Slot antenna for a network card

Techniques to integrate a slot antenna with a wireless network card for use with a wireless communication network.

BACKGROUND

Wireless networks are becoming increasingly prevalent due to the convenience provided to a user. For example, a physical location such as a home or office may include a number of computers, such as a personal computer, laptop computer, handheld computer, and so forth. Such devices are traditionally connected to a network using wired communications media, such as twisted-pair wire or co-axial cable. Wireless networks, however, are currently available that eliminate the need for such wired communications media. An example of a wireless network may comprise an 802.11 network as defined by the Institute of Electrical and Electronics Engineers (IEEE). To arrange a computer for operation with a wireless network, however, may require the use of an antenna. The antenna is typically separate from the PC, thereby introducing additional cables, connectors and space requirements. Consequently, there may be a need for improvements in antenna design for a wireless network.

DESCRIPTION OF SPECIFIC EMBODIMENTS

FIG. 1illustrates a block diagram of a system100. System100may comprise, for example, a communication system to communicate information between multiple nodes. The nodes may comprise any physical or logical entity having a unique address in system100. The unique address may comprise, for example, a network address such as an Internet Protocol (IP) address, device address such as a Media Access Control (MAC) address, and so forth. The embodiments are not limited in this context.

The nodes may be connected by one or more types of communications media. The communications media may comprise any media capable of carrying information signals, such as metal leads, semiconductor material, twisted-pair wire, co-axial cable, fiber optics, radio frequency (RF) spectrum, and so forth. The connection may comprise, for example, a physical connection or logical connection.

The nodes may be connected to the communications media by one or more input/output (I/O) adapters. The I/O adapters may be configured to operate with any suitable technique for controlling communication signals between computer or network devices using a desired set of communications protocols, services and operating procedures. The I/O adapter may also include the appropriate physical connectors to connect the I/O adapter with a given communications medium. Examples of suitable1/O adapters may include a network interface card (NIC), radio/air interface, and so forth.

The general architecture of system100may be implemented as a wireless communication system. When implemented as a wireless system, one or more nodes shown in system100may further comprise additional components and interfaces suitable for communicating information signals over the designated RF spectrum. For example, a node of system100may include an omni-directional antenna, a wireless RF radio or transmitter/receiver (“transceiver”), control logic, and so forth. The embodiments are not limited in this context.

The nodes of system100may be configured to communicate different types of information, such as media information and control information. Media information may refer to any data representing content meant for a user, such as voice information, video information, audio information, text information, alphanumeric symbols, graphics, images, and so forth. Control information may refer to any data representing commands, instructions or control words meant for an automated system. For example, control information may be used to route media information through a system, or instruct a node to process the media information in a predetermined manner.

The nodes may communicate the media and control information in accordance with one or more protocols. A protocol may comprise a set of predefined rules or instructions to control how the nodes communicate information between each other. The protocol may be defined by one or more protocol standards, such as the standards promulgated by the Internet Engineering Task Force (IETF), International Telecommunications Union (ITU), IEEE, a company such as Intel® Corporation, and so forth. An example of a protocol suitable for use with system100may include a protocol from the IEEE 802.11 family of protocols. The embodiments, however, are not limited in this context.

Referring again toFIG. 1, system100may comprise a node102and a node104. In one embodiment, for example, nodes102and104may comprise wireless nodes arranged to communicate information over a wireless communication medium, such as RF spectrum. Wireless nodes102and104may represent a number of different wireless devices, such as mobile or cellular telephone, a computer equipped with a wireless access card or modem, a handheld client device such as a wireless personal digital assistant (PDA), a wireless access point (WAP), a base station, a mobile subscriber center, a radio network controller, and so forth. In one embodiment, for example, node102may represent a computer such as a PC, laptop computer, handheld computer, and so forth. Node104may represent a wireless access point (WAP). Both nodes102and104may be arranged to communicate media information and control information in accordance with an 802.11 protocol. Node104may be further connected to a high-speed network via a DSL modem, cable modem, optional router, and so forth. AlthoughFIG. 1shows a limited number of nodes, it can be appreciated that any number of nodes may be used in system100.

In one embodiment, wireless nodes102and104may each include a processing system having a processor and memory. For example, wireless node102may include a processor106and memory110, and wireless node104may include a processor108and memory112. Examples for processors106and108may include a general-purpose processor such as made by Intel (Corporation, or a dedicated processor such as a digital signal processor (DSP), network processor, embedded processor, micro-controller, controller and so forth. Examples for memory110and112may include any machine-readable media, such as read-only memory (ROM), random-access memory (RAM), synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), flash memory, magnetic disk (e.g., floppy disk and hard drive), optical disk (e.g., CD-ROM), and so forth. The embodiments are not limited in this context.

