Abstract:
The present disclosure provides techniques for configuring multiple element antenna arrays for use in multiple input multiple output (MIMO) communications. The antenna arrays include a ground plane and antenna elements. The ground plane forms an electrically conductive surface having a ground potential. The antenna elements, located near the ground plane, transmit and receive a wireless communication signals over a predetermined wireless channel.

Description:
FIELD OF THE INVENTION 
       [0001]    The present disclosure relates generally to communication systems, and, more particularly, to an antenna array for multiple in multiple out (MIMO) communication systems. 
       BACKGROUND OF THE INVENTION 
       [0002]    A multiple-input multiple-output (MIMO) communication system employs multiple transmit antennas (N T ) and multiple receive antennas (N R ) for data transmission. A MIMO channel formed by the transmit antennas N T  and the receive antennas N R  may be decomposed into independent channels (N S ), with N S  min {N T , N R }. Each of the independent channels N S  is also referred to as a spatial sub-channel of the MIMO channel and corresponds to a dimension. The MIMO system can provide improved performance (e.g., increased transmission data throughput and communication range, without using additional bandwidth or transmit power) over that of a single-input single-output (SISO) communication system, if the additional dimensionalities created by the multiple transmit and receive antennas are utilized. 
         [0003]    To provide wireless connectivity between a portable processing device (e.g., laptop computer) and other computers (laptops, servers, etc.), peripherals (e.g., printers, mouse, keyboard, etc.), or communication devices (modems, cellular phones, smart phones, etc.) it is necessary to equip the portable device with an antenna or multiple antennas. For example, multiple antennas may be located either external to the device or integrated (embedded) within the device (e.g., embedded in the display unit). 
         [0004]    Although an embedded antenna design can overcome disadvantages associated with external antenna designs (e.g., less susceptible to damage), embedded antenna designs typically do not perform as well as external antennas. To improve the performance of an embedded antenna, the antenna is preferably disposed at a certain distance from any metal component of the device. Another disadvantage, associated with embedded antenna designs, is that the size of the device typically is increased to accommodate antenna placement, especially when two or more antennas are used. 
         [0005]    The IEEE 802.11 VHT (Very High Throughput) system targets network throughputs over 1 Gbps (gigabits per second) and per link throughput targeting&gt;500 Mbps. The requirement for such a high data rate communications typically uses Multi-user (MU) MIMO techniques where the AP can use 8 to 16 antennas to communicate with clients with 1 to 4 antennas. Higher order MIMO techniques using 8-16 antennas at the AP and clients can also be used to achieve&gt;500 Mbps per link throughput. 
         [0006]    In high order MIMO communication systems, the design of antenna arrays becomes an increasingly important part of the system design. It is also typically desirable to limit the form factor and size of the device. Therefore, it becomes a design challenge to fit a relatively large number of antennas into a relatively small area, without decreasing channel capacity. In addition, it is desirable for convenience of cable distribution to/from antenna array to keep the antennas in close proximity to processing logic. Because of a small area of a final product, high isolation among the array elements is typically desirable, which may decrease the spatial correlation and increase the channel capacity. When designing higher order antenna arrays, several other parameters may also be considered, such as: the leakage, return loss, isolation, correlation, Eigenvalues, radiation pattern, efficiency, directivity, mechanical design, etc. 
         [0007]    Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art of MIMO communication systems and devices, through comparison of such systems and devices with some aspects of the present invention, as set forth in the remainder of the present disclosure with reference to the drawings. 
       SUMMARY OF THE INVENTION 
       [0008]    According to one aspect of the present invention, the present disclosure provides techniques for configuring multiple element antenna arrays for use in multiple input multiple output (MIMO) communications. The antenna arrays comprise a ground plane and antenna elements. The ground plane forms an electrically conductive surface having a ground potential. The antenna elements, located near the ground plane, transmit and receive a wireless communication signals over a predetermined wireless channel. 
         [0009]    According to other aspects of the present invention, the present invention may employ an apparatus, a wireless communication device, and associated means. 
         [0010]    These and other aspects of the present invention will be apparent from the accompanying drawings and from the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    So that the manner in which the above recited features of the present disclosure may be understood in detail, a more particular description, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings, in which like reference numbers designate corresponding elements. It is to be noted, however, that the appended drawings illustrate only certain typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective embodiments. 
           [0012]      FIG. 1  illustrates an example of a multiple in multiple out (MIMO) wireless local area network (WLAN) communication system, in accordance with certain aspects of the present disclosure. 
           [0013]      FIG. 2  illustrates an example of further details of an access point and a user terminal, each employing an antenna array, as shown in the system of  FIG. 1 , in accordance with certain aspects of the present disclosure. 
           [0014]      FIG. 3  illustrates an example of a prototype printed circuit board (PCB) employing and antenna array configuration having eight (8) printed monopole antennas for use with the system, as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure. 
           [0015]      FIG. 4  illustrates an example of a magnified view of a top end of the PCB, as shown in  FIG. 3 , in accordance with certain aspects of the present disclosure. 
           [0016]      FIG. 5  illustrates an example of a graph of efficiency loss versus frequency for the antenna array configuration, as shown in  FIG. 3 , in accordance with certain aspects of the present disclosure. 
           [0017]      FIG. 6  illustrates an example of a graph of correlation coefficients versus frequency for the antenna array configuration, as shown in  FIG. 3 , in accordance with certain aspects of the present disclosure. 
           [0018]      FIG. 7  illustrates an example of a graph of Eigenvalues versus frequency for the antenna array configuration, as shown in  FIG. 3 , in accordance with certain aspects of the present disclosure. 
           [0019]      FIG. 8  illustrates an example of a simulated printed circuit board (PCB) employing an antenna array configuration having five (5) printed monopole antennas and three (3) planar inverted F antennas (PIFA) for use with the system, as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure. 
           [0020]      FIG. 9  illustrates an example of a magnified view of a top end of the PCB, as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
           [0021]      FIG. 10  illustrates an example of a top, right, and rear perspective view of the PCB, as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
           [0022]      FIG. 11  illustrates an example of a graph of return loss versus frequency for the antenna array configuration, as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
           [0023]      FIG. 12  illustrates an example of a graph of coupling versus frequency for the antenna array configuration, as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
           [0024]      FIG. 13  illustrates an example of a graph of efficiency versus frequency for the antenna array configuration, as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
           [0025]      FIG. 14  illustrates an example of a graph of correlation coefficient versus frequency for the antenna array configuration, as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
           [0026]      FIG. 15  illustrates an example of a graph of Eigenvalues versus frequency for the antenna array configuration, as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
           [0027]      FIG. 16  illustrates an example of a simulated printed circuit board (PCB) employing an antenna array configuration having five (5) printed monopole antennas and three (3) donut antennas for use with the system, as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure. 
           [0028]      FIG. 17  illustrates an example of a magnified view of a top end of the PCB, as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
           [0029]      FIG. 18  illustrates an example of a top, right, and rear perspective view of the PCB, as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
           [0030]      FIG. 19  illustrates an example of a graph of return loss versus frequency for the antenna array configuration, as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
           [0031]      FIG. 20  illustrates an example of a graph of coupling versus frequency for the antenna array configuration, as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
           [0032]      FIG. 21  illustrates an example of a graph of efficiency versus frequency for the antenna array configuration, as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
           [0033]      FIG. 22  illustrates an example of a graph of correlation coefficient versus frequency for the antenna array configuration, as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
           [0034]      FIG. 23  illustrates an example of a graph of Eigenvalues versus frequency for the antenna array configuration, as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
           [0035]      FIG. 24  illustrates an example of a prototype printed circuit board (PCB) employing an antenna array configuration having six (6) chip antennas and two (2) planar inverted F antennas (PIFA) for use with the system, as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure. 
           [0036]      FIG. 25  illustrates an example of a magnified view of a top end of the PCB, as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
           [0037]      FIG. 26  illustrates an example of a graph of efficiency loss versus frequency for the antenna array configuration, as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
           [0038]      FIG. 27  illustrates an example of a graph of S-parameters (e.g., return loss and isolation) versus frequency for two adjacent antennas in the antenna array configuration, as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
           [0039]      FIG. 28  illustrates an example of a graph of S-parameters (e.g., return loss and isolation) versus frequency for two adjacent antennas in the antenna array configuration, as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
           [0040]      FIG. 29  illustrates an example of a graph of correlation coefficient versus frequency for the antenna array configuration, as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
           [0041]      FIG. 30  illustrates an example of a graph of Eigenvalues versus frequency for the antenna array configuration, as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
           [0042]      FIG. 31  illustrates an example of a laptop employing a printed circuit board (PCB) employing sixteen (16) chip antennas for use with the system, as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure. 
           [0043]      FIG. 32  illustrates a magnified view of top right corner of the example shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0044]      FIG. 33  illustrates an example of a graph of efficiency loss versus frequency for the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0045]      FIG. 34  illustrates an example of a graph of S-parameters (e.g., return loss and isolation) versus frequency for two adjacent antennas in the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0046]      FIG. 35  illustrates an example of a graph of S-parameters (e.g., return loss and isolation) versus frequency for two adjacent antennas in the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0047]      FIG. 36  illustrates an example of a graph of correlation coefficient versus frequency for the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0048]      FIG. 37  illustrates an example of a graph of Eigenvalues versus frequency for the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0049]      FIG. 38  illustrates an example of a graph of Eigenvalues versus frequency for eight chip antennas across the top of the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0050]      FIG. 39  illustrates an example of a graph of Eigenvalues versus frequency for eight chip antennas across the side of the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0051]      FIG. 40  illustrates an example of a graph of Eigenvalues versus frequency for eight chip antennas around the corner of the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0052]      FIG. 41  illustrates an example of a graph of Eigenvalues versus frequency for eight odd numbered position chip antennas around the corner of the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
           [0053]      FIG. 42  illustrates an example of a laptop employing a printed circuit board (PCB) employing an antenna array configuration having eight (8) monopole antennas for use with the system, as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure. 
