Abstract:
A system and method for dynamically tuning antenna elements is disclosed. The method comprises: receiving requests to capture over the air broadcasts; selecting an antenna element from a group of available antenna elements to capture one of the requested over the air broadcasts; applying default settings to tune the selected antenna element to capture the one of the requested over the air broadcasts; and dynamically tuning the selected antenna element to enhance reception of the one of the requested over the air broadcasts. The method may further comprise measuring parameters toward optimizing the selected antenna element. The method may also include maintaining the tuning of the selected antenna element until the received request is automatically released because time has elapsed. The method may additionally include recording and/or streaming the requested broadcast to an end-user.

Description:
INCORPORATION BY REFERENCE/CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. Pat. No. 9,118,304, filed on Jan. 31, 2013, and issued on Aug. 25, 2015, which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/652,694, filed on May 29, 2012, both of which are hereby incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Television programming is broadcast by broadcasting entities on different television channels. Some examples of well-known television networks in the United States include ABC, CBS, FOX, NBC, and PBS. 
         [0003]    In general, the channels map to frequency ranges within the radio frequency (RF) spectrum. For example, in the United States channel 2 is broadcast between 54-60 MegaHertz (MHz), channel 3 is broadcast between 60-66 MHz, and channel 4 is broadcast between 66-72 MHz, to list a few examples. 
         [0004]    Recently, systems having arrays of small RF antenna elements have been deployed for capturing the over the air content. The systems then stream the captured content to users via public networks, such as the Internet, and/or private networks. An example of a system for capturing and streaming over the air content to users via the Internet is described in, “System and Method for Providing Network Access to Antenna Feeds” by Kanojia et al., filed Nov. 17, 2011, U.S. patent application Ser. No. 13/299,186, (U.S. Pat. Pub. No. US 2012/0127374 A1), which is incorporated herein by reference in its entirety. 
         [0005]    In these capture systems, each user is assigned their own antenna element. Thus, the systems generally include arrays having large numbers of physically small antenna elements. In order to maximize the number of antenna elements at installation locations, the antenna elements are implemented on antenna array cards in two dimensional arrays and are preferably deployed in three dimensional arrays. Generally, the three dimensional arrays are created by stacking the antenna array cards. 
       SUMMARY OF THE INVENTION 
       [0006]    Because the antenna elements are physically small and the arrays are preferably dense, the capture systems should be located physically near to television transmitters of the broadcasting entities. This ensures a strong signal and compensates for the low gain characteristics of the physically small antenna elements and any other attenuation effects due to the density of the arrays. Additionally, in arrays where there is limited (or no) a priori knowledge of frequency, phasing, or amplitude, the design and configuration of the array is unable to account for coupling (or interference) between antenna elements. 
         [0007]    Unlike antenna elements in a phased array, it is not desirable to have multiple antenna elements competing over the same incident power. To minimize coupling between antenna elements, users are not assigned randomly to antenna elements within the array. Instead, they are selectively assigned to antenna elements based on which channels are requested by the users and to which channels the other antenna elements are already tuned. 
         [0008]    Despite attempts to minimize coupling between antenna elements, at least some coupling is unavoidable due to the array density. The present system is directed to dynamically tuning antenna elements to enhance reception and reduce coupling of the antenna elements in the array. By implementing tuning controls, the antenna elements can be tuned based on measured parameters to reduce destructive effects due to coupling between the antenna elements. 
         [0009]    In general, according to one aspect, the invention features a method for dynamically tuning antenna elements. The method comprises receiving requests to capture over the air broadcasts, selecting an antenna element from a group of available antenna elements to capture one of the requested over the air broadcasts, and dynamically tuning the selected antenna element to enhance reception of one of the requested over the air broadcasts. 
         [0010]    In embodiments, the method further comprises measuring parameters of the selected antenna element to determine how to optimize the selected antenna element. The parameters typically include received power, signal quality, temperature of the antenna element, and/or automatic gain control, which can be prioritized. Preferably the method further comprises adjusting a control voltage of a varactor diode pair based on the measured parameters to tune the selected antenna element. 
         [0011]    In examples, an optimization algorithm is used to yield a divergence of the measured parameters. The optimization algorithm can be a conjugate gradient algorithm, mapping techniques, or ad hoc algorithm. 
         [0012]    Impedances matching is also preferably employed between the antenna elements and tuners with impedance matching circuits. 
         [0013]    In some cases parameter limits are applied to prevent dynamically tuning antenna elements above a distance threshold or above a frequency threshold. 
         [0014]    In other examples, the method may further comprise maintaining the tuning of the selected antenna element until the received request is released. In some instances this release may be related to a time attribute associated with a request to capture over the air broadcasts, wherein the time attribute identifies at least a broadcast expiration time. In this instance, the method may further automatically release the selected antenna element after the broadcast expiration time. In some examples, the time attribute may further identify a broadcast start time, in which case selecting the antenna element from the group of available antenna elements may automatically occur before the broadcast start time. 