In one embodiment, node102may need a wireless network card to operate with an 802.11 network. As discussed previously, node102may comprise a desktop PC, for example. A desktop PC may be arranged with multiple expansion slots connected by an I/O bus. Each expansion slot may be arranged to receive a network card having suitable physical and electrical interfaces to communicate with the rest of node102, such as processor106and memory110. In one embodiment, for example, the expansion slots and network card may both conform to the Peripheral Component Interface (PCI) family of standards as defined by the PCI Special Interest Group (SIG), such as the PCI SIG Specification Version 3.0, dated Apr. 19, 2004 (collectively referred to as the “PCI Specification”). One problem associated with conventional wireless network cards, however, is that they typically use an external antenna. The external antenna may comprise a device separate from, and external to, the housing or chassis for node102. This may introduce the need for additional cables, connectors and space requirements. By way of contrast, node102may be configured with a wireless network card with an integrated slot antenna. The use of an integrated slot antenna may reduce or eliminate the need for additional cables and connectors, and may also eliminate the additional space consumed by any external antenna. A wireless network card with integrated slot antenna may be described in more detail with reference toFIGS. 2–5.

FIG. 2illustrates a diagram of a wireless network card200. Wireless network card200may comprise a radio such as transceiver202connected to an RF transmission line206via a trace204. Transceiver202may be integrated with a printed circuit board (PCB)210, or may comprise a separate device attached to PCB210. RF transmission line206may comprise, for example, a microstrip transmission line operating at 50 Ohms. In one embodiment, RF transmission line206may be arranged to encircle a fastening hole208. Fastening hole208may be used to attach an antenna probe to PCB210using a fastening device, such as a screw, nail, rivet, and so forth. An antenna probe suitable for use with wireless network card200may be described with reference toFIGS. 3A and 3B.

FIG. 3Aillustrates a top and bottom view for an antenna probe300. Antenna probe300may comprise an antenna probe to attach to PCB210. As shown inFIG. 3A, antenna probe300may have a shape of a hollow cylinder. Antenna probe300may include a fastening hole304to correspond in size and shape to fastening hole208of PCB210. The bottom surface of antenna probe300may comprise a coupling section306to correspond in size and shape to RF transmission line206. Coupling section306should be in substantial contact with RF transmission line206when antenna probe300is mounted to PCB210to facilitate coupling of energy communicated by transceiver202through RF transmission line206via trace204.

FIG. 3Billustrates a perspective view for antenna probe300. As shown inFIG. 3B, fastening hole304of antenna probe300may further comprise an inner side308and an outer side310. Fastening hole304may be arranged to operate with a fastening device as described with reference toFIG. 2. For example, inner side308of fastening hole304may have threads for a screw to securely fasten antenna probe300with PCB210. The embodiments are not limited in this context.

In one embodiment, wireless network card200and antenna probe300may be combined with a director structure to form a wireless network card with an integrated slot antenna. A director structure may be described in more detail with reference toFIGS. 4A–C.

FIG. 4Aillustrates a perspective view for a director structure in accordance with one embodiment.FIG. 4Aillustrates a director structure400. Director structure400may have an approximately rectangular shape with four sides404,406,408and410.FIG. 4Aillustrates a first and second sides406and408, respectively. A third side404may be hidden from view inFIG. 4A, but is shown in detail inFIG. 4B. A fourth side410may be formed as an integral part of director structure400, or alternatively, a portion of fourth side410may be formed by a surface of PCB210when director structure400is attached to PCB210. In one embodiment, the four sides may form a waveguide core402. Waveguide core402may be used to guide an electromagnetic wave for the excitation of a slot in side404of director structure400.

FIG. 4Billustrates a first side view for a director structure in accordance with one embodiment.FIG. 4Billustrates a view of side404for director structure400. As shown inFIG. 4B, director structure400may comprise a reverse C structure having an antenna probe notch412formed into one side. Antenna probe notch412may have a shape and size to receive outer side310of antenna probe300. When assembled, antenna probe300may be inserted through antenna probe notch412to position antenna probe300within waveguide core402.

FIG. 4Cillustrates a second side view of a director structure in accordance with one embodiment.FIG. 4Cillustrates a view of side410for director structure400.FIG. 4Cprovides another view of antenna probe notch412. Although antenna probe notch412is shown inFIGS. 4B and 4Cas a rectangular notch formed entirely through side410, it may be appreciated that antenna probe notch412may be formed in other shapes in accordance with a given implementation. For example, antenna probe notch412may be formed as a circle, square, triangle, ellipse, or any other shape to accommodate antenna probe300. The particular size and shape of antenna probe notch412may be dependent upon various waveguide characteristics desired for a given implementation of an integrated slot antenna.

In one embodiment, antenna probe300and director structure400may be combined to form a slot antenna for use with a transceiver, such as transceiver202. The slot antenna may be fastened to, or integrated with, wireless network card200. A wireless network card with an integrated slot antenna may be described in more detail with reference toFIGS. 5A–E.

FIG. 5Aillustrates a side view of a device500comprising a wireless network card with a slot antenna in accordance with one embodiment. As shown inFIG. 5A, device500may include a slot antenna502mounted to PCB210having RF transmission line206. Slot antenna502may comprise, for example, director structure400mounted to PCB210via one or more fastening devices504. PCB210may include transceiver202, with an optional transceiver shield514to cover transceiver202. PCB210may further include an external antenna connector516for use with a conventional external antenna.

