Patent Grant
9711863
The disclosure pertains to dual band antennas for communication in wireless networks.
Wireless LAN networks (commonly known as WiFi networks) are extensively used throughout the world for providing users with access to services and/or internet connectivity through standards contained in IEEE 802.11. These standards use radio frequencies in the industrial, scientific and medical (ISM) radio bands. For most countries, the channels in these bands are located between 2.41 GHz and 2.48 GHz (denoted here as the 2.4 GHz band) or between 5.17 GHz and 5.82 GHz (denoted here as the 5 GHz band). Wireless LANs typically are based on one or both of these frequency bands, and network devices are generally required to transmit and receive in both bands, requiring dual band antennas, complicating antenna design.
The Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. The Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
Disclosed herein are representative microstrip antennas that preferentially direct radiated energy towards an end user location, have low profiles, and are conveniently implemented with other circuit elements on a PCB. The disclosed antennas do not require additional materials that tend to increase system cost or use a device chassis as a ground plane.
Disclosed herein are representative multiband antennas that can operate effectively simultaneously at two or more frequency bands. In some examples, the antennas are configured to operate on two bands such as wireless networking bands near 2.4 GHz and 5.0 GHz. Representative antennas are based on dual band microstrip or patch configurations and have directional radiation patterns that can be directed toward an anticipated location of a user mobile device or other device with which communication is intended. Such dual band antennas can provide broad frequency bandwidth based on a broadband coupling mechanism involving multiple radiators. In some examples, such antennas can be mounted on top of a device chassis and can be formed on a planar PCB that includes other device circuitry.
Dual band antennas comprise a dielectric substrate and first, second, and third conductors defined on a first surface of the dielectric substrate in an antenna area. The second and the third conductors are spaced apart from the first conductor and are capacitively coupled to the first conductor. A transmission line is in electrical contact with the first conductor and configured to communicate a radio frequency electrical signal to the first conductor. The first conductor is selected so as to correspond to about ¼ wavelength at a first frequency in a first frequency band, the second conductor is selected so as to correspond to about ½ wavelength at a frequency in a second frequency band, and the third conductor is selected to correspond to about ½ wavelength at a second frequency in the first frequency band. In some examples, the first conductor is rectangular, and a length of the first conductor corresponds to about ½ wavelength at the first frequency. In representative embodiments, an effective length of the second conductor corresponds to the half wavelength at the frequency in the second frequency band. In other examples, an effective length of the third conductor corresponds to about ½ wavelength at the second frequency in the first frequency band. In still further examples, the first frequency and the second frequency in the first frequency band are different frequencies. In some embodiments, the second conductor is a bent rectangle having an effective length that corresponds to about ¼ wavelength at the frequency in the second frequency band. In other alternatives, the substrate includes a second surface opposite the first surface, and an area of the second surface corresponding to the antenna area is substantially non-conductive.
In some examples, the first, second and third conductors are configured to preferentially radiate RF power in response to an applied RF signal away from the second surface of the substrate, and the first frequency band is at about 5-6 GHz and the second frequency band is at about 2-3 GHz.
Methods comprise coupling RF power in first and second frequency bands to a first antenna section, configured to radiate RF power in the first frequency band. The RF power in at least the first frequency band is capacitively coupled to a second antenna section configured to radiate RF power in the first frequency band. The RF power in at least the second frequency band is capacitively coupled to a third antenna section configured to radiate RF power in the second frequency band. In further examples, the RF power in at least the first frequency band is capacitively coupled to the second antenna section from the first antenna section or the RF power in at least the second frequency band is capacitively coupled to the third antenna section from the first antenna section. In typical examples, the first, second, and third antenna sections are configured as patch antenna sections and the first and second antenna sections have different peak radiation frequencies in the first frequency band. In one example, the first frequency band is at about 5-6 GHz and the second frequency band is at about 2-3 GHz. In typical examples, the first antenna section is a quarter wavelength antenna section and the second and third antenna sections are half wavelength antenna sections.
Wireless networking apparatus include a transceiver and an antenna secured to a substrate. The transceiver is configured to receive RF signals from the antenna and couple RF signals to the antenna. The antenna comprises a plurality of patch antenna sections, wherein at least one patch antenna section is capacitively coupled to a patch antenna section that is directly coupled to the transceiver. In some examples, the antenna is configured to transmit and receive radiation preferentially from a selected side of the substrate. In typical examples, at least two of the patch antenna sections are configured for wireless communication in a first frequency band, and at least one antenna section is configured to radiate in a second frequency band, wherein the first frequency band is at about 5-6 GHz and the second frequency band is at about 2-3 GHz.