         [0015]    In still other examples, the method may further comprise recording the one of the requested over the air broadcasts into a memory associated with an end-user that submitted a request to capture the one of the requested over the air broadcasts. The method may still further include transcoding the captured one of the requested over the air broadcasts into a format that is more efficient for storage than the over the air broadcast format. In other examples, the method may comprise transcoding the captured one of the requested over the air broadcasts into a format that is more efficient for streaming to the end-user than the over the air broadcast format. 
         [0016]    In general, according to another aspect, the invention features an antenna element tuning system, comprising a web server that receives requests to capture over the air broadcasts from broadcasting entities and an antenna controller that selects an antenna element from a group of available antenna elements to capture the requested over the air broadcasts and then dynamically tunes the antenna element to enhance reception of the one of the requested over the air broadcasts. In certain instances, the system may measure parameters of the selected antenna element to optimize the selected antenna element. The measured parameters may be selected from the group comprising received power, signal quality, temperature of the antenna element, and automatic gain control. These measured parameters may be used to adjust a varactor diode pair that may be part of the system. 
         [0017]    In some examples, the system may comprise a timer operably connected to the antenna controller such that the selected antenna element is automatically released after the expiration time of the one of the requested over the air broadcasts. This timer may be a countdown timer and may be connected to the antenna controller such that the selected antenna element is tuned and released based on the timing of the one of the requested over the air broadcasts. Alternatively, the timer may be a real time clock in which case the timing of antenna tuning, recording, and/or streaming may be based on actual time. 
         [0018]    The system in some instances may further include memory for storing the one of the request over the air broadcasts. In still other examples, the system may still further include a transcoder to convert the captured one of the requested over the air broadcasts into a format that is more efficient for storage than the over the air broadcast format. Alternatively, a transcoder may be included in the system to convert the captured one of the requested over the air broadcasts into a format that is more efficient for streaming to the end-user than the over the air broadcast format. 
         [0019]    The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; emphasis has instead been placed upon illustrating the principles of the invention. Of the drawings: 
           [0021]      FIG. 1  is a block diagram illustrating a system for the capture and distribution of broadcast television programs. 
           [0022]      FIG. 2  is a schematic perspective view of a three dimensional antenna array including a card cage structure shown in phantom, which functions as an enclosure for the antenna array cards. 
           [0023]      FIG. 3A  is a circuit diagram of an antenna and tuning feed network for an antenna system. 
           [0024]      FIG. 3B  is an alternative embodiment of the circuit diagram and tuning feed network for the antenna system. 
           [0025]      FIG. 4  is a flowchart illustrating the steps the antenna optimize and control system performs to dynamically tune a single antenna element. 
           [0026]      FIG. 5  is a flowchart illustrating the steps the antenna optimize and control system performs to dynamically tune antenna elements where there is no a priori knowledge of the antenna elements. 
           [0027]      FIG. 6  is a flowchart illustrating the steps the antenna optimize and control system performs to dynamically tune antenna elements where there is prior knowledge of the antenna elements in the array. 
           [0028]      FIG. 7  is a flowchart illustrating the steps the antenna optimize and control system performs to dynamically tune antenna elements with frequency tuning and impedance matching. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0030]    As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Further, the singular forms of nouns and the articles “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms: includes, comprises, including and/or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof Further, it will be understood that when an element, including component or subsystem, is referred to and/or shown as being connected or coupled to another element, it can be directly connected or coupled to the other element or intervening elements may be present. 
         [0031]      FIG. 1  shows a capture system  100  that enables individual users to receive terrestrial television content transmissions captured by antenna elements  102  and streamed to the users. The system  100  allows each user to separately access the feed from a separate antenna element for recording or live streaming of content transmissions. 
         [0032]    In a typical implementation, users access the system  100  via packet network(s), which can be private and/or public, such as the Internet  127 , with client devices  128 ,  130 ,  132 ,  134 . In one example, the client device is a personal computer  134  that accesses the system  100  via a browser. In other examples, the system  100  is accessed by mobile devices such as a tablet or slate computing device, e.g., iPad mobile computing device, or a mobile phone, e.g., iPhone mobile computing device or mobile computing devices running the Android operating system by Google, Inc. Other examples of client devices are televisions that have network interfaces and browsing capabilities. Additionally, many modern game consoles and some televisions also have the ability to run third-party software and provide web browsing capabilities that can be employed to access the video from the system  100  over a network connection. 
         [0033]    The broadcast content is often displayed using HTML-5 or with a media player executing on the client devices such as QuickTime by Apple Corporation, Windows Media Player by Microsoft Corporation, iTunes by Apple Corporation, or Winamp Media Player by Nullsoft Inc., to list a few examples that are currently common. 
         [0034]    An application web server (or application server)  124  manages requests or commands from the client devices  128 ,  130 ,  132 ,  134 . The application server  124  enables the users on the client devices  128 ,  130 ,  132 ,  134  to select whether they want to access previously recorded content transmission, set up recordings of future content transmissions, or watch live broadcast television programs in real time. In some examples, the system  100  also enables users to access and/or record radio (audio-only) broadcasts. 
