systems are increasingly multi-mode and multi-standard devices. Consequently such devices require the use of several different antennas integrated into the one device. The inclusion of several antennas in a device of reduced dimensions increases the mechanical constraints and performance. Indeed, the antennas should be able to operate in the presence of many mechanical parts and electrical components that may interfere with their radiation performances. Moreover, the location of the antennas in the device is also a challenge. With respect to radiation performance, there is a need to resolve isolation problems between radio frequency systems operating in different frequency ranges. Hence, a low ECC (envelope correlation coefficient) is used in MIMO systems (Multiple Input Multiple Output), the antennas of the MIMO systems being strongly isolated to respond to the maximum capacity of the channel used. Moreover, antenna gain is a key parameter in the performance of wireless systems. In addition, the cost of producing antennas is also an important factor to take into account. The present invention has been devised with the foregoing in mind.
A first aspect of the invention provides an antenna assembly for an electronic device, the antenna assembly comprising a conductive structure for housing at least a circuit board of the electronic device, an antenna formed as a slot in the conductive structure, a feeding element for feeding the antenna by electromagnetic coupling, the feeding element being positioned between the conductive structure and the circuit board of the electronic device and orientated to cross said slot, the feeding element being connected to a feed line on the printed circuit.
In an embodiment, the slot comprises a first radiating part and a second excitation part extending from the first radiating part, the second excitation part being configured to electromagnetic couple with the feeding element.
In an embodiment, the housing comprises a base plate forming the base of the conductive structure and a side plate forming a front side of the conductive structure, the first radiating part of the slot being formed in the front side of the conductive structure and the second excitation part of the slot being formed in the base plate of the conductive structure.
In an embodiment, the first radiating part has a tapered shape tapering inwards towards the second excitation part. In an embodiment, the second excitation part has a linear shape.
In an embodiment, the feeding element is orientated to extend across the second excitation part of the slot.
In an embodiment, the excitation part of the slot and the feeding element are positioned over corresponding openings in a ground plane of the circuit board.
In an embodiment, the feed element is positioned at a predetermined distance from the conductive structure and the circuit board, respectively.
In an embodiment, the feed element is held in position by a spacer made of insulating material.
In an embodiment, the excitation slot extends from the front side linearly along the base plate.
In an embodiment, the conductive structure forms a ground reference plate for electronic components of the electronic device.
A second aspect of the invention provides an electronic communication device comprising an antenna assembly comprising a circuit board provided with a feed line, a conductive structure for housing the circuit board, an antenna formed as a slot in the conductive structure, a feeding element for feeding the antenna by electromagnetic coupling, the feeding element being positioned between the conductive structure and the circuit board and orientated to extend across said slot, the feeding element being connected to the feed line on the printed circuit.
In an embodiment the printed circuit board comprises a ground plane, the ground plane being provided with openings positioned in alignment with the feeding element and the second excitation part of the slot.
In an embodiment the electronic device is a gateway device or a set top box.
In embodiments of the invention a slot antenna is integrated in conductive material of the housing or ground reference plate of an electronic device. The radiating element is excited from a printed circuit board of the electronic device by using a contact-free interface.
A further aspect of the invention provides an antenna for electronic device comprising at least one housing in a conductive material and a printed circuit board with a ground plane, characterised in that the antenna is formed by a slot realised in said housing in conductive material, the antenna being supplied by electromagnetic coupling using a conductive strip positioned between the housing in conductive material and the printed circuit board so as to cross said slot, the strip being connected to a feeder line realised on the printed circuit and the ground plane having an opening with respect to the slot and the strip.
In an embodiment of the present invention, the strip is held at a predetermined distance, from the housing and the printed circuit board respectively.
In one embodiment, the strip is held in position by a spacer made of insulating material.
In an embodiment, the housing is formed by a first plate with at least one second plate connected to said first plate. The slot is produced in said second plate by extending into said first plate.
A further aspect of the present invention relates to a communication terminal comprising at least one antenna according to any embodiment of the first aspect of the invention.
Embodiments of the invention will now be described, by way of example only, and with reference to the following drawings in which:
An embodiment of the present invention will be described by referring to an electronic device for a domestic network operating in the 2.4 GHz band. It will be appreciated that the invention is not limited to this specific type of device and may be applied to any wireless communication device. In the exemplary electronic device, a metal plate structure may be typically used as shielding and/or as a ground reference plate. The role of this metal plate structure is to obtain the electromagnetic compatibility of the electronic device that includes multiple electronic components, connectors and other circuits. The metal plate structure is used as ground reference for the elements and can reduce interfering signals. Embodiments of the present invention use this metal plate structure to produce a slot-antenna and supply this antenna by means of a contact-free interface.
The ground plane of the PCB 3 is provided with openings 3a, 3b located in correspondence respectively with the excitation slot 2b and the feeding strip 4.
The simulation of an antenna in accordance with the described embodiments was realised in the Wi-Fi band of frequency 2.4 GHz. For this simulation the 3D electromagnetic tool HFSS™ (for High Frequency Structural Simulator) was used. The following parameters were taken for the simulation.
After optimization of the loss level by adding a parallel inductance of value Lp=3.5 nH and a series capacitor of value Cs=2.7 pF in parallel on the input, the results provided in
Although the present invention has been described hereinabove with reference to specific embodiments, the present invention is not limited to the specific embodiments, and modifications will be apparent to a skilled person in the art which lie within the scope of the present invention.
For instance, while the foregoing examples have been described with respect to an open slot antenna the antenna may be provided in other shapes.
For example, the antenna may be formed by a closed slot, or by an open slot such as a tapered slot antenna or by a tapered open slot providing a Vivaldi type antenna. The conductive construction used to realise the antenna can be a plate of conductive material other than a ground reference plate or a shielding plate. The conductive feeding strip can have a meandering shape to reduce its size. Likewise, the feed strip and excitation slot can be oriented differently. They should simply cross each other to create an electromagnetic coupling enabling the supply of the antenna. Moreover, in some embodiments of the invention the radiating slot can be realised on the same plane as the excitation slot.
Many further modifications and variations will suggest themselves to those versed in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention, that being determined solely by the appended claims. In particular the different features from different embodiments may be interchanged, where appropriate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1359327 | Sep 2013 | FR | national |
