Patent Publication Number: US-9853684-B2

Title: High radiation efficiency antenna systems

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 62/061,745 filed Oct. 9, 2014. All sections of the aforementioned application(s) are incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The subject disclosure relates to high radiation efficiency antenna systems. 
     BACKGROUND 
     Modern wireless communication devices often utilize wide band antennas which are intended to cover a range of frequencies such as from 700 to 2700 MHz. Antenna design is made more challenging by handset requirements that include long battery life, more frequency bands, larger display screens with reduced borders, and thinner form factors. 
     Cellular communication devices such as cellular telephones, tablets, and laptops can support multi-cellular access technologies, peer-to-peer access technologies, personal area network access technologies, and location receiver access technologies, which can operate concurrently. Cellular communication devices have also integrated a variety of consumer features such as MP3 players, color displays, gaming applications, cameras, and other features. Cellular communication devices can be required to communicate at a variety of frequencies, and in some instances are subjected to a variety of physical and functional use conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIGS. 1A-1F  depict an illustrative embodiment of a communication device that provides high radiation efficiency antennas in conjunction with impedance tuning; 
         FIGS. 1G-1P  depict graphical representations of the efficiency and correlation coefficients for the antennas of  FIGS. 1A-F ; 
         FIG. 1Q  depicts an illustrative embodiment of another communication device that provides high radiation efficiency antennas in conjunction with impedance tuning; 
         FIG. 1R  depicts an illustrative embodiment of ground clearance for another communication device that provides high radiation efficiency antennas in conjunction with impedance tuning; 
         FIG. 1S  depicts a graphical representation of ground clearance and screen area ratio for communication devices; 
         FIG. 2  depicts an illustrative embodiment of a portion of a transceiver of the communication device of  FIGS. 1A-1F ; 
         FIGS. 3-6  depict illustrative embodiments of a tunable matching network of the transceiver of  FIG. 2 ; 
         FIG. 7  depicts an illustrative embodiment of a look-up table utilized by the communication device of  FIG. 1A-1F  for controlling tunable reactive elements utilized by the communication device; 
         FIGS. 8-11  depict illustrative physical and operational use cases of a communication device; 
         FIG. 12  depicts an exemplary method associated with the embodiments of  FIGS. 1-11 ; and 
         FIG. 13  depicts an illustrative diagrammatic representation of a machine in the form of a computer system within which a set of instructions, when executed, may cause the machine to perform any one or more of the methodologies disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     The subject disclosure describes, among other things, illustrative embodiments of devices that utilize high radiation efficiency in conjunction with tunable RF matching technology to correct antenna mismatch loss. One or more of the embodiments, include a high efficiency antenna system including a primary and diversity antenna pair that utilizes dynamic antenna tuning for one or both of the antennas. The primary and diversity antennas can work together with tunable impedance matching circuits at low ground clearances such as for MIMO applications that retain high efficiencies. These antennas can have high radiation efficiency so that the tunable impedance matching circuits can realize high antenna efficiency over wide frequency bands. In one embodiment utilizing voltage variable tuning, these antennas can cover a wide frequency range such as of 700 to 960 (LB), 1700 to 2200 MHz (MB) and 2300-2700 MHz (HB). In one embodiment, both antennas have a LB dominated flag, and a MB-HB dominated flag. In another embodiment, the location of the two antennas can be selected to achieve low correlation coefficient necessary for increased or optimum MIMO operation. 
     The exemplary embodiments improve antenna efficiency and radiation efficiency. Antenna efficiency is essentially the ratio (e.g., in % or dB) of total power radiating out of the antenna divided by total power injected into the antenna. Radiation efficiency is the ratio of “calculated total power radiated out of the antenna if no power was lost due to mismatch”, divided by total power injected into the antenna. The latter, radiation efficiency, can be a better measure of the antenna&#39;s ability to radiate, and a better measure of how much power is lost as dissipative energy, either in the ohmc losses in the antenna/phone device, or if in use case, into the user. 
     Other configurations or elements can be used in place of or in addition to one or more elements or configurations of the exemplary embodiments, including configurations and/or elements described in U.S. Provisional Application No. 62/061,750 entitled “Wide Band Antenna Systems” which was filed on Oct. 9, 2014, as well as described in U.S. patent application Ser. No. 14/877,979 entitled “Wide Band Antenna Systems” which was filed contemporaneously herewith, the disclosures of which are incorporated herein by reference in their entirety. 
     In one or more embodiments, the primary and diversity antennas can include parallel coupled monopoles for LB and for MB and HB communications. In another embodiment, the antennas can be set on or in proximity to the bottom (or the top) of the wireless devices (e.g., a mobile phone). In one or more embodiments, single feed antennas can be utilized. In one or more embodiments, high antenna efficiency and high radiation efficiency for tunable matching applications can be provided. In one or more embodiments, a small dimension in the y direction can be utilized, which is suitable for a small ground clearance device which enables larger screens and/or larger batteries without making the device overall dimensions larger. 
     In one or more embodiments, low ground clearance can be utilized. In one or more embodiments, good antenna performance can be provided, such as in Beside Head and Hand Right (BHHR) for primary and in Beside Head and Hand Left (BHHL) for diversity. In one or more embodiments, low antenna pattern correlation coefficients can be provided. 
     One or more of the exemplary embodiments can be utilized in multi-antenna and/or multi-port antenna systems used to address Carrier Aggregation (CA) requirements for handsets, such as LB antennas that must cover 700-960 MHz under all use-cases. 
     Other embodiments are described by the subject disclosure. 