         [0035]    If the users request to watch previously recorded content transmissions, then the application server  124  sends the request of the user to a streaming server  120 , which retrieves each users&#39; individual copy of the previously recorded content transmission from a broadcast file store (or file store)  126 , if that is where it is resident, and streams the content to the client device  128 ,  130 ,  132 ,  134  from which the request originated. If the users request to set up future recordings of content transmissions such as television programs, the application server  124  communicates with an antenna optimization and control system  116  to configure broadcast capture resources to capture and record the desired content transmissions by reserving antenna and encoding resources for the time and date of the future recording. If the users request to watch live broadcast television programs in real time, the antenna optimization and control system  116  identifies antenna resources available for immediate assignment. 
         [0036]    In current embodiments, streaming content is temporarily stored or buffered in the streaming server  120  and/or the broadcast file store  126  prior to playback and streaming to the users whether for live streaming or future recording. This buffering allows users to pause, rewind, and replay parts of the television program. 
         [0037]    In one implementation, the antenna optimization and control system  116  maintains the assignment of an antenna element  102  to the user throughout any scheduled television program or continuous usage until such time as the user releases the antenna element by closing the session or by the expiration of a predetermined time period as maintained by a timer implemented in the antenna optimization and control system  116 . An alternative implementation would have each antenna element  102  assigned to a particular user for the user&#39;s sole usage. 
         [0038]    The broadcast capture portion of the system  100  includes an array  103  of the antenna elements  102 - 1 ,  102 - 2  . . .  102 - n.  Each of these antenna elements  102 - 1 ,  102 - 2  . . .  102 - n  is a separate antenna element that is capable of capturing different terrestrial television content broadcasts and, through a digitization and encoding pipeline, separately process those broadcasts for storage and/or live streaming to the client devices  128 ,  130 ,  132 ,  134 . This configuration allows the simultaneous recording of over the air broadcasts from different broadcasting entities for each of the users. In the illustrated example, only one array of antenna elements  103  is shown. In a typical implementation, however, multiple two dimensional arrays are used, and in some examples, the arrays are organized into groups of three dimensional arrays. An example of a three dimensional array (which includes arrays  103 - 1  to  103 - n ) is shown in  FIG. 2 . 
         [0039]    The antenna optimization and control system  116  determines which antenna elements  102 - 1  to  102 - n  within the antenna array  103  are available and optimized to receive the particular over the air broadcast content transmissions requested by the users. In a preferred embodiment, the antenna optimization and control system  116  implements an assignment algorithm that optimally assigns users requests to antenna elements  102 - 1  to  102 - n  to minimize the amount of coupling between the antenna elements  102 - 1  to  102 - n.    
         [0040]    In one implementation, determination of optimized antennas is accomplished by comparing received signal strength indicator (RSSI) values of different antenna elements. RSSI is a measurement of the power of a received or incoming radio frequency signal. Thus, the higher the RSSI value, the stronger the received signal. 
         [0041]    In an alternative embodiment, the antenna optimization and control system  116  determines the best available antenna using Modulation Error Ratio (MER). Modulation Error Ratio is used to measure the performance of digital transmitters (or receivers) that are using digital modulation. In short, the antenna element that has the best MER for the desired channel is selected and assigned to receive that channel. 
         [0042]    In the illustrated embodiment, the assignment algorithm avoids assigning user requests to antenna elements if the assigned antenna elements will be blocked by other antenna elements tuned to the same or similar channel. Additionally, if the assigned antenna elements must be tuned to the same or similar channel as other adjacent antenna elements, then the antenna optimization and control system  116  assigns user requests to antenna elements that traditionally have had lower coupling when assigned near other antenna elements tuned to the same or similar channel. 
         [0043]    In scenarios where coupling cannot be avoided, the antenna optimization and control system  116  dynamically tunes the antenna elements  102 - 1  to  102 - n  based on measured parameters. In a typical implementation, the antenna optimization and control system  116  adjust a control voltage sent to varactor diode pairs to dynamically tune the antenna elements  102 - 1  to  102 - n  based on measured parameters of the antenna elements. 
         [0044]    In still other alternative embodiments, other methods to minimize destructive coupling effects, which minimize least mean squared error of the metric being optimized, could also be implemented. 
         [0045]    After identifying antenna elements with adequately minimized coupling, the antenna optimization and control system  116  assigns the user requests to the antenna elements  102 - 1  to  102 - n.  The antenna optimization and control system  116  then signals corresponding RF tuners  104 - 1  to  104 - n  to tune the assigned antenna elements to receive the requested broadcasts. 
         [0046]    The received broadcasts from each of the antenna elements  102 - 1  to  102 - n  and their associated tuners  104 - 1  to  104 - n  are transmitted to an encoding system  105  as content transmissions. The encoding system  105  is comprised of encoding components that create parallel processing pipelines for each allocated antenna  102 - 1  to  102 - n  and tuner  104 - 1  to  104 - n  pair. 
         [0047]    The encoding system  105  demodulates and decodes the separate content transmissions from the antennas  102 - 1  to  102 - n  and tuners  104 - 1  to  104 - n  into MPEG-2 format using an array of ATSC (Advanced Television Systems Committee) decoders  106 - 1  to  106 - n  assigned to each of the processing pipelines. The content transmissions are decoded to MPEG-2 content transmission data because it is currently a standard format for the coding of moving pictures and associated audio information. 