           [0054]      FIG. 43  illustrates a magnified view of top right corner of the example shown in  FIG. 42 , in accordance with certain aspects of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0055]      FIG. 1  illustrates an example of a multiple in multiple out (MIMO) wireless local area network (WLAN) communication system with access points (APs) and user terminals (UTs), in accordance with certain aspects of the present disclosure. For simplicity, only one access point  110  is shown in  FIG. 1 . As used herein, the term access point generally refers to a fixed station that communicates with the user terminals and may also be referred to as a base station, node B, or some other terminology. A system controller  130  couples to and provides coordination and control for the access points to other access points or other systems. A user terminal  120  may be fixed or mobile and may also be referred to as a mobile station, a wireless device, a portable device, a communication device, or some other terminology. A user terminal may communicate with an access point, in which case the roles of access point and user terminal are established. A user terminal may also communicate peer-to-peer with another user terminal. 
         [0056]    The MIMO system  100  may be a time division duplex (TDD) system or a frequency division duplex (FDD) system. For a TDD system, the downlink and uplink share the same frequency band. For an FDD system, the downlink and uplink use different frequency bands. The downlink is the communication link from the access points to the user terminals, and the uplink is the communication link from the user terminals to the access points. MIMO system  100  may also utilize a single carrier or multiple carriers for data transmission. 
         [0057]    In order to increase capacity and data throughput, an access point and user terminals may be equipped with higher order antenna arrays, such as eight or sixteen antennas with different polarization directions. For certain aspects of the present disclosure, the user terminal  120  may be a portable device, a portable computer (e.g., laptop), a cellular phone, a peripheral, a modem, a smart phone, a camera, a camcorder, a computer device, a wireless device, a high definition (HD) television set, or any other type of electronic device, etc. 
         [0058]      FIG. 2  illustrates an example of further details of an access point  110  and a user terminal  102 , each employing an antenna array  204  and  202 , respectively, as shown in the system of  FIG. 1 , in accordance with certain aspects of the present disclosure. The access point  110  and the user terminal  102  communicate over a communication channel  206 , otherwise referred to as a link, path, signal, etc. 
         [0059]    The user terminal  102  includes, among other elements well known but not shown, a transmitter (Tx) radio frequency (RF) chain (i.e., path of transmitter elements)  208 , a receiver (Rx) RF chain (i.e., a path of receiver elements)  210 , a controller  214 , and a switch  212 . The user terminal employs the antenna array  202 , including antennas  216 - 226 . 
         [0060]    In the user terminal  102 , antenna  216  in the antenna array  202  is electrically coupled to the switch  212 , otherwise referred to as an antenna switch. The controller  214  controls the switch  212  (as well as other elements, such as the Tx RF chain  208  and the Rx RF chain  210 ), to selectively and electrically couple the antenna  216  to the Tx RF chain  208  and/or the Rx RF chain  210 . Methods or processes for controlling the switch  212 , including methods for communicating in MIMO WLAN systems  100 , are well known to those skilled in the art of such systems. 
         [0061]    In the user terminal  102 , each antenna  216 - 226  is electrically coupled to a different set of set of RF chains, wherein each RF chain includes a switch  212 , a Tx RF Chain  208  and an Rx RF chain  210 . Therefore, in a user terminal  102  employing four antennas, the user terminal  102  also employs four different sets of RF chains. Further, for example, in a user terminal  102  employing eight antennas, the user terminal  102  also employs eight different sets of RF chains. 
         [0062]    The access point  110  includes, among other elements well known but not shown, a transmitter (Tx) radio frequency (RF) chain (i.e., path of transmitter elements)  228 , a receiver (Rx) RF chain (i.e., a path of receiver elements)  230 , a controller  234 , and a switch  232 . The user terminal employs the antenna array  204 , including antennas  236 - 246 . 
         [0063]    In the access point  110 , antenna  236  in the antenna array  204  is electrically coupled to the switch  232 , otherwise referred to as an antenna switch. The controller  234  controls the switch  232  (as well as other elements, such as the Tx RF chain  228  and the Rx RF chain  230 ), to selectively and electrically couple the antenna  236  to the Tx RF chain  228  and/or the Rx RF chain  230 . Methods or processes for controlling the switch  234 , including methods for communicating in MIMO WLAN systems  100 , are well known to those skilled in the art of such systems. 
         [0064]    In the access point  110 , each antenna  236 - 246  is electrically coupled to a different set of set of RF chains, wherein each RF chain includes a switch  232 , a Tx RF chain  228  and an Rx RF chain  230 . Therefore, in an access point  110  employing four antennas, the access point  110  also employs four different sets of RF chains. Further, for example, in an access point  110  employing eight antennas, the access point  110  also employs eight different sets of RF chains. 
         [0065]    In a MIMO system employing TDD, each of the user terminal  102  and the access point  110  employ the switch  212  and the switch  232 , respectively, as shown in  FIG. 2 . Alternatively, in a MIMO system employing FDD, each of the user terminal  102  and the access point  110  each employ a duplexer (not shown in  FIG. 2 ). Since the duplexer separates the signals by frequency, and not by time, the controllers  214  and  234  are not need as controls for a duplexer. 
         [0066]    Generally, MIMO systems (e.g., for WLAN or otherwise) employ antenna arrays in groups of 2, 4, 8, 16, 32, 64, etc., although any number of antenna may be used. For example, as shown in  FIG. 2 , a MIMO system  100  using four individual antennas in each of the antenna arrays  202  (i.e., antennas  216 - 222 ) and  204  (i.e., antennas  236 - 242 ) for the user terminal  102  and the access point  110 , respectively, is referred to as a 4×4 MIMO system  248 . Similarly, by extension, a MIMO system  100  using eight individual antennas in each of the antenna arrays  202  (i.e., antennas  216 - 224 ) and  204  (i.e., antennas  236 - 244 ) for the user terminal  102  and the access point  110 , respectively, is referred to as a 8×8 MIMO system  250 . Further, by extension, a MIMO system  100  using sixteen individual antennas in each of the antenna arrays  202  (i.e., antennas  216 - 226 ) and  204  (i.e., antennas  236 - 246 ) for the user terminal  102  and the access point  110 , respectively, is referred to as a 16×16 MIMO system  252 . 
         [0067]    Any number of antennas may be employed by the user terminal  102  and the access point  110  in the same MIMO system  100 . For example, the user terminal  102 , embodied as a portable phone handset, may have four antennas. The user terminal  102 , embodied as a laptop, may have eight antennas. The user terminal  102 , embodied as a high definition television, may have sixteen antennas. Further, for example, the access point  110  may have any number of antennas, such as 2, 3, 4, 5, . . . 16, . . . , etc. In combination, the user terminal  102  and the access point  110  may employ a different number of antennas. For example, the user terminal  102  may employ 2 antennas and the access point may employ 3 antennas. Further, for example, the user terminal  102  may employ four antennas and the access point may employ eight or sixteen antennas. Therefore, the MIMO system  100  is not limited to the same and/or an even number of antennas for each of the user terminal  102  and the access point  110 , as shown in  FIG. 2  as 4×4, 8×8, and 16×16. 
         [0068]    Although it is known that increasing the number of antenna elements in an antenna array in a MIMO system increases data throughput and efficiency, mechanical and electrical engineering challenges exist to employ increased number of antenna elements in progressively smaller, lower cost devices, especially in user terminals  102  implemented as mobile communication devices, such as cellular telephones, printed circuit cards, and laptops, for example. 
         [0069]    Exemplary Antenna Arrays 
         [0070]    The present disclosure describes six examples of configurations for an antenna array employed on the user terminal and/or on the access point, as shown in  FIGS. 1 and 2 . The example antenna array configurations are on a printed circuit board (PCB) embodied in a printed circuit (PC) card or in a laptop. The example antenna array configurations have been tested using real or simulated channel measurements. The example antenna array configurations support 8×8 and 16×16 MIMO antenna arrays embodied in a user terminal  120 , as well as space division multiple access (SDMA) using sixteen (16) antennas with an access point  110 . Concepts embodied within the various examples include using different types of antennas with different field patterns positioned at different locations and different directions to achieve a desired performance in a relatively small area for a desired cost. 
         [0071]    Generally,  FIGS. 3 to 7  illustrate an example of a prototype printed circuit board (PCB) employing and antenna array configuration having eight (8) printed monopole antennas for use with the system, as shown in  FIGS. 1 and 2 , and associated performance graphs to support 8×8 MIMO.  FIGS. 8 to 15  illustrate an example of a simulated PCB employing an antenna array configuration having five (5) printed monopole antennas and three (3) planar inverted F antennas (PIFA) for use with the system  100 , as shown in  FIGS. 1 and 2 , and associated performance graphs to support 8×8 MIMO.  FIGS. 16-23  illustrate an example of a simulated PCB employing an antenna array configuration having five (5) printed monopole antennas and three (3) donut antennas for use with the system  100 , as shown in  FIGS. 1 and 2 , and associated performance graphs to support 8×8 MIMO.  FIGS. 24-30  illustrate an example of a prototype PCB employing an antenna array configuration having six (6) chip antennas and two (2) planar inverted F antennas (PIFA) for use with the system  100 , as shown in  FIGS. 1 and 2 , and associated performance graphs to support 8×8 MIMO.  FIGS. 31-41  illustrate an example of a laptop employing a PCB employing an antenna array configuration having sixteen (16) chip antennas for use with the system  100 , as shown in  FIGS. 1 and 2 , and associated performance graphs to support 16×16 MIMO.  FIGS. 42 and 43  illustrate an example of a laptop employing a PCB employing an antenna array configuration having eight (8) monopole antennas for use with the system  100 , as shown in  FIGS. 1 and 2  to support 8×8 MIMO. 
         [0072]    Some of the examples illustrated are lab built prototypes (e.g.,  FIGS. 3-4 ,  24 - 25 ,  31 - 32 , and  42 - 43 ), and some of the examples are computer simulations (i.e., a particular software program) (e.g.,  FIGS. 8-10 , and  16 - 18 ). The lab built prototypes provide a relatively accurate representation of high volume production parts or devices, with regards to shape, size, location, position, etc., for each of the antennas, ground plane, PCB, etc. The electrically conductive paths (e.g., coaxial paths) and connectors (e.g., coaxial connectors) connected to each path, however, are somewhat large and expensive, and not representative of typical, known embodiments of high volume production parts or devices. Production embodiments may include conductive paths represented as coaxial traces printed on the PCB, and connectors represented as miniature, low profile coaxial connectors. Nevertheless, the prototype conductive paths and connectors provide a prototype that may be readily built to test the electrical performance of the prototypes to see if the prototypes meet production performance requirements. 