FIG. 5Billustrates a front view in direction B of device500in accordance with one embodiment. As shown inFIG. 5B, director structure400may comprise a rectangular structure to form a slot414having antenna probe notch412. Director structure400may couple to PCB210by either attaching director structure400to PCB210, or forming director structure400as an integral part of a PCI bracket506that fits on first end510of PCB210. PCI bracket506maybe used to connect device500to the housing or chassis of node102, for example. The embodiments are not limited in this context.

FIG. 5Cillustrates a bottom view in direction C of device500in accordance with one embodiment. As shown inFIG. 5C, antenna probe400may be connected to PCB210using a fastening device508. Examples for fastening device508may include a screw, nail, rivet and so forth. Fastening device508may be inserted through fastening hole208of PCB210and into fastening hole304of antenna probe400. Antenna probe400may be appropriately positioned within director structure400through antenna probe notch412.

FIG. 5Dillustrates a back view in direction D of device500in accordance with one embodiment.FIG. 5Dillustrates side408of director structure400, as well as fastening devices406used to mount director structure400to PCB210.

FIG. 5Eillustrates a perspective view of device500in accordance with one embodiment.FIG. 5Eillustrates sides406and408of director structure400. As shown inFIG. 5E, director structure400may be open on each end, thereby exposing waveguide core402to the surrounding environment.

In operation, device500may operate as a wireless network card having an integral slot antenna to send and receive electromagnetic waves for transceiver202. In one embodiment, for example, antenna probe412may receive electromagnetic signals from RF transmission line206, and radiate electromagnetic waves within director structure400. Director structure400may operate as a waveguide for the electromagnetic waves, with slot414to emit a portion of the electromagnetic waves.

In one embodiment, slot antenna502may be tuned to an operating frequency of approximately 2.4 Gigahertz. Further, slot antenna502may have an input impedance of approximately 50 ohms. Slot antenna502may be positioned within director structure400through antenna probe notch412. In this manner, director structure400may help partially isolate antenna probe412from interference generated by PCB210.

In one embodiment, device500may comprise an 802.11 wireless network card having a first end510and a second end512. Device500maybe inserted into a housing for node102, with the housing having a card slot to expose first end510, with slot antenna402to be connected to first end510. The position of slot antenna502may be arranged such that slot414may emit a portion of the electromagnetic waves radiated by antenna probe412outside of the housing for node102. In this manner, slot antenna502may propagate the electromagnetic waves to node104, and receiver electromagnetic waves transmitted by node104.

In summary, some embodiments may be directed to a folded slot antenna integrated with a low profile PCI bracket. The antenna is formed from a slot cut in the PCI bracket, and an antenna probe which is mounted directly onto the PCI radio card, and couples energy from the PCI card radio to the slot. A director structure is used to isolate the antenna probe and slot antenna from the PCI card, and potentially interfering signals. The whole antenna structure is designed to be a highly efficient antenna across the 2.4 GHz band. The input impedance of the antenna structure is designed to be 50 Ohms, which may be implemented by top loading capacitance between the top of the antenna probe and the director structure. The antenna probe may be fed by a 50 Ohm RF microstrip transmission line. The antenna probe may be mounted on the RF microstrip transmission line in such a way as to transfer the RF energy from a “Pseudo TEM” propagation mode to an open probe structure.

The embodiments may provide several advantages. For example, some embodiments may provide a highly efficient internal antenna for the rear location of a desk top PC. By way of contrast, conventional designs use an external antenna such as an elbow antenna, or a low profile antenna mounted directly on the chassis itself. Such designs may require additional connectors and/or cabling. Further, such designs may require open space on the PC chassis itself, or space behind the chassis for an elbow antenna. As form factors for computers continue to reduce in size, a node such as a PC may continue having little or no space at the back of the chassis for any kind of antenna. Some embodiments, however, may be arranged so that they have little or no impact on the PC Chassis at all. Further, some embodiments may include a PCI bracket antenna design that provides a significant cost reduction over existing antenna solutions. The antenna slot and director structure may comprise an extended bracket folded with a inexpensive tool. The antenna probe may comprise a rod of metal with a threaded hole at one end. Since the slot antenna is integrated with the wireless network card, it may replace a much higher cost procured antenna. As a result, the PCI bracket antenna may lead to a significant reduction and cost and complexity for wireless network solutions.

All or portions of an embodiment may be implemented using an architecture that may vary in accordance with any number of factors, such as desired computational rate, power levels, heat tolerances, processing cycle budget, input data rates, output data rates, memory resources, data bus speeds and other performance constraints. For example, an embodiment may be implemented using software executed by a processor. In another example, an embodiment may be implemented as dedicated hardware, such as a circuit, an application specific integrated circuit (ASIC), Programmable Logic Device (PLD) or digital signal processor (DSP), and so forth. In yet another example, an embodiment may be implemented by any combination of programmed general-purpose computer components and custom hardware components. The embodiments are not limited in this context.