         [0048]    The content transmission data from the ATSC decoders  106 - 1  to  106 - n  are sent to a multiplexer  108 . The content transmissions are then transmitted across an antenna transport interconnect to a demultiplexer switch  110 . In a preferred embodiment, the antenna transport interconnect is an nx10 GbE optical data transport layer. 
         [0049]    The content transmission data of each of the antenna processing pipelines are then transcoded into a format that is more efficient for storage and streaming. In the current implementation, the transcode to the MPEG-4 (also known as H.264) format is effected by an array of transcoders  112 - 1  to  112 - n.  Typically, multiple transcoding threads run on a single signal processing core, SOC (system on a chip), FPGA or ASIC type device. 
         [0050]    The content transmission data are transcoded to MPEG-4 format to reduce the bitrates and the sizes of the data footprints. As a consequence, the conversion of the content transmission data to MPEG-4 encoding will reduce the picture quality or resolution of the content, but this reduction is generally not enough to be noticeable for the average user on a typical reduced resolution video display device. The reduced size of the content transmissions will make the content transmissions easier to store, transfer, and stream to the user devices. Similarly, audio is transcoded to AAC in the current embodiment, which is known to be highly efficient. 
         [0051]    In one embodiment, the transcoded content transmission data are sent to a packetizers and indexers  114 - 1 ,  114 - 2  . . .  114 - n  of the pipelines, which packetize the data. In the current embodiment, the packet protocol is UDP (user datagram protocol), which is a stateless, streaming protocol. 
         [0052]    Also, in this process, time index information is added to the content transmissions. The content data are then transferred to the broadcast file store  126  for storage to the file system, which is used to store and/or buffer the content transmissions as content data for the various content transmission, e.g., television programs, being captured by the users. 
         [0053]    In typical embodiments, the content data are streamed to the users with HTTP Live Streaming or HTTP Dynamic Streaming. These are streaming protocols that are dependent upon the client device. HTTP Live Streaming is a HTTP-based media streaming communications protocol implemented by Apple Inc. as part of its QuickTime X and iPhone software systems. The stream is divided into a sequence of HTTP-based file downloads. HDS over TCP/IP is another option. This is an adaptive streaming communications protocol by Adobe System Inc. HDS dynamically switches between streams of different quality based on the network bandwidth and the computing device&#39;s resources. Generally, the content data are streamed using Hypertext Transfer Protocol (HTTP) or Hypertext Transfer Protocol Secure (or HTTPS). HTTPS combines HTTP with the security of Transport Layer Security/Secure Sockets Layer (or TLS/SSL). TLS/SSL are security protocols that provide encryption of data transferred over the Internet. 
         [0054]      FIG. 2  is a schematic perspective view of an exemplary card cage  151 , which is shown in phantom. The card cage  151  functions as an enclosure to house antenna array cards  152 - 1  to  152 - n  to create a three-dimensional array of antenna elements. The three dimensional array is comprised of multiple two dimensional antenna arrays  103 - 1  to  103 - n.    
         [0055]    The sides  150 - 1 ,  150 - 2 , top  150 - 3 , bottom  150 - 4 , front portions  150 - 5 , and rear  150 - 6  walls of the card cage  151  are fabricated from a conductive material to maximize Faraday shielding of the antenna elements from the active electronics. The front wall  150 - 5  of the card cage provides an open port as the boresight  201  of the antenna arrays  103 - 1  to  103 - n  and faces a television transmitter  204  of the broadcasting entity. Some examples of broadcasting entities include The American Broadcasting Company (ABC), The National Broadcasting Company (NBC), CBS broadcasting corporation (CBS), and The Public Broadcasting Service (PBS). The rear wall  150 - 6  of the card cage  151  includes data transport interfaces  211  that connect the antenna array cards  152 - 1  to  152 - n  to the remainder of the encoding system  250 , which includes the transcoders  112 - 1  to  112 - n,  packetizers and indexers  114 - 1  to  114 - n,  and broadcast file store  126  (shown in  FIG. 1 ). The transcoders  112 - 1  to  112 - n,  packetizers and indexers  114 - 1  to  114 - n,  and file store  126  are preferably located in a secure location such as a ground-level but or the basement of a building, which provides protection from weather and elements and generally has better control over the ambient environment. 
         [0056]    In a current embodiment, each antenna array  103 - 1  to  103 - n  includes  80  antenna elements that are located outside the Faraday shielding of the card cage  151 . Typically, the antenna elements are dual loop antennas. Thus, in the current embodiment with  80  antenna elements, there are 160 loop antennas. In alternative embodiments, as many as 320 antenna elements (640 loops antennas) or possibly 640 antenna elements (1280 loops antennas) are installed on each antenna array card  152 - 1  to  152 - n.  Each antenna is approximately 0.5 inches in height, 0.5 inches wide, or about 1 centimeter (cm) by 1 cm, and has a thickness of approximately 0.030 inches, or about a 1 millimeter (mm). In terms of the antenna elements, when configured as a square loop, the 3 sided length is preferably less than 1.7 inches (4.3 cm), for a total length of all 4 sides being 2.3 inches, (5.8 cm). 
