Hybrid cavity mode antenna

A communication device includes a metal chassis, a printed circuit board positioned within the metal chassis, and a hybrid cavity mode antenna. The hybrid cavity mode antenna includes a conductive wall defining at least a portion of a cavity, wherein the cavity is further defined by one or more surfaces of the metal chassis and the printed circuit board, and an electrically-fed antenna configured to radiate a first radiofrequency signal in a first frequency range. The electrically-fed antenna is electrically driven from the printed circuit board of the communication device. The electrically-fed antenna is positioned within the cavity to drive the cavity to radiate a second radiofrequency signal in a second frequency range.

BACKGROUND

Existing Wi-Fi antenna designs in communication devices require slots in the metal device enclosure or case to enable antenna functionality (e.g., to isolate the antenna from the rest of the conducting metal enclosure, to form a slot antenna). Industrial design constraints, manufacturing requirements, detuning concerns, and other issues make such slots in the metal device enclosure generally undesirable.

SUMMARY

The described technology provides a communication device including a metal chassis, a printed circuit board positioned within the metal chassis, and a hybrid cavity mode antenna. The hybrid cavity mode antenna includes a conductive wall defining at least a portion of a cavity, wherein the cavity is further defined by one or more surfaces of the metal chassis and the printed circuit board, and an electrically-fed antenna configured to radiate a first radiofrequency signal in a first frequency range. The electrically-fed antenna is electrically driven from the printed circuit board of the communication device. The electrically-fed antenna is positioned within the cavity to drive the cavity to radiate a second radiofrequency signal in a second frequency range.

DETAILED DESCRIPTIONS

An example antenna design provides a hybrid method of using a loop antenna to excite a first radiofrequency signal (e.g., at a 5 GHz antenna response) and a cavity mode antenna defined at least in part by the metal chassis of a communication device to excite a second radiofrequency signal (e.g., at a 2.5 GHz antenna response). The loop antenna is positioned within the cavity mode antenna bounds. With this antenna topology, no slots are needed in the metal chassis of the communication device to provide communications at these radiofrequency ranges, providing an industrial design look that is highly desirable and mechanical strength advantages over all previous designs.

FIG.1illustrates a communication device100including an example hybrid cavity mode antenna102having a loop antenna104and a cavity mode antenna106. The loop antenna is electrically-fed an RF signal from a transmitter of the communication device100. The example hybrid cavity mode antenna102is positioned within a metal chassis108of the communication device100and inductively and/or capacitively fed by the loop antenna104. InFIG.1, the metal chassis108defines at least a portion of a cavity110(e.g., two metal edge surfaces103and105and a back surface of the metal chassis108define at least two side walls and a back or bottom wall of the cavity110, respectively). The communication device100also includes a display112and a printed circuit board114having a ground plane. The ground plane of the printed circuit board114defines a fourth wall of the cavity110. Additional walls of the cavity110are defined by a conductive wall118, which is described in more detail with regard toFIGS.2,3, and6. In one implementation, the conductive wall118includes two grounding wall connectors120and122and a metal foam section (indicated by the dashed line connecting the two grounding wall connectors120and122), although other implementations are contemplated, including without limitation a structural metal wall extending across the metal back surface from the first metal edge surface to the second metal edge surface (seeFIG.6). In one implementation, the surfaces of the cavity110are electrically grounded.

The display112and some of its constituent components (collectively, the “display assembly”) act to substantially shield radiofrequency (RF) radiation from exiting the communication device100. In this manner, the display assembly is considered “RF opaque” with respect to RF radiation passing between the interior and exterior of the communication device100, although this term may apply to materials or components that do not block all such radiation (e.g., a material blocking substantially all or most of the RF radiation may be considered RF opaque).

Accordingly, the example hybrid cavity mode antenna102is positioned at or near a bezel region116in which the shielding material is not located. Instead, the bezel region116is considered “RF transparent” because it passes most or all of the RF radiation between the interior and exterior of the communication device100, although this term may apply to materials or components that do block some amount of such radiation (e.g., a material passing substantially all or most of the RF radiation may be considered RF transparent or even RF translucent). An opening between the printed circuit board114and the metal chassis108presents a radiating slot in the cavity110from which a radiofrequency signal can radiate. The radiating slot is positioned to overlap or predominantly overlap the bezel region116. As such, the described implementation can operate as a cavity-backed slot antenna. The loop antenna104is positioned within the cavity, operating at approximately 5 GHz and driving the cavity and the radiating slot at approximately 2.4 GHz.