         [0073]    The computer simulations also provide a relatively accurate representation of high volume production parts or devices, with regards to shape, size, location, position, etc., for each of the antennas, ground plane, PCB, etc. Some of the computer simulations have been tested and compared against actual physical prototype designs, although such comparisons are not shown and described in this disclosure. The comparisons, however, indicate that the computer simulations are very close or nearly identical to the actual physical prototype designs, which verifies the quality, accuracy, and integrity of the computer simulations. Armed with confidence in the computer simulations, designers may build and test various simulated antenna array configurations much faster than building and testing actual physical prototype designs. Further, the computer simulations do not show the electrically conductive paths and connectors for each antenna in the array because such electrical information is embodied in the computer simulation itself, and is not necessary to illustrate mechanically. In summary, each of the actual physical prototype designs and the computer simulations advantageously provide a relatively accurate representation of high volume production parts or devices, both mechanically and electrically. 
         [0074]    For certain examples, channel measurements may be performed with the Antenna Measurement Platform (AMP) 4×4 MIMO channel sounder developed, for example, at Qualcomm, Inc., and enhanced to enable 8×8 and 16×16 MIMO antenna configurations and channel measurements. 
         [0075]    In order to satisfy the system requirements and choose a suitable antenna, system engineers evaluate an antenna&#39;s performance. Typical descriptions, metrics or parameters used in evaluating an antenna include, for example, the bandwidth, return loss, isolation, correlation, Eigenvalues, mechanical design, size, cost, and manufacturability, etc. 
         [0076]    Bandwidth may be described as the range of frequencies within which the performance of the antenna, with respect to some characteristic, conforms to a specified standard. In other words, bandwidth depends on the overall effectiveness of the antenna through a range of frequencies, so these parameters must be understood to fully characterize the bandwidth capabilities of an antenna. In practice, bandwidth is typically determined by measuring a characteristic such as SWR or radiated power over a frequency range of interest. For example, the SWR bandwidth is typically determined by measuring the frequency range where the SWR is less than 2:1. 
         [0077]    Return loss or reflection loss is the reflection of signal power resulting from the insertion of a device, such as an antenna, in a transmission line or optical fiber. It is usually expressed as a ratio in dB relative to the transmitted signal power. 
         [0078]    Isolation is the electromagnetic or electrical separation of one electrical element from another, such as among or between multiple antennas in a MIMO communications system. 
         [0079]    In probability theory and statistics, correlation (often measured as a correlation coefficient) indicates the strength and direction of a linear relationship between two random variables. A correlation matrix of n random variables X 1 , . . . , X n  is the n×n matrix whose i,j entry is corr(X i , X j ). If the measures of correlation used are product-moment coefficients, the correlation matrix is the same as a covariance matrix of the standardized random variables X i /SD(X i ) for i=1, . . . , n. Consequently it is necessarily a positive-semidefinite matrix. The correlation matrix is symmetric because the correlation between X i  and X j  is the same as the correlation between X j  and X i . A covariance matrix is a matrix of covariances between elements of a vector. It is the natural generalization to higher dimensions of the concept of the variance of a scalar-valued random variable. 
         [0080]    In linear algebra, a linear transformation between finite-dimensional vector spaces can be expressed as a matrix, which is a rectangular array of numbers arranged in rows and columns. Standard methods may be used for finding eigenvalues, eigenvectors, and eigenspaces of a given matrix. In mathematics, given a linear transformation, an eigenvector of that linear transformation is a nonzero vector which, when that transformation is applied to it, may change in length, but not direction. For each eigenvector of a linear transformation, there is a corresponding scalar value called an eigenvalue for that vector, which determines the amount the eigenvector is scaled under the linear transformation. For example, an eigenvalue of +2 means that the eigenvector is doubled in length and points in the same direction. An eigenvalue of +1 means that the eigenvector is unchanged, while an eigenvalue of −1 means that the eigenvector is reversed in direction. An eigenspace of a given transformation for a particular eigenvalue is the set of the eigenvectors associated to this eigenvalue, together with the zero vector (which has no direction). 
         [0081]    Exemplary Antenna Arrays 
         [0082]    1. PCMCIA Card Having a PCB with Eight (8) Printed Monopole Antennas. 
         [0083]      FIG. 3  illustrates an example of a prototype personal computer memory card international association (PCMCIA) card  300  employing a PCB  302  and antenna array configuration  304  for use with the system  100 , as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure.  FIG. 4  illustrates an example of a magnified view  400  of a top end of the PCMCIA card  300 , as shown in  FIG. 3 , in accordance with certain aspects of the present disclosure. The PCMCIA card  300  may be of the type that connects to other electronic devices, such as a laptop computer, to provide the electronic device with radio frequency (RF) wireless communication capability. 
         [0084]    The PCMCIA card  300  generally includes a printed circuit board  302 , a ground plane  314 , eight (8) printed monopole antennas  306 - 313  (also labeled  1 - 8 , respectively) forming the antenna array  304 , eight (8) electrically conductive paths  315 - 322  (also labeled  1 - 8 , respectively), eight (8) eight connectors  323 - 330  (also labeled  1 - 8 , respectively). 
         [0085]    Each printed monopole antenna is electrically connected to a corresponding connector via a corresponding path. Antenna  306  is connected to connector  323  via path  315 . Antenna  307  is connected to connector  324  via path  316 . Antenna  308  is connected to connector  325  via path  317 . Antenna  309  is connected to connector  326  via path  318 . Antenna  310  is connected to connector  327  via path  319 . Antenna  311  is connected to connector  328  via path  320 . Antenna  312  is connected to connector  329  via path  321 . Antenna  313  is connected to connector  330  via path  322 . 
         [0086]    The PCB  302  may have a width dimension  332  of 60 mm and a length dimension  334  of 125 mm. The ground plane  314  may be centered within a distal end surface of the PCB  302  permitting a non-grounded border portion of the PCB to have a left border dimension  338  of 5 mm, a top border dimension  342  of 5 mm, and a right border dimension  340  of 5 mm. The antenna array  304 , located at the distal end of the PCB  302  has a length dimension  336  of about 32 mm. In  FIG. 4 , each monopole antenna  306 - 313  has a width dimension  344  of 2.3 mm and a length dimension  346  of 8.5 mm. In  FIG. 4 , a separation distance  348  between each monopole antenna  306 - 313  is about 13 mm, corresponding to approximately ¼ wavelength. Other dimensions or features, such as these described as well as other features, shown in  FIGS. 3 and 4 , may be permitted within the scope of the present invention. 
         [0087]    The PCB  302  advantageously supports the ground plane  314  and the printed monopole antennas  306 - 313  in a common plane on a surface of the PCB  302 . Alternatively, when the ground plane and the printed monopole antennas  306 - 313  have a sufficient thickness (e.g., thicker than the thickness typically printed on a PCB) or other self-supporting mechanical structure (e.g., folds, bends, ridges, etc.) the ground plane and the printed monopole antennas  306 - 313  may support itself, without the use of the PCB  302 . 
         [0088]    Regardless of whether a supporting PCB  302  is used in combination with the ground plane  314  or whether the ground plane  314  is used without the PCB  302 , each of the printed monopole antennas  306 - 313  may be located in any plane relative to a plane containing the PCB  302  and/or the ground plane  314 . In the example shown in  FIGS. 3 and 4 , the printed monopole antennas  306 - 313  are all shown and described to be in the same plane as the ground plane  314 , since the printed monopole antennas  306 - 313  and the ground plane  314  are manufactured during the same process. Alternatively, each of the printed monopole antennas  306 - 313  may be located in any position within an imaginary sphere of space surrounding each of the printed monopole antennas  306 - 313 . 
         [0089]    Many positions of each of the printed monopole antennas  306 - 313  may be provided of which a few are described to summarize this concept. In one example, adjacent printed monopole antennas  306 - 313  may be printed on opposite sides of the same PCB  302 . In this example, the printed monopole antennas  306 - 313  have the same relative locations as shown in  FIGS. 3 and 4  when looking at the PCB  302 , as shown in  FIGS. 3 and 4 . However, the even numbered printed monopole antennas  306 ,  308 ,  310 , and  312  are located on the front side of the PCB  302 , as shown in  FIGS. 3 and 4 , and the odd numbered printed monopole antennas  307 ,  309 ,  311 , and  313  are located on the rear side of the PCB  302 , which is different from that shown in  FIGS. 3 and 4 . The odd numbered printed monopole antennas  307 ,  309 ,  311 , and  313  may be located on the rear side of the PCB  302  by using PCB feed thru holes, for example, wherein such holes are well known to those skilled in the PCB art. In this example, the even and odd numbered antenna elements are further separated by the thickness of the PCB  302 , which may improve performance characteristics of the antenna array  304 . 
         [0090]    In another example, when the PCB  302  is not used, even and odd numbered antenna elements may be positioned at various angles relative to each other within a range of 0 to 360 degrees relative to a plane of the ground plane  314 . In  FIGS. 3 and 4 , for example, each of the printed monopole antennas  306 - 313  are located at about +180 degrees relative to a front surface of the ground plane  314 . In an alternative example, the even numbered printed monopole antennas  306 ,  308 ,  310 , and  312  may be located at about +120 degrees relative to the a front surface of the ground plane  314 , and the odd numbered printed monopole antennas  307 ,  309 ,  311 , and  313  may be located at about +240 degrees relative to the a front surface of the ground plane  314 . In this example, the even and odd numbered antenna elements are further separated by an angle of about +120 degrees, which may improve performance characteristics of the antenna array  304 . 