         [0057]    Air dams  210 - 1  to  210 - n  divide the antenna arrays  103 - 1  to  103 - n  from the tuner demodulator sections  111 - 1  to  111 -n. The air dams  210 - 1  to  210 - n  act to block the airflow for the antenna array cards  152 - 1  to  152 - n  and fill in the gap between the cards such that the air dam of each card engages the backside of its adjacent card. Additionally, the air dams  210 - 1  to  210 - n  also act as part of the Faraday shields to reduce electromagnetic interference (EMI). 
         [0058]    Typically, the antenna array cards  152 - 1  to  152 - n  are orientated vertically, with the antenna elements horizontal to create a horizontally polarized (Electric Field) half omni-directional antenna array. Additionally, the antenna elements protrude out of the front of card cage  208  to further help reduce interference between the components (e.g., tuner and demodulators) and the antenna arrays  103 - 1  to  103 - n.    
         [0059]    Alternatively, if over the air content from the broadcasters has a vertical polarization, which occurs in some locales, then orientation of the antenna array cards  152 - 1  to  152 - n  and antennas should be changed accordingly. The illustrated example shows the orientation of the antennas for broadcasters with horizontal polarization. 
         [0060]      FIG. 3A  is a circuit diagram of a multi-band antenna  102 - 1  and tuning feed network  200  for an antenna system  100 , which has been constructed according to the principles of the present invention. 
         [0061]    In the illustrated circuit diagram, a multi-band antenna element  102 - 1  is shown as a dual band antenna. In the illustrated example, the antenna element  102 - 1  further includes a low frequency antenna element  102 A- 1  and a high frequency antenna element  102 B- 1 . In alternative embodiments, however, additional antenna elements could be implemented to form a tri-band antenna or a multi-band antenna with three or more antenna elements. In still other embodiments, the antenna is constructed from only a signal antenna element that covers both bands of interest or only a signal band. 
         [0062]    In a typical implementation, the low and high frequency antenna elements  102 A- 1 ,  102 B- 1  are electrically small loop antennas. Loop antennas have an inductance that is proportional to the area carved out by the loops. Here, the antenna elements  102 A- 1 ,  102 B- 1  are rectangular. Other shapes such as circular shaped loop antennas known in the art could also be implemented. Electrically small antennas are defined for a particular wavelength lambda (X) and radius “a” of the sphere enclosing an antenna. Then, if 4πa&lt;λ(4*pi*a is less than lambda), the antenna is considered electrically small. See Wheeler, “Fundamental limitations of Small Antennas, Proceedings of the IRE, Vol. 35, December 1947, pp. 1479-1484. 
         [0063]    Generally, the antenna element  102 - 1  is multiply resonant. This enables the antenna element  102 - 1  to have optimal performance at a wide range of frequencies and reject interference from other signals that may be in the same band as the desired signal. 
         [0064]    In general, smaller antennas are preferable to achieve higher density, yet smaller antennas typically have a lower gain. As a result in other embodiments larger antennas/antenna elements are used, such as antennas/antenna elements with a total length of up to 20 cm, or even up to 50 cm or 100 cm, and possibly even larger understanding that there is a concomitant decrease in packing density. 
         [0065]    A resonance of the antenna element  102 - 1 , and each of the other antenna elements  102 - 2  to  102 - n,  is controlled via a respective tuning feed network  200 . The tuning feed network  200  includes a radio frequency (RF) coupling and direct current (DC) injection section  203 , a high frequency tuning section  205 , and a low frequency tuning section  207 . In a typical implementation, the components of the tuning feed network  200  are mounted on the antenna array card (e.g.,  152 - 1  to  152 - n  in  FIG. 2 ) adjacent to the antenna element  102 - 1 . 
         [0066]    In the illustrated example, the low frequency tuning section  207  and low frequency antenna element  102 A- 1  are designed to receive carrier signals in the VHF (Very High Frequency) range or 174 MHz to 216 MHz. The high frequency tuning section  205  and high frequency antenna element  102 B- 1  are designed to receive carrier signals in the UHF (Ultra High Frequency) range or 470 MHz to 700 MHz. 
         [0067]    In a typical implementation, antenna elements (e.g., reference numerals  102 - 1  to  102 - n  in  FIG. 1 ) are grouped together on an antenna array card (reference numerals  152 - 1  to  152 - n  in  FIG. 2 ) to form an antenna array (reference numerals  103 - 1  to  103 - n  in  FIG. 2 ) of antennas. Each antenna element  102 - 1  to  102 - n  within the antenna array  103  is tuned by a separate tuning feed network  200 . Implementing a separate tuning feed network  200  for each antenna  102 - 1  to  102 - n  enables each antenna to be individually tuned to a different frequency. 