The foregoing and other features and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
As used in this application and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the term “coupled” does not exclude the presence of intermediate elements between the coupled items.
The systems, apparatus, and methods described herein should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and non-obvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The disclosed systems, methods, and apparatus are not limited to any specific aspect or feature or combinations thereof, nor do the disclosed systems, methods, and apparatus require that any one or more specific advantages be present or problems be solved. Any theories of operation are to facilitate explanation, but the disclosed systems, methods, and apparatus are not limited to such theories of operation.
Although the operations of some of the disclosed methods are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed systems, methods, and apparatus can be used in conjunction with other systems, methods, and apparatus. Additionally, the description sometimes uses terms like “produce” and “provide” to describe the disclosed methods. These terms are high-level abstractions of the actual operations that are performed. The actual operations that correspond to these terms will vary depending on the particular implementation and are readily discernible by one of ordinary skill in the art.
In some examples, values, procedures, or apparatus are referred to as “lowest,” “best,” “minimum,” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, or otherwise preferable to other selections.
Some disclosed examples pertain to antennas configured for use in wireless networks based on IEEE 802.11 standards. Such networks use radiofrequencies in a first frequency band extending from 2.412 GHz to 2.484 GHz and a second frequency band extending from 5.170 GHz to 5.825 GHz. For convenience in the following description, radiofrequency electromagnetic radiation is referred to as being associated with a selected frequency and includes a frequency band about the selected frequency. Antennas are disclosed that are defined on dielectric substrates so that radiation wavelength is dependent on the radiofrequency dielectric constant of the substrate. This wavelength is shorter than a free space wavelength.
Disclosed below are representative capacitively coupled radiators, typically defined in a square or rectangular “keepout” area of a circuit substrate. Typically, a substrate area lacking a ground plane or other ground connections is referred to as a keepout area. In typical antennas, a keepout area corresponds to the antenna area, but can be larger or smaller if desired. In this way, antenna sections are distant from a ground conductor. In some examples, a transmission line is coupled to a first patch radiator configured to be a ¼ wavelength radiator in a first frequency band. Adjacent the first patch radiator (the “feed” patch) and spaced apart, L-shaped or rectangular second and third patch radiators are defined. The second patch radiator is a half wavelength radiator in the first frequency band. The third patch radiator is a half wavelength radiator in a second frequency band. The second and third patch radiators are capacitively coupled to the first patch radiator. The first and second patch radiators establish a radiation bandwidth in a first frequency band, while the third patch radiator establishes a typically narrower radiation bandwidth at a second frequency band. In some wireless network applications, the first and second frequency bands are at frequencies of about 5 GHz and 2.4 GHz. The combined patch radiators can be impedance matched to 50 ohms. Direct electrical connection via a transmission line is made to a patch radiator configured for a higher frequency rather than a lower frequency, but in other examples, direct connection is made to a lower frequency patch radiator.
For use in this description, radio frequency (RF) refers to frequencies between about 50 MHz and 10 GHz. Rectangular conductors are referred to as having a length and a width, and as used herein, a length is a longer of rectangle edge dimensions. Electromagnetic wavelength in a propagation media consisting of a certain material depends on a local dielectric constant, and wavelength refers to either free space wavelength (if vacuum material is considered) or guided or effective wavelength (if different materials are present). An effective length of a non-square conductor is a length along a center of the conductor. Effective conductor lengths can also vary due to fringing fields at conductor edges. Such fringing fields generally tend to make conductors appear electrically longer as the fringing fields extend beyond the actual conductor lengths. In some examples, rectangular antenna conductors are provided with relatively smaller area conductor sections that permit antenna tuning. Connections to antennas or antenna sections are described herein as being made with transmission lines such as striplines, slotlines, coplanar waveguides, other planar or non-planar waveguides, or coaxial cables.
Some applications of the disclosed antenna systems and methods are directed to wireless networking. The dual band nature of wireless networks typically requires the use of dual band antennas that can transmit and receive over frequency bands at about 2.5 GHz and 5 GHz. In addition, in some applications, a wireless device position relative to a user can be predicted, and directional radiation patterns may be useful. Directional antennas can provide superior RF signal strength at user locations and provide superior reception of RF signals generated by a user device. Directional antennas can permit reduced power consumption and increase battery life. Selecting a particular radiation pattern can therefore improve link power budget and reduce unwanted radiation and interference received by other devices.