     One embodiment of the subject disclosure includes a mobile communication device including a transceiver, an antenna system, a matching network and a controller. The antenna system is coupled with the transceiver, where the antenna system includes a first pair of flag antennas and a second pair of flag antennas, where one of the first or second pairs of flag antennas are primary antennas and the other of the first or second pairs of flag antennas are diversity antennas, where the first pair of flag antennas have a first single feed point and are connected via a first transmission line, and where the second pair of flag antennas have a second single feed point and are connected via a second transmission line. The matching network is coupled with the transceiver and the antenna system, where the matching network comprises a tunable reactive element. The controller is coupled with the matching network, where the controller adjusts the tunable reactive element to provide impedance tuning. 
     One embodiment of the subject disclosure includes an antenna system having first and second pairs of flag antennas and an RF switch. The first pair of flag antennas has a first single feed point and is connected with a transceiver of a mobile communication device. The second pair of flag antennas has a second single feed point and is connected with the transceiver of the mobile communication device. An RF switch connected with the first and second pairs of flag antennas, where the RF switch has a first position in which the first pair of flag antennas are primary antennas and the second pair of flag antennas are diversity antennas. The RF switch has a second position in which the second pair of flag antennas are the primary antennas and the first pair of flag antennas are the diversity antennas. 
     One embodiment of the subject disclosure includes a communication device having a transceiver, an antenna system, a matching network and a controller. The antenna system is coupled with the transceiver, where the antenna system includes a first pair of antennas and a second pair of antennas. One of the first or second pairs of antennas are primary antennas and the other of the first or second pairs of antennas are diversity antennas. The first pair of antennas has a first single feed point and are connected via a first transmission line. The second pair of antennas has a second single feed point and are connected via a second transmission line. The matching network is coupled with the transceiver and the antenna system, where the matching network comprises a tunable reactive element. The controller is coupled with the matching network, where the controller adjusts the tunable reactive element to provide impedance tuning. 
       FIG. 1A  depicts an illustrative embodiment of a communication device  100 . The communication device  100  can comprise one or more transceivers  102  coupled to an antenna system  101 , which can be any number of antennas. As an example, each transceiver can have transmitter and receiver sections herein described as transceiver  102  or transceivers  102 . The communication device  100  can have one or more tunable circuits  122  including reactive element(s)  190 , one or more tuning sensors  124 , a user interface (UI)  104 , a power supply  114 , a location receiver  116 , a motion sensor  118 , an orientation sensor  120 , and/or a controller  106  for managing operations thereof. The transceiver  102  can support short-range and/or long-range wireless access technologies, including Bluetooth, ZigBee, Wireless Fidelity (WiFi), Digital Enhance Cordless Telecommunications (DECT), or cellular communication technologies, just to mention a few. The communication device  100  can be a multimode device capable of providing communication services via various wireless access technologies, including two or more such services simultaneously. 
     Cellular technologies can include, for example, Global System for Mobile (GSM), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Universal Mobile Telecommunications (UMTS), World interoperability for Microwave (WiMAX), Software Defined Radio (SDR), Long Term Evolution (LTE), as well as other next generation wireless communication technologies as they arise. The transceiver  102  can also be adapted to support circuit-switched wireline access technologies such as Public Switched Telephone Network (PSTN), packet-switched wireline access technologies such as TCP/IP, Voice over IP-VoIP, etc., or combinations thereof. 
     Referring additionally to  FIG. 1B , the schematic structure is illustrated of primary and diversity antennas  101 A and  101 B of antenna system  101 . Each antenna  101 A and  101 B can include two flags (e.g., an MB/HB flag  150  and a LB flag  155 ) that are attached to a single feed. A high impedance transmission line  160  can extend the frequency of operation lower for the antenna. The low band flag  155  can have a controlled coupling to the mid and high band flag  150  that extends the frequency of operation higher for the antenna system  101 . In one or more embodiments, the symmetry (including being substantially symmetrical such as having similar shapes with dimensions that are within 10% of each other) of the primary and diversity antennas of antenna system  101  can control the correlation coefficient so that their antenna patterns spatially complement each other. 
     In one or more embodiments, dimensions, shapes and/or positions for the group of antennas of antenna system  101  can achieve a desired performance characteristic while fitting different mechanical arrangements. These dimensions, shapes and/or positions can be adjusted to achieve other desired performance characteristic and/or for fitting other mechanical arrangements. In  FIGS. 1C-1D , L 1 =Length of Mid &amp; High Band flag on Primary Antenna; L 2 =Length of Low Band flag on Primary Antenna; W 1 =Width of Mid &amp; High Band flag on Primary Antenna; W 2 =Width of Low Band flag on Primary Antenna; L 3 =Length of Mid &amp; High Band flag on Diversity Antenna; L 4 =Length of Low Band flag on Diversity Antenna; W 3 =Width of Mid &amp; High Band flag on Diversity Antenna; W 4 =Width of Low Band flag on Diversity Antenna; G 1 =Width of Gap between two flags on Primary Antenna; G 2 =Width of Gap between two flags on Diversity Antenna; T 1 =Length of transmission line on Primary Antenna; and T 2 =Length of transmission line on Diversity Antenna. As an example shown in  FIGS. 1C-1D , the following values can be utilized for a plastic chassis containing a 66.5 mm×127.7 mm ground plane with 8 mm ground clearance: L 1 =26.4 mm (Feed can be 17 mm down the flag length); L 2 =30.8 mm (Flag can curve around corner); W 1 =3.2 mm; W 2 =5 mm; L 3 =24.5 mm (Feed can be 18 mm down the flag length); L 4 =30 mm (Flag can curve around corner); W 3 =2.5 mm; W 4 =5 mm; G 1 =1.5 mm; G 2 =1.5 mm; T 1 =21 mm (0.8 mm wide); T 2 =24 mm (0.8 mm wide); distance between Primary and Diversity antenna=14.8 mm. In one or more embodiments, these lengths can be adjusted approximately +/−10%. In one or more embodiments, these gaps can be adjusted approximately +/−1 mm. In one or more embodiments, the flag widths can be adjusted approximately +/−1 mm. 
