Patent Application
20160344101
The present disclosure relates to antennas of portable remote control devices.
Some portable remote control devices include antennas for wireless communications. A keyfob (“fob”) is an example of such a portable remote control device. A remote keyless entry (RKE) system includes a fob and a base station. The fob is carried by a user and the base station is at a target. The fob wirelessly communicates via its antenna with the base station to remotely control the target.
Requirements of the antenna of a portable remote control device such as a fob include providing satisfactory performance while satisfying packaging constraints.
A remote control device such as a fob includes a printed circuit board (PCB) having first and second outer sides, a first loop antenna portion on the first side of the PCB, and a second loop antenna portion on the second side of the PCB. The loop antenna portions are of different forms from one another and are connected together to form a loop antenna.
The first loop antenna portion may be in the form of a printed metallic trace on the first side of the PCB and the second loop antenna portion may be in the form of a raised metallic structure on the second side of the PCB. In this case, the first loop antenna portion is in a plane parallel with the PCB and the second loop antenna portion is in a plane perpendicular with the PCB. The first loop antenna portion forms a part of a periphery of the loop antenna and the second loop antenna portion forms a remaining part of the periphery of the loop antenna. The parts of the periphery of the loop antenna formed by the first and second loop antenna portions correspond with one another to form a fully enclosed periphery of the loop antenna.
The first loop antenna portion includes first and second ends and the second loop antenna portion includes first and second ends. The first ends of the loop antenna portions are connected together and the second ends of the loop antenna portions are connected together to form the loop antenna.
The second loop antenna portion further includes a body between the first and second ends of the second loop antenna portion. The first and second ends of the second loop antenna portion are mounted to the second side of the PCB and the body of the second loop antenna portion is raised out and away from the second side of the PCB such that an air gap is between the body of the second loop antenna portion and the second side of the PCB.
The first side of the PCB may include componentry thereon such that a surface area of the first side of the PCB is insufficient for accommodating a full loop antenna in the form of a printed metallic trace on the first side of the PCB.
The first side of the PCB may have an insufficient amount of clearance for accommodating a loop antenna portion in the form of a raised metallic structure on the first side of the PCB.
A ground layer may be placed within the PCB between the first and second sides of the PCB. The ground layer is positioned such that none of the ground layer is interposed within a loop area of the loop antenna formed by the loop antenna portions.
Another remote control device includes a first loop antenna portion in the form of a printed metallic trace on a first side of a PCB and a second loop antenna portion in the form of a raised metallic structure on a second side of the PCB. The loop antenna portions are connected together through the PCB to form a loop antenna.
Another remote control device includes a first loop antenna portion in the form of a raised metallic structure on a first side of a PCB and a second loop antenna portion in the form of a raised metallic structure on a second side of the PCB. The loop antenna portions are connected together to form a loop antenna.
A system such as a remote keyless entry (RKE) system includes a base station and a portable remote control device. The portable remote control device includes a PCB having first and second outer sides, a first loop antenna portion on the first side of the PCB, and a second loop antenna portion on the second side of the PCB. The loop antenna portions are of different forms from one another and are connected together to form a loop antenna. The portable remote control device is configured to wirelessly communicate with the base station via the loop antenna.
The portable remote control device may be configured to wirelessly communicate remote engine start and/or stop control functions with the base station via the loop antenna.
Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
Referring now to
Remote control device 12 includes an antenna 18 through which the remote control device wirelessly transmits/receives the signals to/from base station 14 to remotely control the target. Base station 14 also includes a corresponding antenna (not shown).
One example of wireless remote control system 10 is its use in a remote keyless entry (RKE) system. In a RKE system, for instance, remote control device 12 has the form of a fob to be carried by a user and target 16 is a vehicle. RKE capability enables fob 12 to remotely control various functions of the vehicle in response to user actuation of buttons or the like of the fob. As an example, base station 14 unlocks a vehicle door in response to receiving a vehicle door unlock command from fob 12. Fob 12 transmits the vehicle door unlock command to base station 14 in response to corresponding user actuation of the fob.
Other control functions of the RKE system include two-way remote engine start/stop control functions. For the two-way remote engine start control function, fob 12 transmits an engine start command in response to user actuation of the appropriate button of the fob. In turn, base station 14 starts the engine of the vehicle and transmits an engine start status update to fob 12. The user of fob 12 is made aware from the engine start status update that the engine has been started. The two-way remote engine stop control function operates the same way for stopping the engine and notifying the user of same. As described, two-way remote engine start/stop control functions involve “two-way” communications between fob 12 and base station 14 as the fob and the base station both transmit/receive signals to/from one another.
A desire is for fob 12 to have a communications range on the order of 500 meters or more for performing two-way remote engine start/stop control functions. That is, fob 12 is to be able to communicate with base station 14 for performing two-way remote engine start/stop control functions when the fob is anywhere from the base station within the communications range. Antenna 18 of fob 12 therefore should have a configuration in which the antenna provides satisfactory radiation performance (e.g., gain, directivity, etc.) and meets electrical requirements (e.g., power consumption, efficiency, FCC operating regulations, etc.) for the fob to communicate with the base station over the desired communications range.