         [0068]    Returning to  FIG. 3A , a RF connection from the low frequency tuning section  207  to low frequency antenna element  102 A- 1  is made via capacitors C 1  and C 3 . Capacitors C 1  and C 3  have a capacitance of 2.2 nanoFarads, in one example, and these capacitors form a DC block (low frequency tuning section DC block  214 ). A DC block is a frequency filter designed to filter out lower frequency signals and DC signals while allowing higher frequency RF signals to pass. Additionally, the low frequency tuning section DC block  214  prevents the low frequency antenna element  102 A- 1  from shorting out a tuning voltage sent from the RF coupling and DC injection section  203 . 
         [0069]    In alternative embodiments, the RF connection is made with band pass filters, high pass filters, diplexers and/or multiplexers. 
         [0070]    Capacitors C 1  and C 3  connect to low frequency tap points  220   a,    220   b  of the low frequency antenna element  102 A- 1 . The low frequency tap points  220   a,    220   b  are designed to present the desired impedance from the low frequency antenna element  102 A- 1  to the feed lines FEED_P, FEED_N. The location of the intersection of the low frequency tap points  220   a,    220   b  with the low frequency antenna element  102 A- 1  and the area cut out between the tap structure contribute to the impedance transformation. 
         [0071]    Capacitors C 2  and C 212  are in parallel with the varactor diode pairs D 1  and D 2 . In the illustrated example, capacitor C 2  has a capacitance of 15 picoFarads and capacitor C 212  has a capacitance of 18 picoFarads. The varactor diodes pairs D 1 , D 2  resonate with the inductance of the low frequency antenna element  102 A- 1  to set the tuning frequency. The bandwidth is determined by the value of resistor R 4  along the parasitic resistances in the wire of the low frequency antenna element  102 A- 1  and the varactor diode pairs D 1  and D 2 . Resistors R 1 , R 2 , and R 3  provide high impedance connections for DC tuning voltages that are supplied on the feed line FEED_P to the varactor diode pairs D 1  and D 2 . The high impedance serves two purposes. First, the high impedance provides isolation to the feed lines FEED_P, FEED_N so that RF signal is not lost. Second, the high impedance provides isolation from the varactor diode pairs D 1  and D 2  so they are not disrupted by other impedance/capacitive effects. 
         [0072]    Referring to the high frequency tuning section  205 , while there are some differences in the components used and their values, the basic functionality of the circuit is the same as the low frequency tuning section  207 . For example, the high frequency antenna element  102 B- 1  is generally identical to the low frequency antenna element  102 A- 1  in a current embodiment. Additionally, capacitors C 4  and C 7  provide an RF connection from the high frequency antenna element  102 B- 1  to the high frequency tuning section  205 . Likewise, capacitors C 4  and C 7  form a DC block (high frequency tuning section DC block  216 ). Capacitors C 4  and C 7  each have a capacitance value of  24  picoFarads (compared to  2 . 2  nanoFarads for C 1  and C 3 ). Resistor R 7  and R 5  provide a high impedance connection for the tuning voltages provided on feed line FEED_P to varactor diode pair D 3 . The parasitic resistances in the wire of the high frequency antenna element  102 B- 1  and the varactor diode pair D 3  set the bandwidth. Lastly, high frequency tap points  222   a,    222   b  are designed to present the desired impedance from the high frequency antenna element  102 B- 1  to the feed lines FEED_P, FEED_N. 
         [0073]    The feed lines (FEED N and FEED_P) connect the high frequency tuning section  205  and the low frequency tuning section  207  to the RF coupling and DC injection section  203 . The feed lines (FEED_N, FEED_P) carry the received RF signal from the antenna elements  102 A- 1 ,  102 B- 1 , to the RF coupling and DC injection section  203 . In a typical implementation, the physical distance from the RF coupling and DC injection section  203  and the antenna elements  102 A- 1 ,  102 B- 1  can be relatively large. For example, in one embodiment the physical distance is twenty or more inches (approximately 0.5 meters). In alternative embodiments, however, the physical distance is only a few inches (e.g., approximately 5 to 8 centimeters). 
         [0074]    The tuning feed network further includes an impedance matching circuit  136 , which matches the impedance between the RF coupling and DC injection section  203  and the high and low frequency tuning sections (reference numerals  205 ,  207 , respectively). Impedance matching circuits help maximize power transfer and provide an additional means to dynamically tune the antenna element. In the illustrated example, an impedance control line (ICNTL)  137  provides a control signal to adjust the impedance matching circuit. In the illustrated example, the impedance matching circuit  136  is located in the antenna section  111  near the antenna elements. 
         [0075]    The RF coupling and DC injection section  203  includes an analog control line (ACNTL) connection  206  and two logical interfaces: DIFF_N  202  coupled with DIFF_P  204 . The two logical interfaces DIFF_N  202 , DIFF_P  204  are differential radio frequency connections that carry received carrier signals to a receiver (or tuner) and demodulator (reference numerals  104 - 1  and  106 - 1  in  FIG. 1 ) that are located on an antenna array card (reference numeral  152  in  FIG. 2 ). The ACNTL connection  206  is a single-ended analog control line that is referenced to ground (e.g., GND- 1 ) and provides the control signal, to tune the varactor diode pairs D 1 , D 2 , D 3 . In the current embodiment, the control signal is a tuning voltage. In the illustrated embodiment, the control signal from the ACNTL connection  206  is generated by the antenna optimization and control system  116 . The control signal from the antenna optimization and control system  116  is converted to a voltage by a digital to analog converter  170 . A common tuning voltage is provided to the low and high frequency tuning sections  205 ,  207  and the antenna elements  102 A- 1 ,  102 B- 1 . 