     Referring additionally to  FIGS. 1E-1F , the first and second pairs of flag antennas  101 A and  101 B are shown where each of the high band flags are wrapped around the edge of the antenna carrier. The first and second pairs of flag antennas  101 A and  101 B can be positioned in the bottom of the communication device  100 . 
     Referring to  FIG. 1G , a graphical representation is presented for the measured free space low bands antenna (solid) and radiation (dashed) efficiency of the primary (black) and diversity (red) antennas at 8 mm ground clearance. 
     Referring to  FIG. 1H , a graphical representation is presented for the measured free space mid and high bands antenna (solid) and radiation (dashed) efficiency of the primary (black) and diversity (red) antennas at 8 mm ground clearance. 
     Referring to  FIG. 1I , a graphical representation is presented for the measured LB primary antenna efficiency (solid) and radiation efficiency (dashed) tested in the BHHR (black) and BHHL (red) conditions. 
     Referring to  FIG. 1J , a graphical representation is presented for the measured LB diversity antenna efficiency (solid) and radiation efficiency (dashed) tested in the BHHR (black) and BHHL (red) conditions. 
     Referring to  FIG. 1K , a graphical representation is presented for the measured MB and HB primary antenna efficiency (solid) and radiation efficiency (dashed) tested in the BHHR (black) and BHHL (red) conditions. 
     Referring to  FIG. 1L , a graphical representation is presented for the measured MB and HB diversity antenna efficiency (solid) and radiation efficiency (dashed) tested in the BHHR (black) and BHHL (red) conditions. 
     Referring to  FIG. 1M , a graphical representation is presented for the measured LB antenna pattern correlation coefficients. 
     Referring to  FIG. 1N , a graphical representation is presented for the measured MB &amp; HB antenna pattern correlation coefficients. 
     Referring to  FIG. 1O , a graphical representation is presented for the expected peak (red) and measured (blue) low band antenna efficiency using high radiation efficiency antennas and with a tunable impedance matching network at a selected sample of tuner voltages. 
     Referring to  FIG. 1P , a graphical representation is presented for the expected peak (red) and measured (blue) mid and high antenna efficiency using high radiation efficiency antennas and a tunable impedance matching network at a selected sample of tuner voltages. 
     Referring to  FIG. 1Q , an exemplary antenna voltage variable impedance matching tuner circuit schematic is superimposed on a board layout. 
     Referring to  FIG. 1R , an illustrative embodiment of ground clearance is illustrated for another communication device that provides high radiation efficiency antennas in conjunction with impedance tuning; 
     Referring to  FIG. 1S , a graphical representation is illustrated for ground clearance and screen area ratio for communication devices; 
     In one embodiment, the communication device  100  can include an RF switch  150  (or other component) for switching the functionality of antennas of the antenna system  101  including switching primary antennas to diversity antennas and vice versa. For example, parameters of the communication device  100  can be monitored, detected or otherwise determined in order to identify a change in impedance. The impedance change can result from a change in use case (e.g., switching from left hand to right hand to hold phone). The identification of the impedance change can trigger a change in the antenna system configuration via the RF switch  150  (e.g., controlled by controller  106 ) such that the first pair of flag antennas  101 A that were previously operating as the primary antennas now operate as the diversity antennas and the second pair of flag antennas  101 B that were previously operating as the diversity antennas now operate as the primary antennas. The number of times this switch occurs can be based on the detected parameters, such as according to a user that keeps switching hands during a communication session. 
     The tunable circuit  122  can comprise one or more variable reactive elements such as variable capacitors, variable inductors, or combinations thereof that are tunable with digital and/or analog bias signals. The tunable circuit  122  can represent a tunable matching network coupled to the antenna system  101  to compensate for a change in impedance of the antenna  101 , a compensation circuit to compensate for mutual coupling in a multi-antenna system, an amplifier tuning circuit to control operations of an amplifier of the transceiver  102 , a filter tuning circuit to alter a pass band of a filter used by the transceiver  102 , and so on. In one or more embodiments, the tunable circuit  122  is connected with all of the flag antennas of antenna system  101  to enable tuning of all of the antennas. 
     In one or more embodiments, tuning sensors  124  can be placed at any stage of the transceiver  102  such as, for example, before or after a matching network  202 , and/or at a power amplifier  201  as shown in  FIG. 2 . The tuning sensors  124  can utilize any suitable sensing technology such as directional couplers, voltage dividers, or other sensing technologies to measure signals at any stage of the transceiver  102 . The digital samples of the measured signals can be provided to the controller  106  by way of analog-to-digital converters included in the tuning sensors  124 . Data provided to the controller  106  by the tuning sensors  124  can be used to measure, for example, transmit power, transmitter efficiency, receiver sensitivity, power consumption of the communication device  100 , frequency band selectivity by adjusting filter passbands, linearity and efficiency of power amplifiers, specific absorption rate (SAR) requirements, and so on. The controller  106  can be configured to execute one or more tuning algorithms to determine desired tuning states of the tunable circuit  122  based on the foregoing measurements. The controller  106  can also switch the primary and diversity antennas via RF switch  150  based on data obtained from the tuning sensors  124 . 