         [0091]    In yet another example, when the PCB  302  is not used, even and odd numbered antenna elements may be positioned at various angles relative to each other within a range of 0 to 360 degrees relative to another plane which is perpendicular to the plane of the ground plane  314 . In this example, the printed monopole antennas  306 - 313  may be conceptually be thought of as being twisted in an out of the plane of the ground plane  314 , as shown in  FIGS. 3 and 4 . In  FIGS. 3 and 4 , for example, each of the printed monopole antennas  306 - 313  are located at about 0 degrees relative to a front surface of the ground plane  314 . In an alternative example, the even numbered printed monopole antennas  306 ,  308 ,  310 , and  312  may be located at about +90 degrees relative to the a front surface of the ground plane  314 , and the odd numbered printed monopole antennas  307 ,  309 ,  311 , and  313  may be located at about −90 degrees relative to the a front surface of the ground plane  314 . In this example, the even and odd numbered antenna elements are further separated by an angle of about +180 degrees, which may improve performance characteristics of the antenna array  304 . 
         [0092]    Each of these examples are not meant to be limited in any way, including to a particular antenna type of construction, and may be used with various antenna types and constructions, such as a ceramic chip package illustrated in  FIGS. 24 ,  25 ,  31 , and  32 . Further, each of these examples are not meant to be limited to a particular antenna location or position. For example, these examples are not limited to even an odd antenna elements, adjacent antenna elements, etc. Further, the angles of the antenna elements may be positioned any angle relative to any plane and in any direction, thereby including all positions and locations within an imaginary space (e.g., sphere, square, rectangle, etc.) 
         [0093]    A monopole antenna may employ various shapes, dimensions, and configurations relative to the ground plane. As illustrated in  FIGS. 3 and 4 , the monopole antenna is provided as a “pointed or tapered flag” shape, having a short and flat shape at a proximate end of the antenna, which gradually tapers along first length side to a pointed shape at a distal end of the antenna. The second length side is long, flat and forms about a right angle with the short and flat shape at the proximate end of the antenna. The short and flat shape at a proximate end of the antenna connects to the corresponding path for each of the corresponding antennas. Alternatively, a monopole antenna may be formed in a ceramic chip package similar to those shown in  FIGS. 24 ,  25 ,  31 , and  32 . 
         [0094]    Individually, various design and engineering details for prototype and production versions of each of the printed circuit board  302  (e.g., FR4), the ground plane  314 , the eight printed monopole antennas  306 - 313 , the eight electrically conductive paths  315 - 322 , and the eight (8) eight connectors  323 - 330 , are well known to those skilled in the art of those individual elements. 
         [0095]    The PCMCIA card  300  has two antennas  306 - 307  located along a left side of the card  300 , four antennas  308 - 311  located along a top of the card  300 , and two antennas  312  and  313  located along a right side of the card  300 . Other configurations of the antenna array  304  are possible and may be used within the scope of the present invention. 
         [0096]    The antenna array  304 , illustrated in  FIGS. 3 and 4 , advantageously permits the PCMCIA card  300 , having dimensions compatible with industry standard dimensions (e.g., length and width), to be adapted for use in an 8×8 MIMO communication system  100 . The antenna array  304 , 8×8 for example, is small enough to fit on a distal end of the PCMCIA card  300  while provide an acceptable antenna radiation pattern, and other acceptable communications characteristics, as further described in  FIGS. 5-7 . 
         [0097]      FIG. 5  illustrates an example of a graph  500  of efficiency loss  509  versus frequency  510  for the antenna array configuration  304 , as shown in  FIG. 3 , in accordance with certain aspects of the present disclosure. The graph  500  represents efficiency loss  509  from 0 to −10 dB. The graph  500  represents frequency range from 4600 to 5800 MHz. A process for measuring efficiency loss  509  versus frequency  510  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 5  illustrates acceptable performance for efficiency loss  509  versus frequency  510  for the antenna array configuration  304 . 
         [0098]    The graph  500  illustrates eight traces  512 , wherein each trace  501 - 508  corresponds to an efficiency loss  509  versus frequency  510  for one the antennas  306 - 313 . In particular, traces  501 ,  502 ,  503 ,  504 ,  505 ,  506 ,  507 , and  508  correspond to antennas  306 - 313 , respectively. 
         [0099]    The data illustrated in the graph  500  includes electrical loss of about 0.2 to 0.3 dB in each of the paths  315 - 322 , which are constructed as coaxial cables in the prototype version of the PCMCIA card  300 . Such electrical loss may not be present in production version of the PCMCIA card  300 , wherein PCB traces on the PCB  302  are used to provide the paths  315 - 322 . Therefore, the efficiency loss  509  for each antenna  306 - 313  versus frequency  510  may improve in the graph  500  by about 0.2 to 0.3 dB in a production version of the PCMCIA card  300 . 
         [0100]      FIG. 6  illustrates an example of a graph  600  of correlation coefficients  609  versus frequency  610  for the antenna array configuration  304 , as shown in  FIG. 3 , in accordance with certain aspects of the present disclosure. The graph  600  represents correlation coefficients  609  from 0 to 1. The graph  600  represents frequency range from 4600 to 5800 MHz. A process for measuring correlation coefficients  609  versus frequency  610  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 6  illustrates acceptable performance for correlation coefficients  609  versus frequency  610  for the antenna array configuration  304 . 
         [0101]    The graph  600  illustrates 28 traces  612 , wherein each trace corresponds to correlation coefficients  609  versus frequency  610  among each pair of the antennas  306 - 313 . For example, one trace represents correlation coefficients  609  versus frequency  610  between antennas  306  and  307 , another represents correlation coefficients  609  versus frequency  610  between antennas  306  and  308 , and so forth. 
         [0102]      FIG. 7  illustrates an example of a graph  700  of Eigenvalues  709  of the covariance matrix versus frequency  710  for the antenna array configuration  304 , as shown in  FIG. 3 , in accordance with certain aspects of the present disclosure. The graph  700  represents Eigenvalues  709  from 0 to −30 dB. The graph  700  represents frequency range from 4600 to 5800 MHz. A process for calculating Eigenvalues  709  versus frequency  710  from the radiation patterns of an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 7  illustrates acceptable performance for Eigenvalues  709  versus frequency  710  for the antenna array configuration  304 . 
         [0103]    The graph  700  illustrates eight traces  712 , wherein each trace corresponds to Eigenvalues  709  versus frequency  710  among the antennas  306 - 313 . The first trace  701  is normalized to 0 dB. In particular, traces  701 ,  702 ,  703 ,  704 ,  705 ,  706 ,  707 , and  708  are sorted according to their magnitude. 
         [0104]    2. PCMCIA Card Having a PCB with Five Monopole Antennas and Three PIFAs. 
         [0105]      FIG. 8  illustrates an example of a simulated PCMCIA card  800  employing an antenna array configuration  804  having five (5) printed monopole antennas  806 - 810  and three (3) planar inverted F antennas (PIFA)  811 - 813  for use with the system  100 , as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure.  FIG. 9  illustrates an example of a magnified view  900  of a top end of the PCMCIA card  800 , as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure.  FIG. 10  illustrates an example of a top, right, and rear perspective view of the PCMCIA card  300 , as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. The PCMCIA card  800  may be of the type that connects to other electronic devices, such as a laptop computer, to provide the electronic device with radio frequency (RF) wireless communication capability. 
         [0106]    The PCMCIA card  800  generally includes a printed circuit board  802 , a ground plane  814 , and five (5) printed monopole antennas  806 - 810  (also labeled  1 - 5 , respectively) and three PIFAs  811 - 813  (also labeled  6 - 8 , respectively), wherein all eight antennas together form the antenna array  804 . Not shown but electrically simulated in  FIGS. 8-10  are eight (8) electrically conductive paths. Each printed monopole antenna is of the type described with reference to  FIGS. 3 and 4  hereinabove. 
         [0107]    The PCB  802  may have a width dimension  832  of 58 mm and a length dimension  834  of 114 mm. The ground plane  814  may have a width dimension  833  of 50 mm and a length dimension  858  of 110 mm. The ground plane  814  may be centered within a distal end surface of the PCB  802  permitting a non-grounded border portion of the PCB to have a left border dimension  838  of 4 mm, a top border dimension  842  of 4 mm, and a right border dimension  840  of 4 mm. The antenna array  304 , located at the distal end of the PCB  302  has a length dimension  836  of about 16 mm. In  FIG. 4 , each monopole antenna  306 - 313  has a width dimension  844  of 2.3 mm and a length dimension  846  of 8.5 mm. In  FIG. 4 , a separation distance  848  between each monopole antenna  806 - 810  is about 15 mm, corresponding to approximately ¼ wavelength. The PIFAs are located a height dimension  856  of 5 mm above the ground plane  814 . Each of the PIFAs has a length dimension  852  of 8 mm and a width dimension  850  of 8 mm. Adjacent PIFAs may be separated by a separation distance  851  of 14 mm. Other dimensions or features, such as these described as well as other features, shown in  FIGS. 8-10 , may be permitted within the scope of the present invention. 
         [0108]    PIFAs are derived from a quarter-wave half-patch antenna. In PIFAs, the shorting plane of the half-patch is reduced in length which decreases the resonance frequency. Often PIFAs have multiple branches to resonate at the various frequency bands, such as those used in cellular applications. In some configurations, grounded parasitic elements are used to enhance the radiation bandwidth characteristics of PIFAs. PIFA antennas may have more bandwidth and better efficiency than chip antennas. 
         [0109]    Individually, various design and engineering details for prototype and production versions of each of the printed circuit board  802  (e.g. FR4), the ground plane  814 , the five printed monopole antennas  806 - 810 , the three PIFAs  811 - 813 , the eight electrically conductive paths (not shown, but simulated), are well known to those skilled in the art of those individual elements. 
         [0110]    The PCMCIA card  800  has one monopole antenna  806  located along a left side of the card  800 , three monopole antennas  807 - 809  located along a top of the card  800 , one monopole antenna  810  located along a right side of the card  300 , and the three PIFAs  811 - 813  located on top of a surface of the ground plane  814  on the PCB  802  and between and somewhat below the monopole antennas  806  and  810 . Other configurations of the antenna array  804  are possible and may be used within the scope of the present invention. 
         [0111]    The antenna array  804 , illustrated in  FIGS. 8-10 , advantageously permits the PCMCIA card  800 , having dimensions compatible with industry standard dimensions (e.g., length and width), to be adapted for use in an 8×8 MIMO communication system  100 . The antenna array  804 , 8×8 for example, is small enough to fit on a distal end of the PCMCIA card  800  while provide an acceptable antenna radiation pattern, and other acceptable communications characteristics, as further described in  FIGS. 11-15 . 