         [0076]    In an alternative embodiment, the control signal could be a differential control signal. In this embodiment, another input control signal is injected at GND- 2  and connected at the end of resistor R 6  (GND- 2  would be removed/replaced). 
         [0077]    Capacitors C 5  and C 8  are blocking capacitors and form a DC block (RF coupling and DC injection DC block  208 ). The RF coupling and DC injection DC block  208  provides the ability to superimpose the control signal from ACNTL connection  206  on the same feed line (FEED_P) as the received carrier signals from the low and high frequency antenna elements  102 A- 1 ,  102 B- 1 . 
         [0078]    Typically, when creating a multi-band antenna, two or more antenna elements are put in parallel. There are several important factors to account for when combining multiple antenna elements. For example, in band (where the antenna is tuned), the impedance as measured at the low frequency tap points  220 A,  220 B will look like a single pole bandpass (complex pole-pair) filter having a desired impedance at the resonant frequency. Below the tuned frequency, the impedance will look like a short circuit. Above the tuned frequency, the impedance will approach an open circuit. When implementing the low frequency tuning section DC block  214 , the low frequency tuning section  207  approaches an open circuit at higher frequencies. 
         [0079]    Because the low frequency antenna element  102 A- 1  looks like an open circuit when the tuning feed network  200  is operating at higher frequencies, the low frequency tuning section  207  is typically able to connect to the high frequency tuning section  205  without issue. However, the high frequency antenna element  102 B- 1  looks like a short circuit when the tuning feed network  200  is operating at lower frequencies. To protect the low frequency antenna element  102 A- 1  when operating at lower frequencies, high frequency tuning section DC block  216  is used to electrically open the high frequency antenna element  102 B- 1 . 
         [0080]    In alternative embodiments, different capacitors values used for the high frequency tuning section DC block  216 . In the illustrated example, the  24  picoFarad capacitor is selected. Similar design considerations are applied when combining additional antennas elements to create tri-band or multi-band antenna elements with, for example, three or more loop antennas. 
         [0081]      FIG. 3B  is an alternative embodiment of the tuning feed network  200  for the antenna system  100 . 
         [0082]    The illustrated example is nearly identical to the circuit diagram of  FIG. 3A . In the illustrated example, however, the impedance matching circuit  136  is located between the DIFF_N  202  and DIFF_P  204  inputs and the RF coupling and DC injection DC block  208  (e.g., capacitors C 5  and C 8 ). Additionally, the impedance matching circuit  136  is located in the tuner and demodulator section  109 . 
         [0083]      FIG. 4  is a flowchart illustrating the steps the antenna optimize and control system  116  performs to dynamically tune an antenna element. In the illustrated example, the antenna optimize and control system  116  has no prior information about the antenna elements within the array. 
         [0084]    In the first step  304 , the antenna optimize and control system  116  determines if a new channel is requested by a user. If a new channel is not requested by the user, then the antenna optimize and control system  116  waits until a new channel is requested. 
         [0085]    If a new channel is requested by the user, then the antenna optimize and control system  116  selects an optimized antenna element and applies default settings of the selected antenna element for the requested channel in step  306 . In the next step  308 , the antenna optimize and control system  116  measures parameters of the antenna elements. In a preferred embodiment, the measured parameters include received power of the antenna element, signal quality of the antenna element, temperature of the antenna element, impedance of the antenna element, and/or automatic gain control level, to list a few examples. 
         [0086]    In the next step  310 , the antenna optimize and control system  116  calculates a divergence for each measured parameter. The divergence is calculated to provide a vector derivative based on coupling of all antenna elements. In a typical implementation, the divergence is calculated via a conjugate gradient, mapping techniques, or using ad hoc optimization algorithms. Alternative implementations may implement other methods to calculate the divergence, which are known in the art. 
         [0087]    Next, in step  312 , the antenna optimize and control system  116  applies limits for the parameters. This is done so that antenna elements that do not need to be adjusted are ignored. In a typical implementation, the users are selectively assigned antenna elements throughout the array to minimize coupling between adjacent antenna elements. Thus, in some scenarios, the antenna elements will not need to be adjusted (even though they could be adjusted) because the antenna elements are able to adequately receive the requested channel using the default tuning parameters. That is, the additional tuning of the antenna element would only provide a minimal (or negligible) increase in the quality of the received signal. 
         [0088]    In the next step  314 , the antenna optimize and control system  116  applies parameter weights to prioritize the measured parameters. Each parameter measured in the tuning process is multiplied by a pre-defined constant (weight). An increased weight will increase the impact a parameter has on the tuning algorithm. A smaller weight will cause a parameter to have less impact on the tuning algorithm. A weight of zero will eliminate the impact of a parameter. Thus, parameters with higher weights have higher impact and higher priority. 