     The UI  104  can include a depressible or touch-sensitive keypad  108  with a navigation mechanism such as a roller ball, a joystick, a mouse, or a navigation disk for manipulating operations of the communication device  100 . The keypad  108  can be an integral part of a housing assembly of the communication device  100  or an independent device operably coupled thereto by a tethered wireline interface (such as a USB cable) or a wireless interface supporting, for example, Bluetooth. The keypad  108  can represent a numeric keypad commonly used by phones, and/or a QWERTY keypad with alphanumeric keys. The UI  104  can further include a display  110  such as monochrome or color LCD (Liquid Crystal Display), OLED (Organic Light Emitting Diode) or other suitable display technology for conveying images to an end user of the communication device  100 . In an embodiment where the display  110  is touch-sensitive, a portion or all of the keypad  108  can be presented by way of the display  110  with navigation features. 
     The display  110  can use touch screen technology to also serve as a user interface for detecting user input. As a touch screen display, the communication device  100  can be adapted to present a user interface with graphical user interface (GUI) elements that can be selected by a user with a touch of a finger. The touch screen display  110  can be equipped with capacitive, resistive or other forms of sensing technology to detect how much surface area of a user&#39;s finger has been placed on a portion of the touch screen display. This sensing information can be used to control the manipulation of the GUI elements or other functions of the user interface. The display  110  can be an integral part of the housing assembly of the communication device  100  or an independent device communicatively coupled thereto by a tethered wireline interface (such as a cable) or a wireless interface. 
     The UI  104  can also include an audio system  112  that utilizes audio technology for conveying low volume audio (such as audio heard in proximity of a human ear) and high volume audio (such as speakerphone for hands free operation). The audio system  112  can further include a microphone for receiving audible signals of an end user. The audio system  112  can also be used for voice recognition applications. The UI  104  can further include an image sensor  113  such as a charged coupled device (CCD) camera for capturing still or moving images. 
     The power supply  114  can utilize common power management technologies such as replaceable and rechargeable batteries, supply regulation technologies, and/or charging system technologies for supplying energy to the components of the communication device  100  to facilitate long-range or short-range portable applications. Alternatively, or in combination, the charging system can utilize external power sources such as DC power supplied over a physical interface such as a USB port or other suitable tethering technologies. 
     The location receiver  116  can utilize location technology such as a global positioning system (GPS) receiver capable of assisted GPS for identifying a location of the communication device  100  based on signals generated by a constellation of GPS satellites, which can be used for facilitating location services such as navigation. The motion sensor  118  can utilize motion sensing technology such as an accelerometer, a gyroscope, or other suitable motion sensing technology to detect motion of the communication device  100  in three-dimensional space. The orientation sensor  120  can utilize orientation sensing technology such as a magnetometer to detect the orientation of the communication device  100  (north, south, west, and east, as well as combined orientations in degrees, minutes, or other suitable orientation metrics). 
     The communication device  100  can use the transceiver  102  to also determine a proximity to or distance to cellular, WiFi, Bluetooth, or other wireless access points by sensing techniques such as utilizing a received signal strength indicator (RSSI) and/or signal time of arrival (TOA) or time of flight (TOF) measurements. 
     The controller  106  can utilize computing technologies such as a microprocessor, a digital signal processor (DSP), programmable gate arrays, application specific integrated circuits, and/or a video processor with associated storage memory such as Flash, ROM, RAM, SRAM, DRAM or other storage technologies for executing computer instructions, controlling, and processing data supplied by the aforementioned components of the communication device  100 . 
     Other components not shown in  FIG. 1  can be used by the subject disclosure. The communication device  100  can include a slot for inserting or removing an identity module such as a Subscriber Identity Module (SIM) card. SIM cards can be used for identifying and registering for subscriber services, executing computer programs, storing subscriber data, and so forth. 
     One or more of the exemplary embodiments take into account that mobile device antennas can perform more efficiently when placed in areas away from chassis metal. One or more of the exemplary embodiments can include a large screen. One or more of the exemplary embodiments can utilize thinner form factors that proportionately utilize more of chassis metal for mechanical strength. One or more of the exemplary embodiments can provide low antenna pattern correlation coefficients between the primary and diversity antennas so that the antenna pair has more robust MIMO coverage. One or more of the exemplary embodiments can provide antenna performance that meets all carrier specifications, not only in free space, but also in wide ranging use cases, especially in use cases of the left hand head (BHHL) and the right hand head (BHHR). One or more of the exemplary embodiments can provide for a grounded connector, such as a micro USB connector, for charging and wired data transfer, placed at the bottom center edge of the phone. One or more of the exemplary embodiments can enable one or more speakers to be positioned on or in proximity to the bottom of the phone. 
       FIG. 2  depicts an illustrative embodiment of a portion of the wireless transceiver  102  of the communication device  100  of  FIG. 1 . In GSM applications, the transmit and receive portions of the transceiver  102  can include amplifiers  201 ,  203  coupled to a tunable matching network  202  that is in turn coupled to an impedance load  206 . In one or more embodiments, a full duplex configuration without switch  204  can be utilized such as for an LTE or WCDMA application. The tunable matching network  202  can include all or a portion of the tuning circuit  122  of  FIG. 1 , such as variable capacitors to enable high linearity tuning while satisfying performance criteria such as insertion loss thresholds and/or response time speed. The impedance load  206  in the present illustration can be all or a portion of the antenna system (e.g., reconfigurable via RF switch  150 ) as shown in  FIG. 1A  (herein antenna  206 ). In one or more embodiments, the RF switch  150  can be on the Tx/Rx side of the matching network(s)  202 . In another embodiment, a separate matching network  202  can be used for each antenna. A transmit signal in the form of a radio frequency (RF) signal (TX) can be directed to the amplifier  201  which amplifies the signal and directs the amplified signal to the antenna  206  by way of the tunable matching network  202  when switch  204  is enabled for a transmission session. The receive portion of the transceiver  102  can utilize a pre-amplifier  203  which amplifies signals received from the antenna  206  by way of the tunable matching network  202  when switch  204  is enabled for a receive session. Other configurations of  FIG. 2  are possible for other types of cellular access technologies such as CDMA, UMTS, LTE, and so forth. The exemplary embodiments are applicable to all types of radio technologies including WiFi, GPS and so forth, and are not intended to be limited to cellular access technologies. These undisclosed configurations are applicable to the subject disclosure. 