         [0112]      FIG. 11  illustrates an example of a graph  1100  of return loss  1109  versus frequency  1110  providing a measure of return loss for the antenna array configuration  804 , as shown in  FIGS. 8-10 , in accordance with certain aspects of the present disclosure. 
         [0113]    The graph  1100  represents return loss  1109  from 0 to −20 dB. The graph  1100  represents frequency range from 4000 to 6000 MHz. A process for measuring return loss  1109  versus frequency  1110  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 1100  illustrates acceptable performance for return loss  1109  versus frequency  1110  for the antenna array configuration  804 . 
         [0114]    The graph  1100  illustrates eight traces  1112 , wherein each trace  1101 - 1108  corresponds to a return loss  1109  versus frequency  1110  for one of the antennas  806 - 813 . In particular, traces  1101 ,  1102 ,  1103 ,  1104 ,  1105 ,  1106 ,  1107 , and  1108  correspond to antennas  806  through  813 , respectively. 
         [0115]      FIG. 12  illustrates an example of a graph  1200  of antenna coupling  1209  versus frequency  1210  for the antenna array configuration  804 , as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
         [0116]    The graph  1200  represents antenna coupling  1209  from 0 to −20 dB. The graph  1100  represents frequency range from 4000 to 6000 MHz. A process for measuring antenna coupling  1209  versus frequency  1210  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 1200  illustrates acceptable performance for antenna coupling  1209  versus frequency  1210  for the antenna array configuration  804 . 
         [0117]    The graph  1200  illustrates 28 traces  1212 , wherein each trace corresponds to antenna coupling  1209  versus frequency  1210  among the antennas  806 - 813 . For example, one trace represents antenna coupling  1209  versus frequency  1210  between antennas  806  and  807 , another represents antenna coupling  1209  versus frequency  1210  between antennas  806  and  808 , and so forth. 
         [0118]      FIG. 13  illustrates an example of a graph  1300  of efficiency  1309  versus frequency  1310  for the antenna array configuration  804 , as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
         [0119]    The graph  1300  represents efficiency  1309  from 0 to −10 dB. The graph  1300  represents frequency range from 4000 to 6000 MHz. A process for measuring efficiency  1309  versus frequency  1310  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 13  illustrates acceptable performance for efficiency  1309  versus frequency  1310  for the antenna array configuration  804 . 
         [0120]    The graph  1300  illustrates eight traces  1312 , wherein each trace  1301 - 1308  corresponds to an efficiency  1309  versus frequency  1310  for one of the antennas  806 - 813 . In particular, traces  1301 ,  1302 ,  1303 ,  1304 ,  1305 ,  1306 ,  1307 , and  1308  correspond to antennas  806  through  813 , respectively. 
         [0121]      FIG. 14  illustrates an example of a graph  1400  of correlation coefficient  1409  versus frequency  1410  for the antenna array configuration  804 , as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
         [0122]    The graph  1400  represents correlation coefficients  1409  from 0 to 1. The graph  1400  represents frequency range from 4000 to 6000 MHz. A process for measuring correlation coefficients  1409  versus frequency  1410  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 14  illustrates acceptable performance for correlation coefficients  1409  versus frequency  1410  for the antenna array configuration  804 . 
         [0123]    The graph  1400  illustrates 28 traces  1412 , wherein each trace corresponds to correlation coefficients  1409  versus frequency  1410  among the antennas  806 - 813 . For example, one trace represents correlation coefficients  1409  versus frequency  1410  between antennas  806  and  807 , another represents correlation coefficients  1409  versus frequency  1410  between antennas  806  and  808 , and so forth. 
         [0124]      FIG. 15  illustrates an example of a graph  1500  of Eigenvalues  1509  versus frequency  1510  of the covariance matrix for the antenna array configuration  804 , as shown in  FIG. 8 , in accordance with certain aspects of the present disclosure. 
         [0125]    The graph  1500  represents Eigenvalues  1509  from 0 to −30 dB. The graph  1500  represents frequency range from 4000 to 6000 MHz. A process for calculating Eigenvalues  1509  of the covariance matrix from radiation patterns versus frequency  1510  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 15  illustrates acceptable performance for Eigenvalues  1509  versus frequency  1510  for the antenna array configuration  804 . 
         [0126]    The graph  1500  illustrates eight traces  1512 , wherein each trace corresponds to Eigenvalues  1509  versus frequency  1510  among the antennas  806 - 813 . The first trace  1501  is normalized to 0 dB. In particular, traces  1501 ,  1502 ,  1503 ,  1504 ,  1505 ,  1506 ,  1507 , and  1508  are sorted according to their magnitude. 
         [0127]    3. PCMCIA Card Having a PCB with Five Monopole and Three Donut Antennas. 
         [0128]      FIG. 16  illustrates an example of a simulated PCMCIA card  1600  employing an antenna array configuration  1604  having five (5) printed monopole antennas  1609 - 1613  and three (3) donut antennas  1606 - 1608  for use with the system  100 , as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure.  FIG. 17  illustrates an example of a magnified view  1700  of a top end of the PCMCIA card  1600 , as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure.  FIG. 18  illustrates an example of a top, right, and rear perspective view of the PCMCIA card  1600 , as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. The PCMCIA card  1600  may be of the type that connects to other electronic devices, such as a laptop computer, to provide the electronic device with radio frequency (RF) wireless communication capability. 
         [0129]    The PCMCIA card  1600  generally includes a printed circuit board  1602 , a ground plane  1614 , and five (5) printed monopole antennas  1609 - 1613  (also labeled  4 - 8 , respectively) and three donut antennas  1606 - 1608  (also labeled  1 - 3 , respectively), wherein all eight antennas together form the antenna array  1604 . Not shown, but electrically simulated, in  FIGS. 16-18  are eight (8) electrically conductive. Each printed monopole antenna is of the type described with reference to  FIGS. 3 and 4  hereinabove. 
         [0130]    The PCB  1602  may have a width dimension  1632  of 58 mm and a length dimension  1634  of 114 mm. The ground plane  1614  may have a width dimension  1633  of 50 mm and a length dimension  1658  of 110 mm. The ground plane  1614  may be centered within a distal end surface of the PCB  1602  permitting a non-grounded border portion of the PCB to have a left border dimension  1638  of 4 mm, a top border dimension  1642  of 4 mm, and a right border dimension  1640  of 4 mm. The antenna array  1604 , located at the distal end of the PCB  1602  has a length dimension  1636  of about 20 mm. In  FIG. 4 , each monopole antenna  1609 - 1613  has a width dimension  1644  of 3.2 mm and a length dimension  1646  of 11.2 mm. In  FIG. 4 , a separation distance  1648  between each monopole antenna  1609 - 1613  is about 16 mm, corresponding to approximately ¼ wavelength. The donut antennas are located a height dimension  1656  of 5 mm above the ground plane  1614 . Each of the donut antennas has a length dimension  1652  of 10 mm and a width dimension  1650  of 10 mm. Adjacent donut antennas may be separated by a separation distance  851  of 15 mm. Other dimensions or features, such as these described as well as other features, shown in  FIGS. 16-18 , may be permitted within the scope of the present invention. 
         [0131]    Donut antennas are similar to planar inverted F antenna (PIFA) with a feed point and a shorting post connection to ground. Donut antennas may have more bandwidth and better efficiency than chip or monopole antennas. 
         [0132]    Individually, various design and engineering details for prototype and production versions of each of the printed circuit board  1602  (e.g. FR4), the ground plane  1614 , the five printed monopole antennas  1609 - 1613 , the three donut antennas  1606 - 1608 , the eight electrically conductive paths (not shown, but simulated), are well known to those skilled in the art of those individual elements. 
         [0133]    The PCMCIA card  1600  has one monopole antenna  1609  located along a left side of the card  1600 , three monopole antennas  1610 - 1612  located along a top of the card  1600 , one monopole antenna  1613  located along a right side of the card  1600 , and the three donut antennas  1606 - 1608  located above a top of a surface of the ground plane  1614  on the PCB  1602  and between and somewhat below the monopole antennas  1609  and  1613 . Other configurations of the antenna array  1604  are possible and may be used within the scope of the present invention. 
         [0134]    The antenna array  1604 , illustrated in  FIGS. 16-18 , advantageously permits the PCMCIA card  1600 , having dimensions compatible with industry standard dimensions (e.g., length and width), to be adapted for use in an 8×8 MIMO communication system  100 . The antenna array  804 , 8×8 for example, is small enough to fit on a distal end of the PCMCIA card  1600  while provide an acceptable antenna radiation pattern, and other acceptable communications characteristics, as further described in  FIGS. 19-23 . 
         [0135]      FIG. 19  illustrates an example of a graph  1900  of return loss  1909  versus frequency  1910  for the antenna array configuration  1604 , as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
         [0136]    The graph  1900  represents return loss  1909  from 0 to −20 dB. The graph  1900  represents frequency range from 4500 to 6500 MHz. A process for measuring return loss  1909  versus frequency  1910  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 1900  illustrates acceptable performance for return loss  1909  versus frequency  1910  for the antenna array configuration  1604 . 
         [0137]    The graph  1900  illustrates eight traces  1112 , wherein each trace  1901 - 1908  corresponds to return loss  1909  versus frequency  1910  for one the antennas  1606 - 1613 . In particular, traces  1901 ,  1902 ,  1903 ,  1904 ,  1905 ,  1906 ,  1907 , and  1908  correspond to antennas  1606  through  1613 , respectively. 
         [0138]      FIG. 20  illustrates an example of a graph  2000  of antenna coupling  2009  versus frequency  2010  for the antenna array configuration  1604 , as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
         [0139]    The graph  2000  represents antenna coupling  2009  from 0 to −20 dB. The graph  2000  represents frequency range from 4500 to 6500 MHz. A process for measuring antenna coupling  2009  versus frequency  2010  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 2000  illustrates acceptable performance for antenna coupling  2009  versus frequency  2010  for the antenna array configuration  1604 . 