Referring to
In a typical example, the substrate 108 is a PCB material. A ground conductor 113 used for circuit connections or component mounting can be provided on a second substrate surface 109 opposite the first surface 107. The ground conductor 113 does not extend into an antenna area 110 occupied by the antenna sections 102, 104, 106. If the substrate 108 is a multilayer substrate, portions between the first surface 107 and the second surface 109 in the antenna area 110 are generally free of ground plane or other conductors. In addition, the antenna area 110 preferably provides a gap 116 that is free of other conductors or components. A transmission line or waveguide 112 such as a microstrip, stripline, slotline, coplanar waveguide or other waveguide is coupled to a coaxial cable 114 and the antenna section 102.
The antenna sections 102, 104 are situated so that radiofrequency signals communicated from the waveguide 112 are capacitively coupled from the antenna section 102 to the antenna section 104 without a direct conductive path. Similarly, the antenna sections 102, 106 are situated so that radiofrequency signals communicated from the waveguide 112 are capacitively coupled from the antenna section 102 to the antenna section 106 without a direct conductive path. Accordingly, gaps 118, 120 are generally small and for antennas configured for use at wireless networking frequencies, gaps are typically less than 1.0 mm, 0.8 mm, 0.6 mm, 0.4 mm, or 0.2 mm but can be larger at lower frequencies. Additional antenna sections can be included as well, and can be situated so as to be directly or capacitively coupled to one of the antenna sections 102, 104, 106.
The antenna sections 102, 104, 106 are selected so as to receive and radiate signals in selected frequency ranges. The antenna section 102 can be selected to be responsive at a first frequency by selecting a dimension to correspond to about ½ or ¼ wavelength at the first frequency. For example, referring to an xy coordinate system 122, an x-dimension of the antenna section 102 can be about ½ or ¼ wavelength at the first frequency. As the antenna section 102 is defined on the substrate 108, the guided wavelength is dependent on the radiofrequency dielectric constant of the substrate 108 and is according shorter than free space wavelength.
Geometrical characteristics of the antenna sections 104, 106 can be similarly selected. For example, the antenna section 104 can be selected to have an x-dimension corresponding to ½ or ¼ wavelength at a second frequency. As illustrated in
In some examples, antennas are arranged to use a more compact portion of substrate surface area, and rectangular antenna areas such as shown in
Antenna conductors 210, 212, 214 are situated on the surface 202 and separated by respective gaps 211, 213, 215. A microstripline 220 extends from an area 222 of the substrate 204 to the antenna conductor 210 so as to electrically contact the antenna conductor 210. As shown in
The antenna section 210 is shown as a rectangular conductor, but other shapes can be used. An x-dimension of the antenna section 210 corresponds to a ¼ wavelength at a first frequency or in a first frequency band. As noted above, a ¼ wavelength is dependent on both frequency and the dielectric constant of the substrate. The antenna section 214 includes first and second rectangular portions 224, 225. Typically one or more dimensions of the rectangular portions are selected based on the first frequency or frequency band. The antenna portion 225 is a tuning portion that is configured to better match the effective antenna length to the first frequency or frequency band. In some examples, the antenna sections 210, 214 are selected have peak radiation efficiency at frequencies between about 5 GHz and 6 GHz, such as about 5.3 GHz and 5.6 GHz.
The antenna section 212 is an extended rectangular conductor selected to a dimension corresponding to ½ wavelength at a second frequency or frequency band. The antenna section 212 includes first and second rectangular portions 228, 229. A length of a central axis 230 of the antenna section 212 is selected to correspond to about ½ wavelength in the second frequency band. Lengths of an inner edge 232 and an outer edge 234 of the antenna section 214 can be selected to provide an intended bandwidth. These lengths tend to provide antenna radiation efficiency at frequencies at which these lengths correspond to ½ wavelength. Thus, narrower bandwidths are realized as these lengths are made closer to the length of the central axis 230.