       FIGS. 3-4  depict illustrative embodiments of the tunable matching network  202  of the transceiver  102  of  FIG. 2 . In one embodiment, the tunable matching network  202  can comprise a control circuit  302  and a tunable reactive element  310 . The control circuit  302  can comprise a DC-to-DC converter  304 , one or more digital to analog converters (DACs)  306  and one or more corresponding buffers  308  to amplify the voltage generated by each DAC. The amplified signal can be fed to one or more tunable reactive components  404 ,  406  and  408  such as shown in  FIG. 4 , which depicts a possible circuit configuration for the tunable reactive element  310 . In this illustration, the tunable reactive element  310  includes three tunable capacitors  404 - 408  and two inductors  402 - 403  with a fixed inductance. Circuit configurations such as “Tee”, “Pi”, and “L” configurations for a matching circuit are also suitable configurations that can be used in the subject disclosure. 
     The tunable capacitors  404 - 408  can each utilize technology that enables tunability of the reactance of the component. One embodiment of the tunable capacitors  404 - 408  can utilize voltage or current tunable dielectric materials. The tunable dielectric materials can utilize, among other things, a composition of barium strontium titanate (BST). In another embodiment, the tunable reactive element  310  can utilize semiconductor varactors, or micro-electromechanical systems (MEMS) technology capable of mechanically varying the dielectric constant of a capacitor. Other present or next generation methods or material compositions that result in a voltage or current tunable reactive element are applicable to the subject disclosure for use by the tunable reactive element  310  of  FIG. 3 . 
     The DC-to-DC converter  304  can receive a DC signal such as 3 volts from the power supply  114  of the communication device  100  in  FIG. 1A . The DC-to-DC converter  304  can use technology to amplify a DC signal to a higher range (e.g., 30 volts) such as shown. The controller  106  can supply digital signals to each of the DACs  306  by way of a control bus  307  of “n” or more wires or traces to individually control the capacitance of tunable capacitors  404 - 408 , thereby varying the collective reactive impedance of the tunable matching network  202 . The control bus  307  can be implemented with a two-wire serial bus technology such as a Serial Peripheral Interface (SPI) bus (referred to herein as SPI bus  307 ). With an SPI bus  307 , the controller  106  can transmit serialized digital signals to configure each DAC in  FIG. 3 . The control circuit  302  of  FIG. 3  can utilize digital state machine logic to implement the SPI bus  307 , which can direct digital signals supplied by the controller  106  to the DACs to control the analog output of each DAC, which is then amplified by buffers  308 . In one embodiment, the control circuit  302  can be a stand-alone component coupled to the tunable reactive element  310 . In another embodiment, the control circuit  302  can be integrated in whole or in part with another device such as the controller  106 . 
     Although the tunable reactive element  310  is shown in a unidirectional fashion with an RF input and RF output, the RF signal direction is illustrative and can be interchanged. Additionally, either port of the tunable reactive element  310  can be connected to a feed point of the antenna  206 , a structural element of the antenna  206  in an on-antenna configuration, or between antennas for compensating mutual coupling when diversity antennas are used, or when antennas of differing wireless access technologies are physically in close proximity to each other and thereby are susceptible to mutual coupling. The tunable reactive element  310  can also be connected to other circuit components of a transmitter or a receiver section such as filters, amplifiers, and so on, to control operations thereof. 
     In another embodiment, the tunable matching network  202  of  FIG. 2  can comprise a control circuit  502  in the form of a decoder and a tunable reactive element  504  comprising switchable reactive elements such as shown in  FIG. 6 . In this embodiment, the controller  106  can supply the control circuit  502  signals via the SPI bus  307 , which can be decoded with Boolean or state machine logic to individually enable or disable the switching elements  602 . The switching elements  602  can be implemented with semiconductor switches, MEMS, or other suitable switching technology. By independently enabling and disabling the reactive elements  604  (capacitor or inductor) of  FIG. 6  with the switching elements  602 , the collective reactive impedance of the tunable reactive element  504  can be varied by the controller  106 . 
     The tunable reactive elements  310  and  504  of  FIGS. 3 and 5 , respectively, can be used with various circuit components of the transceiver  102  to enable the controller  106  to manage performance factors such as, for example, but not limited to, transmit power, transmitter efficiency, receiver sensitivity, power consumption of the communication device  100 , frequency band selectivity by adjusting filter passbands, linearity and efficiency of power amplifiers, SAR requirements, among other operational parameters. 
       FIG. 7  depicts an illustration of a look-up table stored in memory, which can be indexed by the controller  106  of the communication device  100  of  FIG. 1A  according to physical and/or functional use cases of the communication device  100 . The desired tuning state can include values for the biasing signals and/or capacitance values to be employed for tuning of the variable capacitors, such as variable capacitors  425 . A physical use case can represent a physical state of the communication device  100 , while a functional use case can represent an operational state of the communication device  100 . For example, for a flip phone  800  of  FIG. 8 , an open flip can represent one physical use case, while a closed flip can represent another physical use case. In a closed flip state (i.e., bottom and top flips  802 - 804  are aligned), a user is likely to have his/her hands surrounding the top flip  804  and the bottom flip  802  while holding the phone  800 , which can result in one range of load impedances experienced by an internal or retrievable antenna (not shown) of the phone  800 . The range of load impedances of the internal or retrievable antenna can be determined by empirical analysis. 