         [0140]    The graph  2000  illustrates 28 traces  2012 , wherein each trace corresponds to antenna coupling  2009  versus frequency  2010  among the antennas  1606 - 1613 . For example, one trace represents antenna coupling  2009  versus frequency  2010  between antennas  1606  and  1607 , another represents antenna coupling  2009  versus frequency  2010  between antennas  1606  and  1608 , and so forth. Some of the coupling traces are less than or equal to 20 dB and not to scale in the graph. 
         [0141]      FIG. 21  illustrates an example of a graph  2100  of efficiency, in terms of efficiency,  2109  versus frequency  2110  for the antenna array configuration  1604 , as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
         [0142]    The graph  2100  represents efficiency  2109  from 0 to −10 dB. The graph  2100  represents frequency range from 4500 to 6500 MHz. A process for measuring efficiency  2109  versus frequency  2110  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 21  illustrates acceptable performance for efficiency  2109  versus frequency  2110  for the antenna array configuration  1604 . 
         [0143]    The graph  2100  illustrates eight traces  2112 , wherein each trace  2101 - 2108  corresponds to an efficiency  2109  versus frequency  2110  for one of the antennas  1606 - 1613 . In particular, traces  2101 ,  2102 ,  2103 ,  2104 ,  2105 ,  2106 ,  2107 , and  2108  correspond to antennas  1606  through  1613 , respectively. 
         [0144]      FIG. 22  illustrates an example of a graph  2200  of correlation coefficient  2209  versus frequency  2210  for the antenna array configuration  1604 , as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
         [0145]    The graph  1600  represents correlation coefficients  1609  from 0 to 1. The graph  1600  represents frequency range from 4500 to 6500 MHz. A process for measuring correlation coefficients  1609  versus frequency  1610  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 22  illustrates acceptable performance for correlation coefficients  1609  versus frequency  1610  for the antenna array configuration  1604 . 
         [0146]    The graph  2100  illustrates 8 traces  2112 , wherein each trace corresponds to correlation coefficients  2109  versus frequency  2110  among the antennas  1606 - 1613 . For example, one trace represents correlation coefficients  2109  versus frequency  2110  between antennas  1606  and  1607 , another represents correlation coefficients  2109  versus frequency  2110  between antennas  1606  and  1808 , and so forth. 
         [0147]      FIG. 23  illustrates an example of a graph  2300  of Eigenvalues  2309  versus frequency  2310  of the covariance matrix for the antenna array configuration  1604 , as shown in  FIG. 16 , in accordance with certain aspects of the present disclosure. 
         [0148]    The graph  2300  represents Eigenvalues  2309  from 0 to −30 dB. The graph  2300  represents frequency range from 4500 to 6500 MHz. A process for calculating Eigenvalues  2309  versus frequency  2310  from radiation patterns for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 23  illustrates acceptable performance for Eigenvalues  2309  versus frequency  2310  for the antenna array configuration  1604 . 
         [0149]    The graph  2300  illustrates eight traces  2312 , wherein each trace corresponds to Eigenvalues  2309  versus frequency  2310  among the antennas  1606 - 1613 . The first trace  1601  is normalized to 0 dB. In particular, traces  2301 ,  2302 ,  2303 ,  2304 ,  2305 ,  2306 ,  2307 , and  2308  are sorted according to their magnitude. 
         [0150]    4. PCMCIA Card Having a PCB with Six Chip Antennas and Two PIFAs. 
         [0151]      FIG. 24  illustrates an example of a prototype PCMCIA card  2400  employing an antenna array configuration  2404  having six (6) ceramic chip antennas  2406 - 2411  and two (2) planar inverted F antennas (PIFA)  2412 - 2413  for use with the system  100 , as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure.  FIG. 25  illustrates an example of a magnified view  2500  of a top end of the PCMCIA card  2400 , as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. The PCMCIA card  2400  may be of the type that connects to other electronic devices, such as a laptop computer, to provide the electronic device with radio frequency (RF) wireless communication capability. 
         [0152]    The PCMCIA card  2400  generally includes a printed circuit board  2402 , a ground plane  2414 , six (6) ceramic chip antennas  2406 - 2411  (also labeled  1 - 6 , respectively) and two (2) planar inverted F antennas (PIFA)  2412 - 2413  (also labeled  7 - 8 , respectively), wherein all eight antennas together form the antenna array  2404 . Also illustrated in  FIGS. 24-25  are eight (8) electrically conductive paths  2415 - 2422  and eight (8) eight connectors  2423 - 2430 . 
         [0153]    The PCB  2402  may have a width dimension  2432  of 50 mm and a length dimension  2434  of 125 mm. The ground plane  2414  may have a width dimension  2433  of 50 mm and a length dimension  2458  of 121 mm. The ground plane  2414  may be centered within a distal end surface of the PCB  2402  permitting a non-grounded border portion of the PCB to have a left border dimension  2438  of 4 mm, a top border dimension  2442  of 4 mm, and a right border dimension  2440  of 4 mm. The antenna array  2404 , located at the distal end of the PCB  2402  has a length dimension  2436  of about 30 mm. In  FIG. 24 , each ceramic chip antenna  2406 - 2411  has a width dimension  2444  of 2 mm, a length dimension  2446  of 4 mm, and a height dimension of 0.8 mm. In  FIG. 4 , a separation distance  2448  between each ceramic antenna  2406 - 2411  is about 15 mm, corresponding to approximately ¼ wavelength. The two PIFAs  2412 - 2413  are located a height dimension of 4 mm above the ground plane  2414 . Each of the PIFAs  2412 - 2413  has a length dimension  2452  of 9 mm and a width dimension  2450  of 9 mm. Adjacent PIFAs may be separated by a separation distance  2451  of 15 mm. Other dimensions or features, such as these described as well as other features, shown in  FIGS. 24-25 , may be permitted within the scope of the present invention. 
         [0154]    Ceramic chip antennas may be formed in a variety of ways and may have a variety of shapes, which are primarily rectangular. Ceramic chip antennas advantageously provide a small surface area for mounting on a PCB and recently have been improved to provide wider bandwidth and higher efficiency. Examples of ceramic chip antennas that may be used with the present invention include those made by Taiyo Yuden Co., Ltd., including, for example, part number AH 316M245001 (3.2 L×1.6 W×0.5 mm T), 2.4 GHz chip antenna, made for use in Bluetooth® and wireless LAN applications in mobile phones and other mobile devices. Examples of antenna structures employed within a ceramic chip package include monopole and wire inverted F antenna (WIFA). For example, WIFAs are shown in  FIGS. 24 ,  25 ,  31 , and  32 . Other ceramic chip antennas from other manufacturers, in various sizes, having various frequency ranges, and having various performance characteristics may also be used within the scope of the present invention. 
         [0155]    Individually, various design and engineering details for prototype and production versions of each of the printed circuit board  2402  (e.g. FR4), the ground plane  2414 , the six (6) ceramic chip antennas  2406 - 2411 , the two (2) planar inverted F antennas (PIFA)  2412 - 2413 , the eight electrically conductive paths  2415 - 2422 , and eight (8) eight connectors  2423 - 2430 , are well known to those skilled in the art of those individual elements. 
         [0156]    The PCMCIA card  2400  has two chip antennas  2406 - 2407  located along a left side of the card  2400 , two chip antennas  2408 - 2409  located along a top of the card  2400 , two chip antennas  2410 - 2411  located along a right side of the card  2400 , and the two PIFAs  2412 - 2413  located above top of a surface of the ground plane  2414  on the PCB  2402 , and between and somewhat below the chip antennas  2406  and  2411 . Other configurations of the antenna array  2404  are possible and may be used within the scope of the present invention. 
         [0157]    The antenna array  2404 , illustrated in  FIGS. 24-25 , advantageously permits the PCMCIA card  2400 , having dimensions compatible with industry standard dimensions (e.g., length and width), to be adapted for use in an 8×8 MIMO communication system  100 . The antenna array  2404 , 8×8 for example, is small enough to fit on a distal end of the PCMCIA card  2400  while provide an acceptable antenna radiation pattern, and other acceptable communications characteristics, as further described in  FIGS. 26-30 . 
         [0158]      FIG. 26  illustrates an example of a graph  2600  of efficiency loss  2609  versus frequency  2610  for the antenna array configuration  2404 , as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
         [0159]    The graph  2600  represents efficiency loss  2609  from 0 to −10 dB. The graph  2600  represents frequency range from 4700 to 6000 MHz. A process for measuring efficiency loss  2609  versus frequency  2610  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 26  illustrates acceptable performance for efficiency loss  2609  versus frequency  2610  for the antenna array configuration  2404 . 
         [0160]    The graph  2600  illustrates eight traces  2612 , wherein each trace  2601 - 2608  corresponds to an efficiency loss  2609  versus frequency  2610  for one the antennas  2406 - 2413 . In particular, traces  2601 ,  2602 ,  2603 ,  2604 ,  2605 ,  2606 ,  2607 , and  2608  correspond to antennas  2406  through  2413 , respectively. 
         [0161]    The data illustrated in the graph  2600  includes electrical loss of about 0.2 to 0.3 dB in each of the paths  2415 - 2422 , which are constructed as coaxial cables in the prototype version of the PCMCIA card  2400 . Such electrical loss may not be present in production version of the PCMCIA card  2400 , wherein PCB traces on the PCB  2402  are used to provide the paths  2415 - 2422 . Therefore, the efficiency loss  2609  for each antenna  2406 - 2413  versus frequency  2610  may improve in the graph  2600  by about 0.2 to 0.3 dB in a production version of the PCMCIA card  2600 . 
         [0162]      FIG. 27  illustrates an example of a graph  2700  of S-parameters (e.g., return loss and isolation)  2709  versus frequency  2710  for two adjacent antennas in the antenna array configuration  2404 , as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
         [0163]    The graph  2700  represents the S-parameters  2709  from 0 to −35 dB. The graph  2700  represents frequency range from 4000 to 6200 MHz. A process for measuring S-parameters  2709  versus frequency  2710  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 2700  illustrates acceptable performance for S-parameters  2709  versus frequency  2710  for the antenna array configuration  2404 . 