         [0089]    In the next step  316 , the antenna optimize and control system  116  adjusts the tuning of the selected antenna element based on the modified parameters. 
         [0090]    In the next step  318 , the antenna optimize and control system  116  determines if a new channel is requested by a user. If a new channel is not requested by the user, then the antenna optimize and control system  116  returns to step  308  to measure parameters of the antenna elements. If a new channel is requested by the user, then the antenna optimize and control system  116  returns to step  306  to apply default settings of the newly requested channel. 
         [0091]      FIG. 5  is a flowchart illustrating the steps the antenna optimize and control system  116  performs to dynamically tune antenna elements  102 - 1  to  102 - n.  In this embodiment, there is no prior information about the measured parameters of the antenna elements  102 - 1  to  102 - n.    
         [0092]    In general, because there is no prior knowledge about the measured parameters, information about all the antennas must be measured before elements can be adjusted. This is because any adjustment to one antenna element can affect other antenna elements within the array. By measuring all the parameters of all the antenna elements first, the antenna elements are tuned with respect to the other antennas. 
         [0093]    In the illustrated example, steps  402 - 410  are identical to steps  302 - 310  of  FIG. 4 . 
         [0094]    In the next step  412 , the antenna optimize and control system  116  ignores null effect controls from other antenna elements (i.e., not the selected antenna element). In a preferred embodiment, the null effect controls are antenna elements, which are not close in physical distance or tuned frequency to cause interference (e.g., coupling) with the selected antenna. In a typical implementation, the antenna optimize and control system  116  includes predefined frequency and distance thresholds. If the other antenna elements exceed the thresholds, then the antenna optimize and control system  116  ignores the measured parameters from these antenna elements. In a preferred embodiment, the frequency threshold is one channel higher or lower than the channel of the selected antenna element. In a preferred embodiment, the distance threshold is the physical distance between antennas such that the coupling while on the same channel is less than or equal to −20 decibels. 
         [0095]    Lastly, in the illustrated example, steps  414  to  420  are identical to steps  312 - 318  of  FIG. 4 . 
         [0096]      FIG. 6  is a flowchart illustrating the steps the antenna optimize and control system  116  performs to dynamically tune antenna elements. In this embodiment, there is prior knowledge of the parameters of the antenna elements. 
         [0097]    Steps  502 - 506  are nearly identical to steps  302 - 310  of  FIG. 4 . In the illustrated example, multiple threads (i.e., independent sequences) are created for each new channel requested by individual users (shown as steps  504 - 1  to  504 - n ). 
         [0098]    The prior knowledge of the antenna elements enables the antenna optimize and control system  116  to ignore antenna elements above predefined distance and frequency thresholds in steps  508  and  510 , respectively. 
         [0099]    In the next step  512 , the antenna optimize and control system  116  measures parameters of the antenna elements. In the next step,  514 , the antenna optimize and control system  116  measures parameters and calculates the divergence for the parameters of the antenna elements. 
         [0100]    In the next step  516 , the antenna optimize and control system  116  removes null effect controls to further ignore antenna elements that will not have an effect on the selected antenna. Even though some antenna elements were ignored in steps  508  and  510 , the antenna optimize and control system  116  ignores additional antennas elements in step  516  because new users are being assigned antennas, current users are stopping their service (i.e., discontinuing use of assigned antennas), and current users are also changing channels. 
         [0101]    Lastly, in the illustrated example, steps  518  to  524  are identical to steps  312 - 328  of  FIG. 3 . 
         [0102]      FIG. 7  is a flowchart illustrating the steps the antenna optimize and control system  116  performs to dynamically tune antenna elements with frequency tuning and impedance matching. 
         [0103]    Similar to step  504 - 1  to  504 - n  in  FIG. 6 , multiple threads  604 - 1  to  604 - n  are created for each new channel requested by different users. In the first step  604 , the antenna optimize and control system  116  determines if a new channel is requested by a user. 
         [0104]    If a new channel is not requested by the user, then the antenna optimize and control system  116  waits until a new channel is requested. If a new channel is requested, then, the antenna optimize and control system  116  applies default settings for the elected antenna element for the requested channel in step  606 . 
         [0105]    In the next step  608 , the antenna optimize and control system  116  determines if the last adjacent frequency has been adjusted. If the last adjacent frequency has not been adjusted, then the antenna optimize and control system  116  performs frequency tuning (e.g.,  FIGS. 4-6 ) for the antenna elements in step  610 . 
         [0106]    If the last adjacent frequency has been adjusted, then the antenna optimize and control system  116  performs impedance matching for the antenna elements in step  612 . In a typical implementation, the impedance matching is performed by the impedance matching circuit (e.g., reference numeral  136  in  FIGS. 3A-3B ). 
         [0107]    In the next step  614 , the antenna optimize and control system  116  determines if a new channel is requested. If a new channel is not requested, then the antenna optimize and control system  116  returns to step  608 . If a new channel is requested, then the antenna optimize and control system  116  applies defaults settings of the selected antenna element for the requested channel in step  606 . 
         [0108]    While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.