     With the flip open a user is likely to hold the bottom flip  802  with one hand while positioning the top flip  804  near the user&#39;s ear when an audio system of the phone  800 , such audio system  112  of  FIG. 1 , is set to low volume, and voice channel is active. If, on the other hand, the audio system  112  is in speakerphone mode, it is likely that the user is positioning the top flip  804  away from the user&#39;s ear. In these arrangements, different ranges of load impedances can be experienced by the internal or retrievable antenna, which can be analyzed empirically. The low and high volume states of the audio system  112 , as well as, a determination that a voice channel is active, illustrates varying functional use cases. 
     For a phone  900  with a slideable keypad  902  (illustrated in  FIG. 9 ), the keypad in an outward position can present one range of load impedances of an internal antenna, while the keypad in a hidden position can present another range of load impedances, each of which can be analyzed empirically. For a smartphone  1000  (illustrated in  FIG. 10 ) presenting a video game, an assumption can be made that the user is likely to hold the phone away from the user&#39;s ear in order to view the game. Placing the smartphone  1000  in a portrait position  1002  can represent one physical and operational use case, while utilizing the smartphone  1000  in a landscape position  1004  presents another physical and operational use case. 
     The number of hands and fingers used in the portrait mode may be determined by the particular type of game being played by the user. For example, a particular video game may require a user interface where a single finger in portrait mode may be sufficient for controlling the game. In this scenario, it may be assumed that the user is holding the smartphone  1000  in one hand in portrait mode and using a finger with the other. By empirical analysis, a possible range of impedances of the internal antenna(s) of the communication device can be determined when using the video game in portrait mode. Similarly, if the video game selected has a user interface that is known to require two hands in landscape mode, another estimated range of impedances of the internal antenna can be determined empirically. 
     A multimode phone  1100  capable of facilitating multiple access technologies such as GSM, CDMA, LTE, WiFi, GPS, and/or Bluetooth in two or more combinations can provide additional insight into possible ranges of impedances experienced by two or more internal antennas of the multimode phone  1100 . For example, a multimode phone  1100  that provides GPS services by processing signals received from a constellation of satellites  1102 ,  1104  can be empirically analyzed when other access technologies are also in use. Suppose, for instance, that while navigation services are enabled, the multimode phone  1100  is facilitating voice communications by exchanging wireless messages with a cellular base station  1106 . In this state, an internal antenna of the GPS receiver may be affected by a use case of a user holding the multimode phone  1100  (e.g., near the user&#39;s ear or away from the user&#39;s ear). The effect on the GPS receiver antenna and the GSM antenna by the user&#39;s hand position can be empirically analyzed. 
     Suppose in another scenario that the antenna of a GSM transceiver is in close proximity to the antenna of a WiFi transceiver. Further assume that the GSM frequency band used to facilitate voice communications is near the operational frequency of the WiFi transceiver. Also assume that a use case for voice communications may result in certain physical states of the multimode phone  1100  (e.g., slider out), which can result in a probable hand position of the user of the multimode phone  1100 . Such a physical and functional use case can affect the impedance range of the antenna of the WiFi transceiver as well as the antenna of the GSM transceiver. 
     A close proximity between the WiFi and GSM antennas and the near operational frequency of the antennas may also result in cross-coupling between the antennas. Mutual or cross-coupling under these circumstances can be measured empirically. Similarly, empirical measurements of the impedances of other internal antennas can be measured for particular physical and functional use configurations when utilizing Bluetooth, WiFi, Zigbee, or other access technologies in peer-to-peer communications with another communication device  1108  or with a wireless access point  1110 . In diversity designs such as multiple-input and multiple output (MIMO) antennas, physical and functional use cases of a communication device can be measured empirically to determine how best to configure a tunable compensation circuit  122  such as shown in  FIG. 1A . 
     The number of physical and functional use cases of a communication device  100  can be substantial when accounting for combinations of access technologies, frequency bands, antennas of different access technologies, antennas configured for diversity designs, and so on. These combinations, however, can be empirically analyzed to determine load impedances of the antenna(s), mutual coupling between them, and the effects on transmitter and receiver performance metrics. Mitigation strategies to reduce mutual coupling, counter the effect of varying load impedances, and to improve other performance metrics of the transceiver  102  can also be determined empirically. The empirical data collected and corresponding mitigation strategies can be recorded in the look-up table of  FIG. 7  and indexed according to combinations of physical and functional use cases detected by the communication device  100 . The information stored in the look-up table can be used in open-loop RF tuning applications to initialize tunable circuit components of the transceiver  102 , as well as, tuning algorithms that control operational aspects of the tunable circuit components. 
     In one or more embodiments, information in table  7  can be used for impedance tuning in conjunction with re-configuring or switching the primary and diversity antennas. 
       FIG. 12  depicts an illustrative method  1200  for providing a high linearity tuning device or component, such as tuning circuit  122 . Method  1200  can begin with step  1202  in which one or more device parameters can be identified, measured or otherwise determined. The parameters can be various types that are utilized for determining or otherwise predicting an impedance mismatch including forward and reverse power metrics and so forth. At  1204 , impedance tuning can be performed according to the device parameters. The impedance tuning can be based on closed-loop feedback or can be based on open-loop feedback. For instance, tuning can be performed by sampling parameters and then consulting a look-up table (e.g., table  700 ) that is indexed by the parameters. In another embodiment, the look-up table can be utilized for initial tuning (for example coarse tuning) and then subsequent tuning (for example fine tuning) can be performed based on an algorithm without utilizing the look-up table. 
     At  1206 , if the tuning results in an impedance mismatch within a defined threshold for performance then method  1200  can return to  1202  and continue monitoring device parameters. If the threshold is not satisfied then at  1208  the RF switch  150  can be utilized to switch the primary and diversity antennas. 