         [0164]    The graph  2700  illustrates three traces  2712 , wherein each trace  2704 ,  2706 , and  2708  corresponds to S-parameters  2709  versus frequency  2710  for two adjacent antennas  2406 - 2408 . In particular, traces  2704  and  2706  correspond to return loss  2709  versus frequency  2710  for the two adjacent antennas  2407  and  2408  (i.e., around the corner of the PCB), respectively. Trace  2702  represents isolation  2709  versus frequency  2710  between the two adjacent antennas  2407  and  2408 . As shown in  FIG. 27 , antennas  2407  and  2408  provide the worst isolation. 
         [0165]      FIG. 28  illustrates an example of a graph  2800  of S parameters  2809  versus frequency  2810  providing a measure of return loss and isolation for the antenna array configuration  2404 , as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
         [0166]    The graph  2800  represents S parameters  2809  from 0 to −35 dB. The graph  2800  represents frequency range from 4000 to 6200 MHz. A process for measuring S parameters  2809  versus frequency  2810  for an antenna array  2800  is well known to those skilled in the art of antenna array designs.  FIG. 2800  illustrates acceptable performance for S parameters  2809  versus frequency  2810  for the antenna array configuration  2404 . 
         [0167]    The graph  2800  illustrates three traces  2812 , wherein each trace  2802 ,  2804 , and  2806  corresponds to S parameters  2809  versus frequency  2810  for two adjacent antennas  2412  and  2413 . In particular, traces  2804  and  2806  correspond to return loss  2809  versus frequency  2810  for the two adjacent antennas  2412  and  2413 , respectively. Trace  2802  represents isolation  2809  versus frequency  2810  between the two adjacent antennas  2412  and  2413 . As shown in  FIG. 28 , PIFAs  2412  and  2413  provide the largest return loss bandwidth. 
         [0168]      FIG. 29  illustrates an example of a graph  2900  of correlation coefficient  2909  versus frequency  2910  for the antenna array configuration  2404 , as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
         [0169]    The graph  2900  represents correlation coefficients  2909  from 0 to 1. The graph  2900  represents frequency range from 4700 to 6000 MHz. A process for measuring correlation coefficients  2909  versus frequency  2910  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 29  illustrates acceptable performance for correlation coefficients  2909  versus frequency  2910  for the antenna array configuration  2404 . 
         [0170]    The graph  2900  illustrates 28 traces  2912 , wherein each trace corresponds to correlation coefficients  2909  versus frequency  2910  among the antennas  2406 - 2413 . For example, one trace represents correlation coefficients  2909  versus frequency  2910  between antennas  2406  and  2407 , another represents correlation coefficients  2909  versus frequency  2910  between antennas  2406  and  2408 , and so forth. 
         [0171]      FIG. 30  illustrates an example of a graph  3000  of Eigenvalues  3009  of the covariance matrix versus frequency  3010  for the antenna array configuration  2404 , as shown in  FIG. 24 , in accordance with certain aspects of the present disclosure. 
         [0172]    The graph  3000  represents Eigenvalues  3009  from 0 to −30 dB. The graph  3000  represents frequency range from 4700 to 5800 MHz. A process for calculating Eigenvalues  3009  versus frequency  3010  from radiation patterns for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 30  illustrates acceptable performance for Eigenvalues  3009  versus frequency  3010  for the antenna array configuration  2404 . 
         [0173]    The graph  3000  illustrates eight traces  3012 , wherein each trace corresponds to Eigenvalues  3009  versus frequency  3010  among the antennas  2406 - 2413 . The first trace  3001  is normalized to 0 dB. In particular, traces  3001 ,  3002 ,  3003 ,  3004 ,  3005 ,  3006 ,  3007 , and  3008  are sorted according to their magnitude. 
         [0174]    5. Laptop Having a PCB with Sixteen Chip Antennas. 
         [0175]      FIG. 31  illustrates an example of a laptop  3100  employing a printed circuit board (PCB)  3122  employing sixteen (16) ceramic chip antennas  3106 - 3121  for use with the system  100 , as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure.  FIG. 32  illustrates a magnified view  3200  of top right corner of the example shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. The laptop  3100  may be of the type having two housings hinged together, wherein the first housing carries a display and the PCB  3122 , and the second housing  3101  carries elements of a computer including the keyboard. The sixteen (16) ceramic chip antennas  3106 - 3121  are advantageously carried by the first housing to provide for quality communications when the first housing is in an open position (e.g., greater than 90 degrees) relative to the second housing. 
         [0176]    The laptop  3100  generally includes a printed circuit board  3122 , a ground plane  3124 , and sixteen (16) ceramic chip antennas  3106 - 3121  (also labeled  1 - 16 , respectively) forming an antenna array  3104 . Also illustrated in  FIG. 31  are sixteen (16) electrically conductive paths  3126 - 3131  and sixteen (16) connectors  3136 - 3151 . 
         [0177]    The PCB  3122  may have a width dimension  3132  of 254 mm and a length dimension  3134  of 250 mm. The ground plane  3124  may have a width dimension  3133  of 222 mm and a length dimension  3158  of 186 mm. The ground plane  3124  may be centered within a distal end surface of the PCB  3122  permitting a non-grounded border portion of the PCB to have a left border dimension  3160  of 4 mm, a top border dimension  3164  of 4 mm, and a right border dimension  3162  of 4 mm. In  FIGS. 31 and 32 , each ceramic chip antenna  3106 - 3121  has a width dimension of 2 mm, a length dimension of 4 mm, and a height dimension of 0.8 mm. In  FIG. 32 , a separation distance  3148  between each ceramic antenna  3106 - 3121  is about 15 mm, corresponding to one quarter wavelength. Other dimensions or features, such as these described as well as other features, shown in  FIGS. 31 and 32 , may be permitted within the scope of the present invention. The ceramic chip antennas may be the same or similar to those described with reference to  FIGS. 24-25 . 
         [0178]    Individually, various design and engineering details for prototype and production versions of each of the printed circuit board  3122  (e.g. FR4), the ground plane  3124 , the sixteen (16) ceramic chip antennas  3106 - 3121 , the sixteen (16) electrically conductive paths  3126 - 3131  and sixteen (16) connectors  3136 - 3151 , are well known to those skilled in the art of those individual elements. 
         [0179]    The laptop  3100  has eight chip antennas  3106 - 3113  located along a top side and near a top right corner of the PCB  3122 , and eight chip antennas  3114 - 3121  located along a right side and near a top right corner of the PCB  3122 . Other configurations of the antenna array  3104  are possible and may be used within the scope of the present invention. 
         [0180]    The antenna array  3104 , illustrated in  FIGS. 31 and 32 , advantageously permits the laptop  3100 , having dimensions compatible with industry standard or manufactured dimensions (e.g., length and width), to be adapted for use in a 16×16 MIMO communication system  100 . The antenna array  3104 , 16×16 for example, is small enough to fit at top right corner of the PCB  3122  while provide an acceptable antenna radiation pattern, and other acceptable communications characteristics, as further described in  FIGS. 33-41 . 
         [0181]      FIG. 33  illustrates an example of a graph  3300  of efficiency loss  3309  versus frequency  3310  for the antenna array configuration, as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
         [0182]    The graph  3300  represents efficiency loss  3309  from 0 to −10 dB. The graph  3300  represents frequency range from 4700 to 6000 MHz. A process for measuring efficiency loss  3309  versus frequency  3310  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 33  illustrates acceptable performance for efficiency loss  3309  versus frequency  3310  for the antenna array configuration  3104 . 
         [0183]    The graph  3300  illustrates sixteen traces  3312 , wherein each trace (not numbered) corresponds to an efficiency loss  3309  versus frequency  3310  for one of the antennas  3106 - 3121 . 
         [0184]    The data illustrated in the graph  3300  includes electrical loss of about 1.3 dB in each of the paths  3126 - 3131 , which are constructed as coaxial cables in the prototype version of the PCB  3122 . Such electrical loss may not be present in production version of the PCB  3122 , wherein PCB traces on the PCB  3122  are used to provide the paths  3126 - 3131 . Therefore, the efficiency loss  3309  versus frequency  3310  for each antenna  3306 - 3321  may improve in the graph  3300  by about 1.3 dB in a production version of the PCB  3300 . 
         [0185]      FIG. 34  illustrates an example of a graph  3400  of S-parameters  3409  versus frequency  3410  for two adjacent antennas in the antenna array configuration  3104 , as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
         [0186]    The graph  3400  represents S-parameters  3409  (e.g., return loss and isolation) from 0 to −35 dB. The graph  3400  represents frequency range from 4000 to 6200 MHz. A process for measuring S-parameters  3409  versus frequency  3410  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 3400  illustrates acceptable performance for S-parameters  3409  versus frequency  3410  for the antenna array configuration  3104 . 
         [0187]    The graph  3400  illustrates three traces  3412 , wherein each trace  3401 - 3403  corresponds to S-parameters  3409  versus frequency  3410  for two adjacent antennas. In particular, traces  3402  and  3403  correspond to return loss  3409  versus frequency  3410  between two adjacent antennas  3106  and  3107 , respectively. Trace  3401  represents isolation  3409  versus frequency  3410  between the two adjacent antennas  3106  and  3107 . 
         [0188]      FIG. 35  illustrates an example of a graph  3500  of S parameters  3509  versus frequency  3510  for the antenna array configuration  3104 , as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
         [0189]    The graph  3500  represents S-parameters  3509  from 0 to −35 dB. The graph  3500  represents frequency range from 4000 to 6200 MHz. A process for measuring S-parameters  3509  versus frequency  3510  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 3500  illustrates acceptable performance for S-parameters  3509  versus frequency  3510  for the antenna array configuration  3504 . 
         [0190]    The graph  3500  illustrates three traces  3512 , wherein each trace  3501 - 3503  corresponds to S-parameters  2809  versus frequency  2810  for two adjacent antennas. In particular, traces  3502  and  3503  correspond to return loss  3509  versus frequency  3510  between two adjacent antennas  3113  and  3114 , respectively. Trace  3501  represents isolation  3509  versus frequency  3510  between the two adjacent antennas  3113  and  3114 . 