As shown in the expanded view117, the example hybrid cavity mode antenna102is positioned near the edge of the communication device100, with the loop antenna104positioned in the bezel region116so that RF radiation may pass between the interior and exterior of the communication device100through the RF transparent bezel region116. The loop antenna104is also positioned within the cavity110to excite the cavity mode of the cavity110. It should be noted that the cavity110is also positioned at or near the bezel region116to radiate through the RF transparent materials of the bezel region116.

A second hybrid cavity mode antenna152is also shown between the metal edge surface105and another metal edge surface150. Additional hybrid cavity mode antennas may be employed in the same communication device100. In addition, the locations of such hybrid cavity mode antennas may also vary from those illustrated implementations. For example, a hybrid cavity mode antenna may be positioned against the side of the metal chassis, rather than in the corner of the metal chassis.

FIG.2illustrates a perspective view of an example hybrid cavity mode antenna200in a communication device202. All or most of the components of the communication device202are contained within a metal chassis204. The bounds of a cavity of the hybrid cavity mode antenna200are defined in two dimensions by the conductive wall203(including the grounding connectors210and212), a first metal edge surface220of the metal chassis204, and a second metal edge surface222of the metal chassis204. The bottom surface of the cavity is defined by the back metal surface of the metal chassis204, and the top surface of the cavity is defined by the ground plane of the printed circuit board (PCB206). An opening between the PCB206and the first metal edge surface220or the second metal edge surface222defines a radiating slot252in the cavity. One or more electrically-fed antennas are positioned within the cavity. InFIG.2, a loop antenna208is electrically driven by a feed from the PCB206to radiate with a first radiofrequency range (e.g., encompassing 5 GHz) and is positioned within the cavity to inductively couple (and/or capacitively couple) into the cavity mode of the resulting cavity mode antenna at a second radiofrequency range (e.g., encompassing 2.5 GHz). A second loop antenna254is also shown to the left of the cavity. Example electrically-fed antennas may include without limitation loop antennas and monopole antennas.

InFIG.2, the conductive wall203defines a portion of a cavity surface under the PCB206. The conductive wall203can include one or more grounding wall connectors (see grounding wall connectors210and212) that electrically connect the ground plane of the PCB206and the conductive wall203to the metal chassis204of the communication device202. The dimensions of the cavity, as substantially defined by the metal chassis204, the ground plane of the PCB206, the conductive wall define the volume of the cavity and therefore contribute to the second radiofrequency range in which the cavity radiates.

A cavity-driving antenna may capacitively and/or inductively coupled with the cavity to drive the cavity to radiate. Various implementations may include multiple cavity-driving antennas. For example, in one implementation, two loop antennas are positioned within the cavity on opposing sides of the cavity. In other examples, one or more monopole antennas may be used to drive the cavity. In addition, multiple hybrid cavity mode antennas may be implemented in a single communication device.

In some implementations, the conductive wall203can also include tuning circuitry250, such as one or more inductive and/or capacitive elements, any of which may be variable or switchable in order to dynamically adjust the tuning of the cavity antenna. It should also be understood that another electrically-conductive material may be used in place of metal for the chassis, foam, and other components. One or more tuning circuits may be employed at various locations on the cavity walls.

FIG.3illustrates a top view and three cross-sectional views of an example hybrid cavity mode antenna300. The example hybrid cavity mode antenna300in a communication device includes a loop antenna302and a cavity antenna, the dimensions of which are defined by the cavity304. The loop antenna302and at least a portion of the cavity304are positioned at or near the bezel region303of communication device between the display315(covered by a cover glass317) and the side walls306and/or308of a metal chassis of the communication device. In one implementation, the loop antenna302radiates at a radiofrequency signal in a first radiofrequency range (e.g., 5 GHz).

In this top plan view ofFIG.3, the dimensions of the cavity304are defined by the side walls306and308of the metal chassis of the communication device, the back wall310of the metal chassis, two grounding wall connectors312and314, and the ground plane of a printed circuit board316. A conductive wall318connects the two grounding wall connectors312and314, the back wall310of the metal chassis, and the ground plane of the printed circuit board316. In one implementation, the conductive wall318is formed from a metal foam, which is both structural and rigid, although other conductive wall structures are contemplated, including without limitation one or more metal or otherwise conductive plates soldered to the printed circuit board316and the chassis surfaces. In one implementation, the loop antenna302is positioned within the cavity304and inductivity couples with the cavity304to radiate the cavity304(as a cavity antenna) at a radiofrequency signal in a second radiofrequency range (e.g., 2.5 GHz). The grounding wall connectors312and314can also be made of a metal foam, one or more conductive plates, etc.