A problem is that antenna 18 is also subject to packaging constraints. Packaging constraints call for antenna 18 fitting within a relatively small packaging space of fob 12. Packaging constraints also call for antenna 18 consuming only a limited amount of surface area of a printed circuit board (PCB) having other componentry of fob 12.
In a typical RKE system, fob 12 and base station 14 communicate signals over an Ultra-High Frequency (UHF) band. For instance, the UHF operating frequency range is between 300 MHz to 3 GHz including a 300 MHz to 1 GHz operating range and a 315 MHz operating frequency.
Antenna 18 of fob 12 is therefore electrically short due to the noted packaging constraints and the relatively long wavelength associated with the chosen UHF operating frequency. As antenna 18 is shortened to meet the packaging constraints, the efficiency and impedance of the antenna become poor and difficult to manage. Such constrained configurations can result in antenna losses due to reduced radiation efficiencies which heretofore have made it elusive for fob 12 to have the desired communications range.
A portable remote control device such as a fob in accordance with the present disclosure includes a loop antenna in a configuration in which the antenna provides satisfactory radiation performance and meets electrical requirements while satisfying the noted packaging constraints. As such, a portable remote control device according to the present disclosure is able to communicate with a base station over the desired communications range (e.g., on the order of 500 meters or more) for performing control functions such as two-way remote engine start/stop control functions.
Referring now to
The raised structure forming second loop antenna portion 28 includes first and second ends 40 and 42 with a body 44 extending therebetween. First and second ends 40 and 42 of the raised structure are mounted to bottom side 32 of PCB 22. Body 44 of the raised structure is raised out and away from bottom side 32 of PCB 22. The raised structure thereby forms a remaining part of the periphery of loop antenna 24 projected onto the plane parallel with PCB 22, as shown in
As body 44 of the raised structure is raised out and away from bottom side 32 of PCB 22, an air gap 46 is between body 44 of the raised structure and bottom side 32 of PCB 22. Any portion of body 44 of the raised structure may also be mounted to bottom side 32 of PCB 22 if desired (e.g., for enabling tuning) For instance, as shown in
First end 34 of first loop antenna portion 26 and first end 40 of second loop antenna portion 28 are electrically connected together through PCB 22 (e.g., through a via extending through the PCB). Second end 36 of first loop antenna portion 26 and second end 42 of second loop antenna portion 28 are electrically connected together through the PCB (e.g., through another via extending through the PCB). In this way, first and second loop antenna portions 26 and 28 are connected in series and thereby form loop antenna 24.
In particular, first loop antenna portion 26 forms a part of the periphery of loop antenna 24 on the plane parallel with PCB 22 (shown in
As shown in
As shown in
In a variation, the height above top side 30 of PCB 22 for accommodating componentry including loop antenna componentry is strictly limited. As a result, the available height above top side 30 of PCB 22 is simply not large enough for accommodating a loop antenna portion having the form of a raised structure. Accordingly, although a raised structure would consume minimal surface area of top side 30 of PCB 22, a printed trace is used as first loop antenna portion 26 on the top side of the PCB as the trace is essentially flat and fits within the available surface area of the top side of the PCB.
On the other hand, in this same variation, relatively more height above bottom side 32 of PCB 22 for accommodating componentry including loop antenna componentry is available. Accordingly, second loop antenna portion 28 is in the form of a raised structure as opposed to a trace. The raised structure forming second loop antenna portion 28 on bottom side 32 of PCB 22 in combination with the printed trace forming first loop antenna portion 26 on top side 30 of the PCB to form loop antenna 24 provide better antenna performance than a loop antenna formed by a pair of corresponding printed traces on respective sides of the PCB.
In another variation in which the height above top side 30 of PCB 22 for accommodating componentry including loop antenna componentry is not limited, the printed trace forming first antenna loop portion 26 may be replaced with a second raised structure.
As further shown in
As described, a portable remote control device in accordance with the present disclosure includes a loop antenna formed by a combination of first and second loop antenna portions. The first loop antenna portion is associated with one of the top and bottom sides (e.g., the top side) of a PCB and the second loop antenna portion is associated with the other one of the top and bottom sides (e.g., the bottom side) of the PCB. The first loop antenna portion is in the form of a printed metallic trace on the top side of the PCB. The second loop antenna potion is in the form of a rigid metallic structure rising out from the bottom side of the PCB. An air gap is between the body of the raised structure and the bottom side of the PCB. The PCB is designed such that no substantial ground intersects the loop and such that no ground plane is close to either loop antenna portion.
A problem addressed by the present disclosure is the ability to form a loop antenna in a highly limited space on a PCB. The loop antenna according to the present disclosure solves this problem by being formed by the combination of the first and second loop antenna portions on the respective sides of a PCB.
The loop antenna formed by the first and second loop antenna portions may be a small UHF antenna for use in long range two-way remote engine start/stop applications where the required range may be on the order of 500 meters. Despite limited available space, the loop antenna has enough loop area to achieve the required range.
In general, a loop antenna should have a certain minimum (preferably optimum) loop area to achieve a minimum required antenna gain and pattern. If the loop area is too small, then there will not be enough gain. If the loop area is too large, then it will not be possible to make at resonant as the capacitance value required to resonate the loop will be impractically small. A loop antenna in accordance with the present disclosure takes these factors into account to achieve the required range.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the present invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the present invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the present invention.