     Other embodiments can be applied to the subject disclosure without departing from the scope of the claims described below. 
     It should be understood that devices described in the exemplary embodiments can be in communication with each other via various wireless and/or wired methodologies. The methodologies can be links that are described as coupled, connected and so forth, which can include unidirectional and/or bidirectional communication over wireless paths and/or wired paths that utilize one or more of various protocols or methodologies, where the coupling and/or connection can be direct (e.g., no intervening processing device) and/or indirect (e.g., an intermediary processing device such as a router). 
     Radio band information can be generally available or otherwise retrievable in communication devices, which provides the broadest definition of where in a frequency spectrum a communication device such as a handset is operating (e.g., transmitting). In communication systems (e.g., cellular systems), frequencies can be commonly allocated for usage in a block or range of frequencies. This block or range of frequencies is commonly known as a radio band. Multiple radio bands can be present in any given cellular system, and in any geographic location there can be multiple cellular systems present. 
     A radio channel can identify a discrete set of frequencies in a cellular system that contains the downlink (from base station to the handset) and uplink (from handset to base station) radio signals. Downlink is also referred to as Rx and uplink is also referred to as Tx. In most systems, such as WCDMA (Wideband Code Division Multiple Access), uplink and downlink can use separate frequencies that are separated by the duplex distance, which is the number of Hz separating the uplink and downlink paths. For other systems, such as TD-LTE (Time Division Long Term Evolution), the uplink and downlink can use the same frequency. 
     One or more of the exemplary embodiments can utilize radio band information, including only radio band information in some embodiments or radio band information in combination with other information (e.g., measured operational parameters), for antenna tuning. The exemplary embodiments can apply to various types of devices, including wireless handsets operating utilizing one or more of various communication protocols. 
     RF tuning based on limited information, such as only the radio band, can create a number of problems. In an ideal cellular system that employs RF tuning, the tuner would be set to match every frequency on which the radio receives or transmits, with the understanding that typically a single antenna is used for both Rx and Tx which requires the RF tuner to change tuning state as the RF signal on the antenna changes frequency. For half-duplex systems, such as GSM that would be for every Rx and Tx, including neighbor cells. In full-duplex systems, such as WCDMA where both Rx and Tx are present concurrently, the RF tuner has to change when the frequency changes for handoffs and neighbor cell monitoring, and additionally the tuning state has to be a duplex setting for Rx and Tx on a frequency between the Rx and Tx frequencies. 
     In order to perform RF tuning in such an ideal system, the entity controlling the tuner could require exact knowledge in real time of all relevant information pertaining to operating the tuner, such as the radio timing, radio band, radio channel, RF duplex information, and transmit state. Tuning based on limited information occurs when the entity controlling the tuner does not have all the information required to set the RF tuner to match an exact frequency at a given time. For example, real time channel information could be missing, in which case the tuner control entity could set the RF tuner based on information pertaining to the Radio Band only. 
     Transmit (Tx) and Receive (Rx) operations often cannot or are not tuned in real-time. This can result in or necessitate a broader duplex type tuning. Duplex tuning refers to where the tunable element for a particular sub-band or radio channel is tuned to a frequency between uplink and downlink; one tuning state can be used for both Rx and Tx in this case. In some systems that are full-duplex (concurrent uplink and downlink, such as WCDMA), duplex tuning is commonly used. Other systems that are half-duplex (uplink and downlink are not concurrent, such as GSM), the tuner can be tuned for both Rx and Tx. 
     Sub-band describes a grouping of frequencies (e.g., radio channels) consisting of one or more radio channels. In tuning applications, sub-dividing a radio band into multiple sub-bands can provide the advantage of being able to apply a particular tuning state to a small or smaller range of radio channels. Sub-bands can be used in conjunction with storage and application of calibration data in cellular handsets, providing a compromise between accuracy and amount of storage needed to hold said calibration data. 
     An example of a radio band is the GSM 900 band, in which the uplink frequencies can occupy the range 880.0 to 915.0 MHz and the downlink frequencies can occupy the range 925.0 to 960.0 MHz. The duplex spacing can be 45 MHz. The first channel can be channel 975 which has uplink at 880.2 MHz and downlink at 915.2 MHz. The last channel can be channel 124 which has uplink at 914.8 MHz and downlink at 959.8 MHz. 
     The GSM 900 band can, for example, be subdivided into 3 sub bands as follows: Sub band 1 ranging from channel 975 to channel 1023 (48 channels, 9.6 MHz wide), Sub Band 2 ranging from channel 0 to channel 66 (66 channels, 13.2 MHz wide), and sub band 3 ranging from channel 67 to channel 124 (57 channels, 11.4 MHz wide). This is an example of a radio band and sub-bands, and the present disclosure can include various configurations of radio bands and sub-bands. 
     Similar principles can be applied to other existing wireless access technologies (e.g., UMTS, etc.) as well as future generation access technologies. 
     The exemplary embodiments describe use of pairs of flag antennas. However, one or more of the exemplary embodiments can utilize other types of antennas that are paired together where one of the pairs may or may not be a flag antenna. 
     The use of the term single feed point can include a configuration where there is no more than one feed point connected with a circuit. 
       FIG. 13  depicts an exemplary diagrammatic representation of a machine in the form of a computer system  1300  within which a set of instructions, when executed, may cause the machine to perform any one or more of the methods discussed above. One or more instances of the machine can operate, for example, as the communication device  100  of  FIG. 1A , the controller  106 , the control circuit  302 , and/or the decoder  502 , for enabling high linearity tuning via one or more of multiple bias points, anti-parallel diodes, choke inductor(s) and/or ground inductors. In some embodiments, the machine may be connected (e.g., using a network  1326 ) to other machines. In a networked deployment, the machine may operate in the capacity of a server or a client user machine in server-client user network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. 