FIG.4illustrates characteristics400of an example hybrid cavity mode antenna. Lines402and404represent antenna impedances of two different loop antennas, each positioned within the cavity mode antenna, respectively. The line402represents the return loss of a loop antenna positioned to the left of the cavity when the cavity is viewed as shown in the plan view ofFIG.3. The line404represents the return loss of a loop antenna positioned to the right of the cavity when the cavity is viewed as shown in the plan view ofFIG.3(e.g., where the loop antenna302is shown inFIG.3). The line406represents the isolation between the two antennas, where the lower the isolation, the more efficient the two antennas operate.

FIG.5illustrates an example communication device500for implementing the features and operations of the described technology. The communication device500may be a client device, such as a laptop, mobile device, desktop, tablet; a server/cloud device; an internet-of-things device; an electronic accessory; or another electronic device. The communication device500includes one or more processor(s)502and a memory504. The memory504generally includes both volatile memory (e.g., RAM) and non-volatile memory (e.g., flash memory). An operating system510resides in the memory504and is executed by the processor(s)502.

In an example communication device500, as shown inFIG.5, one or more modules or segments, such as communication software550, application modules, and other modules, are loaded into the operating system510on the memory504and/or storage520and executed by processor(s)502. The storage520may store communication parameters and other data and be local to the communication device500or may be remote and communicatively connected to the communication device500.

The communication device500includes a power supply516, which is powered by one or more batteries or other power sources and which provides power to other components of the communication device500. The power supply516may also be connected to an external power source that overrides or recharges the built-in batteries or other power sources.

The communication device500may include one or more communication transceivers530which may be connected to one or more antenna(s)532to provide network connectivity (e.g., mobile phone network, Wi-Fi®, Bluetooth®) to one or more other servers and/or client devices (e.g., mobile devices, desktop computers, or laptop computers). The communication device500may further include a network adapter536, which is a type of communication device. The communication device500may use the adapter and any other types of communication devices for establishing connections over a wide-area network (WAN) or local-area network (LAN). It should be appreciated that the network connections shown are exemplary and that other communication devices and means for establishing a communications link between the communication device500and other devices may be used.

The communication device500may include one or more input devices534such that a user may enter commands and information (e.g., a keyboard or mouse). These and other input devices may be coupled to the server by one or more interfaces538, such as a serial port interface, parallel port, or universal serial bus (USB). The communication device500may further include a display522, such as a touch screen display.

FIG.6illustrates an example implementation of a hybrid cavity mode antenna in a communication device600. All or most of the components of the communication device600are contained within a metal chassis (or an otherwise electrically conductive chassis). A conductive wall604is shown connecting a first edge surface606of the metal chassis to a second edge surface608of the metal chassis, forming a cavity within the area610. The cavity is also bounded (above and below) by the bottom surface612of the metal chassis and a printed circuit board (not shown) of the communication device600. Such boundaries form a cavity volume. InFIG.6, the conductive wall604is constructed from metal plates, but one or more portions of the conductive wall604may be formed from metal foam or other conductive materials.

In the illustrated implementation, the cavity is bounded by a first side614of the conductive wall604of approximately 40 mm and a second side616of the conductive wall604of approximately 86 mm. The opening between the metal chassis and the printed circuit board presents a slot in the cavity from which a radiofrequency signal can radiate. As such, the described implementation can operate as a cavity-backed slot antenna. A feed antenna (such as a loop antenna or a monopole antenna) would be positioned within the cavity, operating at approximately 5 GHz and driving the cavity and the radiating slot at approximately 2.5 GHz.

Cavity dimensions and supported frequencies can vary in different implementations. In one implementation, 2.4 GHz corresponds to a cavity mode in this design as 15000 millimeters3, and 5.2 GHz corresponds to a cavity mode in this design as 3990 millimeters3, although other volumes, dimensions, and frequency band may be employed.

An example communication device (100) includes a metal chassis (108), a printed circuit board (114) positioned within the metal chassis, and a hybrid cavity mode antenna (102). The hybrid mode antenna includes a conductive wall (118) defining at least a portion of a cavity (110), wherein the cavity is further defined by one or more surfaces of the metal chassis and the printed circuit board. The hybrid cavity mode antenna also includes an electrically-fed antenna (104) configured to radiate a first radiofrequency signal in a first frequency range, wherein the electrically-fed antenna is electrically driven from the printed circuit board of the communication device, the electrically-fed antenna being positioned within the cavity to drive the cavity to radiate a second radiofrequency signal in a second frequency range.