         [0191]      FIG. 36  illustrates an example of a graph  3600  of correlation coefficient  3609  versus frequency  3610  for the antenna array configuration  3104 , as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
         [0192]    The graph  3600  represents correlation coefficients  3609  from 0 to 1. The graph  3600  represents frequency range from 4700 to 6000 MHz. A process for measuring correlation coefficients  3609  versus frequency  3610  for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 36  illustrates acceptable performance for correlation coefficients  3609  versus frequency  3610  for the antenna array configuration  3104 . 
         [0193]    The graph  3600  illustrates 120 traces  3612 , wherein each trace corresponds to correlation coefficients  3609  versus frequency  3610  among the antennas  3106 - 3121 . For example, one trace represents correlation coefficients  3609  versus frequency  3610  between antennas  3606  and  3607 , another represents correlation coefficients  3609  versus frequency  3610  between antennas  3606  and  3608 , and so forth. 
         [0194]      FIG. 37  illustrates an example of a graph  3700  of Eigenvalues  3709  of the covariance matrix versus frequency  3710  for the antenna array configuration  3104 , as shown in  FIG. 31 , in accordance with certain aspects of the present disclosure. 
         [0195]    The graph  3700  represents Eigenvalues  3709  from 0 to −30 dB. The graph  3700  represents frequency range from 4700 to 6000 MHz. A process for calculating Eigenvalues  3709  versus frequency  3710  from radiation patterns for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 37  illustrates acceptable performance for Eigenvalues  3709  versus frequency  3710  for the antenna array configuration  3104 . 
         [0196]    The graph  3700  illustrates sixteen traces  3712 , wherein each trace corresponds to Eigenvalues  3709  versus frequency  3710  sorted according to their magnitude. The first trace is normalized to 0 dB. 
         [0197]      FIG. 38  illustrates an example of a graph  3800  of Eigenvalues  3809  versus frequency  3810  for eight chip antennas  3106 - 3113  (also numbered antennas  1 - 8 ) across the top of the antenna array configuration  3104 , as shown in  FIG. 31 , and as shown schematically as  3814  in  FIG. 38 , in accordance with certain aspects of the present disclosure. 
         [0198]    The graph  3800  represents Eigenvalues  3809  from 0 to −30 dB. The graph  3800  represents frequency range from 4700 to 6000 MHz. A process for calculating Eigenvalues  3809  versus frequency  3810  from radiation patterns for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 38  illustrates acceptable performance for Eigenvalues  3809  versus frequency  3810  for the antenna array configuration  3104 . 
         [0199]    The graph  3800  illustrates eight traces  3812 , wherein each trace corresponds to Eigenvalues  3809  versus frequency  3810  among the antennas  3106 - 3113 . The first trace  3801  is normalized to 0 dB. 
         [0200]      FIG. 39  illustrates an example of a graph  3900  of Eigenvalues  3909  versus frequency  3910  for eight chip antennas  3114 - 3121  (also numbered antennas  9 - 16 ) across the right side of the antenna array configuration  3104 , as shown in  FIG. 31 , and as shown schematically as  3914  in  FIG. 38 , in accordance with certain aspects of the present disclosure. 
         [0201]    The graph  3900  represents Eigenvalues  3909  from 0 to −30 dB. The graph  3900  represents frequency range from 4700 to 6000 MHz. A process for calculating Eigenvalues  3909  versus frequency  3910  from radiation patterns for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 39  illustrates acceptable performance for Eigenvalues  3909  versus frequency  3910  for the antenna array configuration  3104 . 
         [0202]    The graph  3900  illustrates eight traces  3912 , wherein each trace corresponds to Eigenvalues  3909  versus frequency  3910  among the eight chip antennas  3114 - 3121 . The first trace  3901  is normalized to 0 dB. 
         [0203]      FIG. 40  illustrates an example of a graph  4000  of Eigenvalues  4009  versus frequency  4010  for eight chip antennas  3110 - 3127  (also numbered antennas  5 - 12 ) around the right top corner of the antenna array configuration  3104 , as shown in  FIG. 31 , and as shown schematically as  4014  in  FIG. 40 , in accordance with certain aspects of the present disclosure. 
         [0204]    The graph  4000  represents Eigenvalues  4009  from 0 to −30 dB. The graph  4000  represents frequency range from 4700 to 6000 MHz. A process for calculating Eigenvalues  4009  versus frequency  4010  from radiation patterns for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 40  illustrates acceptable performance for Eigenvalues  4009  versus frequency  4010  for the antenna array configuration  3104 . 
         [0205]    The graph  4000  illustrates eight traces  4012 , wherein each trace corresponds to Eigenvalues  4009  versus frequency  4010  among the eight chip antennas  3110 - 3127 . The first trace  4001  is normalized to 0 dB. 
         [0206]      FIG. 41  illustrates an example of a graph  4100  of Eigenvalues  4109  versus frequency  4110  for eight odd numbered position chip antennas  3106 ,  3108 ,  3110 ,  3112 ,  3114 ,  3116 ,  3118 , and  3120  (also numbered antennas  1 ,  3 ,  5 ,  7 ,  9 ,  11 ,  13 , and  15 ) across the top and right side of the antenna array configuration  3104 , as shown in  FIG. 31 , and as shown schematically as  3914  in  FIG. 38 , in accordance with certain aspects of the present disclosure. The separation between two measured antennas (i.e., two antennas separated by only one other antenna) is one half wavelength. 
         [0207]    The graph  4100  represents Eigenvalues  4109  from 0 to −30 dB. The graph  4100  represents frequency range from 4700 to 6000 MHz. A process for calculating Eigenvalues  4109  versus frequency  4110  from radiation patterns for an antenna array is well known to those skilled in the art of antenna array designs.  FIG. 41  illustrates acceptable performance for Eigenvalues  4109  versus frequency  4110  for the antenna array configuration  3104 . 
         [0208]    The graph  4100  illustrates eight traces  4112 , wherein each trace corresponds to Eigenvalues  4109  versus frequency  4110  among the eight chip antennas  3106 ,  3108 ,  3110 ,  3112 ,  3114 ,  3116 ,  3118 , and  3120 . The first trace  3106  is normalized to 0 dB. 
         [0209]    6. Laptop Having a PCB with Eight Monopole Antennas. 
         [0210]      FIG. 42  illustrates an example of a laptop  4200  employing a printed circuit board (PCB)  4202  employing eight (8) printed monopole antennas  4206 - 4213  for use with the system  100 , as shown in  FIGS. 1 and 2 , in accordance with certain aspects of the present disclosure.  FIG. 43  illustrates a magnified view  4300  of top right corner of the example shown in  FIG. 42 , in accordance with certain aspects of the present disclosure. The laptop  4200  may be of the type having two housings hinged together, as shown in  FIGS. 31 and 32 . The eight (8) printed monopole antennas  4206 - 4213  are advantageously carried by the first housing to provide for quality communications when the first housing (e.g., also carrying a 13 inch display) is in an open position (e.g., greater than 90 degrees) relative to the second housing. 
         [0211]    The laptop  4200  generally includes a printed circuit board  4202 , a ground plane  4204 , and eight (8) printed monopole antennas  4206 - 4213  (also labeled  1 - 8 , respectively) forming an antenna array  4204 . Also illustrated in  FIG. 42  are eight (8) electrically conductive paths  4215 - 4222 , and eight (8) connectors  4223 - 4230 . 
         [0212]    The PCB  4202  may have a width dimension  4232  of 255 mm and a length dimension  4234  of 210 mm. The PCB  4202  may extend beyond the ground plane  3124  at the top right corner of the PCB  4202  permitting a non-grounded border portion of the PCB to have a right border dimension  4264  of 5 mm and a top border dimension  4266  of 5 mm. In  FIGS. 42 and 43 , each printed monopole antenna  4202 - 4213  has characteristics, as described above with reference to  FIGS. 3 ,  4 ,  8 - 10 , and  16 - 18 . Other dimensions or features, such as these described as well as other features, shown in  FIGS. 41 and 42 , may be permitted within the scope of the present invention. 
         [0213]    Individually, various design and engineering details for prototype and production versions of each of the printed circuit board  4202  (e.g. FR4), the ground plane  4204 , the eight (8) printed monopole antennas  4206 - 4213 , the eight (8) electrically conductive paths  4215 - 4222 , and the eight (8) connectors  4223 - 4230 , are well known to those skilled in the art of those individual elements. 
         [0214]    The laptop  4200  has four (4) printed monopole antennas  4206 - 4209  located along a top side and near a top right corner of the PCB  4202 , and four (4) printed monopole antennas  4210 - 4213  located along a right side and near a top right corner of the PCB  4202 . Other configurations of the antenna array  4204  are possible and may be used within the scope of the present invention. 
         [0215]    The antenna array  4204 , illustrated in  FIGS. 41 and 42 , advantageously permits the laptop  4200 , having dimensions compatible with industry standard or manufactured dimensions (e.g., length and width), to be adapted for use in a 8×8 MIMO communication system  100 . The antenna array  4204 , 8×8 for example, is small enough to fit at top right corner of the PCB  4202  while provide an acceptable antenna radiation pattern, and other acceptable communications characteristics, which are not shown in graphs, but are similar to the characteristics of other printed monopole antenna designs described herein. 
         [0216]    Fitting of high order antenna arrays into mobile and portable handheld devices, such as cellular phones and smart phones may be a challenging task because of their size. However, the techniques presented herein may allow for compact arrays that may be incorporated into such devices to increase data throughput for applications running on such devices. 
         [0217]    Very high data rate wireless communication systems may be utilized for the transmission of high definition (HD) video signals. By exploiting the size of HD devices, such as widescreen HD television sets, one or more high order antenna arrays (e.g., with eight or sixteen elements) may be incorporated into such devices and spaced out accordingly in order to improve the spatial diversity and decrease the correlation between antenna pairs. 
         [0218]    The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. 
         [0219]    The description and drawings are illustrative of aspects and examples of the invention and are not to be construed as limiting the invention. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. 
         [0220]    Numerous specific details are described to provide a thorough understanding of the present invention. However, in certain instances, well-known or conventional details are not described in order to avoid obscuring the description of the present invention. References to one embodiment or an embodiment in the present disclosure are not necessarily to the same embodiment, and such references may include one or more embodiments. 
         [0221]    In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will be evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.