     The machine may comprise a server computer, a client user computer, a personal computer (PC), a tablet PC, a smart phone, a laptop computer, a desktop computer, a control system, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. It will be understood that a communication device of the subject disclosure includes broadly any electronic device that provides voice, video or data communication. Further, while a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methods discussed herein. 
     The computer system  1300  may include a processor (or controller)  1302  (e.g., a central processing unit (CPU), a graphics processing unit (GPU, or both), a main memory  1304  and a static memory  1306 , which communicate with each other via a bus  1308 . The computer system  1300  may further include a display unit  1310  (e.g., a liquid crystal display (LCD), a flat panel, or a solid state display. The computer system  1300  may include an input device  1312  (e.g., a keyboard), a cursor control device  1314  (e.g., a mouse), a disk drive unit  1316 , a signal generation device  1318  (e.g., a speaker or remote control) and a network interface device  1320 . In distributed environments, the embodiments described in the subject disclosure can be adapted to utilize multiple display units  1310  controlled by two or more computer systems  1300 . In this configuration, presentations described by the subject disclosure may in part be shown in a first of the display units  1310 , while the remaining portion is presented in a second of the display units  1310 . 
     The disk drive unit  1316  may include a tangible computer-readable storage medium  1322  on which is stored one or more sets of instructions (e.g., software  1324 ) embodying any one or more of the methods or functions described herein, including those methods illustrated above. The instructions  1324  may also reside, completely or at least partially, within the main memory  1304 , the static memory  1306 , and/or within the processor  1302  during execution thereof by the computer system  1300 . The main memory  1304  and the processor  1302  also may constitute tangible computer-readable storage media. 
     Dedicated hardware implementations including, but not limited to, application specific integrated circuits, programmable logic arrays and other hardware devices can likewise be constructed to implement the methods described herein. Applications that may include the apparatus and systems of various embodiments broadly include a variety of electronic and computer systems. Some embodiments implement functions in two or more specific interconnected hardware modules or devices with related control and data signals communicated between and through the modules, or as portions of an application-specific integrated circuit. Thus, the example system is applicable to software, firmware, and hardware implementations. 
     In accordance with various embodiments of the subject disclosure, the methods described herein are intended for operation as software programs running on a computer processor. Furthermore, software implementations can include, but not limited to, distributed processing or component/object distributed processing, parallel processing, or virtual machine processing can also be constructed to implement the methods described herein. 
     While the tangible computer-readable storage medium  1322  is shown in an example embodiment to be a single medium, the term “tangible computer-readable storage medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term “tangible computer-readable storage medium” shall also be taken to include any non-transitory medium that is capable of storing or encoding a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methods of the subject disclosure. 
     The term “tangible computer-readable storage medium” shall accordingly be taken to include, but not be limited to: solid-state memories such as a memory card or other package that houses one or more read-only (non-volatile) memories, random access memories, or other re-writable (volatile) memories, a magneto-optical or optical medium such as a disk or tape, or other tangible media which can be used to store information. Accordingly, the disclosure is considered to include any one or more of a tangible computer-readable storage medium, as listed herein and including art-recognized equivalents and successor media, in which the software implementations herein are stored. 
     Although the present specification describes components and functions implemented in the embodiments with reference to particular standards and protocols, the disclosure is not limited to such standards and protocols. Each of the standards for Internet and other packet switched network transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP) represent examples of the state of the art. Such standards are from time-to-time superseded by faster or more efficient equivalents having essentially the same functions. Wireless standards for device detection (e.g., RFID), short-range communications (e.g., Bluetooth, WiFi, Zigbee), and long-range communications (e.g., WiMAX, GSM, CDMA, LTE) are contemplated for use by computer system  1300 . 
     The illustrations of embodiments described herein are intended to provide a general understanding of the structure of various embodiments, and they are not intended to serve as a complete description of all the elements and features of apparatus and systems that might make use of the structures described herein. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Figures are also merely representational and may not be drawn to scale. Certain proportions thereof may be exaggerated, while others may be minimized. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. 
     Although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, can be used in the subject disclosure. In one or more embodiments, features that are positively recited can also be excluded from the embodiment with or without replacement by another component or step. The steps or functions described with respect to the exemplary processes or methods can be performed in any order. The steps or functions described with respect to the exemplary processes or methods can be performed alone or in combination with other steps or functions (from other embodiments or from other steps that have not been described). Less than all of the steps or functions described with respect to the exemplary processes or methods can also be performed in one or more of the exemplary embodiments. Further, the use of numerical terms to describe a device, component, step or function, such as first, second, third, and so forth, is not intended to describe an order or function unless expressly stated so. The use of the terms first, second, third and so forth, is generally to distinguish between devices, components, steps or functions unless expressly stated otherwise. Additionally, one or more devices or components described with respect to the exemplary embodiments can facilitate one or more functions, where the facilitating (e.g., facilitating access or facilitating establishing a connection) can include less than every step needed to perform the function or can include all of the steps needed to perform the function. 
     In one or more embodiments, a processor (which can include a controller or circuit) has been described that performs various functions. It should be understood that the processor can be multiple processors, which can include distributed processors or parallel processors in a single machine or multiple machines. The processor can include virtual processor(s). The processor can include a state machine, application specific integrated circuit, and/or programmable gate array including a Field PGA, or state machine. In one or more embodiments, when a processor executes instructions to perform “operations”, this can include the processor performing the operations directly and/or facilitating, directing, or cooperating with another device or component to perform the operations. 
     The Abstract of the Disclosure is provided with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.