A representative implementation of a dual band antenna for IEEE 802.11 wireless networks is illustrated in
Antenna performance of an antenna similar to that of
A representative method 600 of configuring an antenna is illustrated in
A portion of a representative wireless communication device 702 such as a router, wireless access point, game console, or media player is illustrated in
In other examples, antennas are defined on curved substrate surfaces such as cylindrical surfaces. While antennas are conveniently defined on exterior surfaces of substrates, multilayer or other substrates can be used so that antenna conductors are internal. For directional antennas, an antenna substrate can be configured to permit angular adjustment so that angles of peak antenna gain can be directed to include anticipated user or user hardware locations. For example, with a game console mounted above user eye level, a directional antenna may be tiltable.
The disclosed antennas can also be used in various other devices, such as mobile devices.
The illustrated mobile device 1000 can include a controller or processor 1010 (e.g., signal processor, microprocessor, ASIC, or other control and processing logic circuitry) for performing such tasks as signal coding, data processing, input/output processing, power control, and/or other functions. An operating system 1012 can control the allocation and usage of the components 1002 and support for one or more application programs 1014. The application programs can include common mobile computing applications (e.g., email applications, calendars, contact managers, web browsers, messaging applications), or any other computing application.
The illustrated mobile device 1000 can include memory 1020. Memory 1020 can include non-removable memory 1022 and/or removable memory 1024. The non-removable memory 1022 can include RAM, ROM, flash memory, a hard disk, or other well-known memory storage technologies. The removable memory 1024 can include flash memory or a Subscriber Identity Module (SIM) card, which is well known in GSM communication systems, or other well-known memory storage technologies, such as “smart cards.” The memory 1020 can be used for storing data and/or code for running the operating system 1012 and the applications 1014. Example data can include web pages, text, images, sound files, video data, or other data sets to be sent to and/or received from one or more network servers or other devices via one or more wired or wireless networks. The memory 1020 can be used to store a subscriber identifier, such as an International Mobile Subscriber Identity (IMSI), and an equipment identifier, such as an International Mobile Equipment Identifier (IMEI). Such identifiers can be transmitted to a network server to identify users and equipment.
The mobile device 100 can support one or more input devices 1030, such as a touchscreen 1032, microphone 1034, camera 1036, physical keyboard 1038 and/or trackball 1040 and one or more output devices 1050, such as a speaker 1052 and a display 1054. Other possible output devices (not shown) can include piezoelectric or other haptic output devices. Some devices can serve more than one input/output function. For example, touchscreen 1032 and display 1054 can be combined in a single input/output device. The input devices 1030 can include a Natural User Interface (NUI). An NUI is any interface technology that enables a user to interact with a device in a “natural” manner, free from artificial constraints imposed by input devices such as mice, keyboards, remote controls, and the like. Examples of NUI methods include those relying on speech recognition, touch and stylus recognition, gesture recognition both on screen and adjacent to the screen, air gestures, head and eye tracking, voice and speech, vision, touch, gestures, and machine intelligence. Other examples of a NUI include motion gesture detection using accelerometers/gyroscopes, facial recognition, 3D displays, head, eye, and gaze tracking, immersive augmented reality and virtual reality systems, all of which provide a more natural interface, as well as technologies for sensing brain activity using electric field sensing electrodes (EEG and related methods). Thus, in one specific example, the operating system 1012 or applications 1014 can comprise speech-recognition software as part of a voice user interface that allows a user to operate the device 1000 via voice commands. Further, the device 1000 can comprise input devices and software that allows for user interaction via a user's spatial gestures, such as detecting and interpreting gestures to provide input to a gaming application.
A wireless modem 1060 can be coupled to an antenna 1061 such as those shown above and can support two-way communications between the processor 1010 and external devices, as is well understood in the art. The modem 1060 is shown generically and can include a cellular modem for communicating with the mobile communication network 1004 and/or other radio-based modems (e.g., Bluetooth 1064 or Wi-Fi 1062). The wireless modem 1060 is typically configured for communication with one or more cellular networks, such as a GSM network for data and voice communications within a single cellular network, between cellular networks, or between the mobile device and a public switched telephone network (PSTN).
The mobile device can further include at least one input/output port 1080, a power supply 1082, a satellite navigation system receiver 1084, such as a Global Positioning System (GPS) receiver, an accelerometer 1086, and/or a physical connector 1090, which can be a USB port, IEEE 1394 (FireWire) port, and/or RS-232 port. The illustrated components 1002 are not required or all-inclusive, as any components can be deleted and other components can be added.
In view of the many possible embodiments to which the principles of the disclosed technology may be applied, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting the scope of the disclosure. We claim all that comes within the scope and spirit of the appended claims.
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