Another example communication device of any preceding device is provided, wherein the metal chassis includes a metal back surface (310) and at least a first metal edge surface (606) and a second metal edge surface (608), the cavity being defined by the metal back surface, the first metal edge surface, the second metal edge surface, the printed circuit board, and the conductive wall.

Another example communication device of any preceding device is provided, wherein the conductive wall includes a tuning circuit (250) connecting the conductive wall to at least one of the first metal edge surface and the second metal edge surface.

Another example communication device of any preceding device is provided, wherein the communication device includes a display (112) and a bezel region (116) between the display and the first metal edge surface, and the cavity includes a radiating slot (252) positioned in the bezel region.

Another example communication device of any preceding device is provided, wherein the conductive wall includes at least one grounding wall connector (212) electrically connected to the first metal edge surface.

Another example communication device of any preceding device is provided, wherein the metal chassis includes a metal back surface, and the conductive wall is positioned between the printed circuit board and the metal back surface.

Another example communication device of any preceding device is provided, wherein the metal chassis includes a metal back surface and at least a first metal edge surface and a second metal edge surface, the conductive wall extending across the metal back surface from the first metal edge surface to the second metal edge surface.

Another example communication device of any preceding device is provided, wherein the conductive wall electrically connects the metal back surface, the first metal edge surface, and the second metal edge surface.

Another example communication device of any preceding device is provided, wherein the electrically-fed antenna is a first electrically-fed antenna, and further including a second electrically-fed antenna (254) configured to radiate a third radiofrequency signal in the first frequency range, wherein the second electrically-fed antenna is electrically driven from the printed circuit board of the communication device, the second electrically-fed antenna being positioned within the cavity to drive the cavity to radiate the second radiofrequency signal in the second frequency range.

Another example communication device of any preceding device is provided, wherein the second electrically-fed antenna is a loop antenna.

Another example communication device of any preceding device is provided, wherein the second electrically-fed antenna is a monopole antenna.

Another example communication device of any preceding device is provided, wherein the first electrically-fed antenna is positioned at one side of the cavity and the second electrically-fed antenna is positioned at an opposing side of the cavity.

Another example communication device of any preceding device is provided, wherein the first electrically-fed antenna is a loop antenna.

Another example communication device of any preceding device is provided, wherein the conductive wall includes a metal foam.

Another example communication device of any preceding device is provided, wherein the metal chassis includes a metal back surface and at least a first metal edge surface, a second metal edge surface, and a third metal edge surface (150), the hybrid cavity mode antenna is a first hybrid cavity mode antenna with the conductive wall extending across the metal back surface from the first metal edge surface to the second metal edge surface, and the communication device further includes a second hybrid cavity mode antenna (152) including a second conductive wall extending across the metal back surface from the first metal edge surface to the third metal edge surface.

An example hybrid cavity mode antenna (102) includes an electrically-conductive chassis (108) for a communication device (100), the electrically-conductive chassis having an electrically-conductive back surface (310), a first electrically-conductive edge surface (606), and a second electrically-conductive edge surface (608). The example hybrid cavity mode antenna further includes a conductive wall (118) defining at least a portion of a cavity (110), wherein the cavity is further defined by the electrically-conductive back surface, the first electrically-conductive edge surface, and the second electrically-conductive edge surface of the electrically-conductive chassis, and an electrically-fed antenna (104) configured to radiate a first radiofrequency signal in a first frequency range, wherein the electrically-fed antenna is positioned within the cavity to drive the cavity to radiate a second radiofrequency signal in a second frequency range.

Another example hybrid cavity mode antenna of any preceding antenna is provided, wherein the electrically-fed antenna is a loop antenna.

Another example hybrid cavity mode antenna of any preceding antenna is provided, wherein the conductive wall electrically contacts the electrically-conductive back surface, the first electrically-conductive edge surface, and the second electrically-conductive edge surface.

Another example hybrid cavity mode antenna of any preceding antenna is provided, wherein the conductive wall includes at least one grounding wall connector (212) electrically connected to the first electrically-conductive edge surface.

Another example hybrid cavity mode antenna of any preceding antenna is provided, wherein the conductive wall includes an electrically-conductive foam.

A number of implementations of the described technology have been described. Nevertheless, it will be understood that various modifications can be made without departing from the spirit and scope of the recited claims.