Patent Publication Number: US-11044025-B1

Title: Characterizing antenna patterns

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority benefit of the United States Provisional Patent Application titled, “CHARACTERIZING ANTENNA PATTERNS,” filed on Dec. 28, 2016 and having Ser. No. 15/392,937. The subject matter of this related application is hereby incorporated herein by reference. 
     TECHNICAL FIELD 
     This disclosure generally relates to characterizing antenna patterns. 
     BACKGROUND 
     Antennas on aircraft are used for wireless communication with other aerial or ground vehicles and stationary structures. To provide communication and connectivity services, antennas emit or radiate antenna signals. The radiated signals may be referred to as an antenna pattern. Aircraft antennas have complex antenna patterns that arise from scattering and diffraction from the aircraft itself and mounted components on the aircraft. An antenna pattern is the relative power density (measured in dB) of the wave transmitted by an antenna in a given direction. Antenna patterns on aircraft are rarely uniform or spherical. Usually they are complex, with different peaks and nulls. Characterizing antenna patterns using an antenna measurement system may be helpful in increasing the size and strength of wireless connections. An antenna measurement system typically consists of transceivers, probes, an inertial measurement unit (IMU), altimeter, and GPS/GLASS. 
     SUMMARY OF PARTICULAR EMBODIMENTS 
     In particular embodiments, an antenna measurement system may measure and characterize an unknown antenna pattern produced by an antenna on an aircraft. The antenna and aircraft combination may be referred to as a device under test (DUT). The antenna measurement system may be mounted onto a vehicle, which may be an airborne vehicle (e.g., N-copter) or a ground vehicle (e.g., self-driving car), or a stationary installation (e.g., base station). The antenna measurement system may include one or more antennas mounted at various locations on the vehicle, along with one or more gimbals to steer the antenna and one or more pieces of signal-absorbing foam to absorb extraneous signals. The antennas may be orthogonal probes with phase measurement ability, which may enable the antenna measurement system to characterize linear, circular, and elliptically polarized antenna patterns. The antenna measurement system may further include location and orientation measurement components, including IMU units, GPS, and an altimeter, among other components. The antenna measurement system may travel around the DUT while the DUT produces an unknown antenna pattern. The antenna measurement system may measure and record the signal received from the DUT. Using the location and orientation data obtained from the measurement components, the antenna measurement system may combine the measured DUT data and the location and orientation data to produce an accurate characterization of the antenna pattern produced by the DUT. The above may be accomplished by implementing the following process: determine a received power at a receiving antenna mounted to an antenna measurement system from a transmitting antenna mounted to a device under test (DUT) in motion relative to the antenna measurement system; determine one or more first orientation parameters of the antenna measurement system; determine one or more second orientation parameters of the DUT; and determine an antenna pattern of the transmitting antenna based on the received power, the first orientation parameters, and the second orientation parameters. In particular embodiments, the above process may be implemented with a receiving antenna mounted on the DUT as well as a transmitting antenna mounted on the DUT. 
     The embodiments disclosed above are only examples, and the scope of this disclosure is not limited to them. Particular embodiments may include all, some, or none of the components, elements, features, functions, operations, or steps of the embodiments disclosed above. Embodiments according to the invention are in particular disclosed in the attached claims directed to a method, a storage medium, a system and a computer program product, wherein any feature mentioned in one claim category, e.g. method, can be claimed in another claim category, e.g. system, as well. The dependencies or references back in the attached claims are chosen for formal reasons only. However any subject matter resulting from a deliberate reference back to any previous claims (in particular multiple dependencies) can be claimed as well, so that any combination of claims and the features thereof are disclosed and can be claimed regardless of the dependencies chosen in the attached claims. The subject-matter which can be claimed comprises not only the combinations of features as set out in the attached claims but also any other combination of features in the claims, wherein each feature mentioned in the claims can be combined with any other feature or combination of other features in the claims. Furthermore, any of the embodiments and features described or depicted herein can be claimed in a separate claim and/or in any combination with any embodiment or feature described or depicted herein or with any of the features of the attached claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example aircraft with an example antenna unit. 
         FIG. 2  illustrates an example aircraft with example antenna patterns. 
         FIG. 3  illustrates an example antenna measurement system. 
         FIG. 4  illustrates antenna measurement system arrangement between an example antenna measurement system and an example aircraft. 
         FIG. 5  illustrates an example antenna measurement system arrangement between one or more example antenna measurement systems and an example aircraft. 
         FIG. 6  illustrates an example method for characterizing an antenna pattern. 
         FIG. 7  illustrates an example computer system. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
       FIG. 1  illustrates an example aircraft  100  with an example antenna  120 . Aircraft  100  may be manned or unmanned and may operate under human control or autonomously. Aircraft  100  may comprise mounted components  110 , such as propellers, engines, flaps, ailerons, winglets, a fuselage, tail components, and other suitable components. Aircraft  100  may also comprise an antenna  120 . Antenna  120  may emit signals  121  in one or more directions. Some signals  121  may reflect off of or be diffracted by the mounted components on the aircraft. This may affect the antenna signals  121  that are emitted or received from the antenna  121 , such signals  121  may not emanate from antenna  120  in straight lines. This may result in antenna  120  producing an antenna pattern  120  that is not spherical, symmetrical, or predictable. The combination of aircraft  100  and antenna  120  may be referred to collectively as a device under test (DUT). 
       FIG. 2  illustrates an example aircraft  100  and two example antenna patterns  210  and  220 . Antenna pattern  210  may represent an idealized antenna pattern, or an antenna pattern generated under idealized conditions. Antenna pattern  210  may be unaffected by mounted components  110  or other atmospheric conditions. Despite every feasible optimization, antenna pattern  210  may not be possible to achieve in the real world. Instead, a real-world antenna pattern may look like antenna pattern  220 . Antenna pattern  220  may be an antenna pattern that is affected by aircraft  100  and all its mounted components, including propellers, engines, flaps, ailerons, winglets, a fuselage, tail components, and other suitable components. Antenna pattern  220  may be further affected by atmospheric elements (e.g., air pressure, wind patterns, precipitation, electric fields produced by the earth or storm clouds). Antenna pattern  220  may be an antenna pattern that is typically generated by an antenna on an aircraft. Antenna pattern  220  may be much more complex than the ideal spherical antenna pattern that is represented by antenna pattern  210 . Characterizing antenna pattern  220  may be beneficial in increasing the size and strength of wireless connections. As an example and not by way of limitation, knowing the peaks and nulls of antenna pattern  220  may allow an administrator to optimize communications for the particular pattern of antenna pattern  220 . 
     Many techniques exist to measure antenna patterns, including near-field and far-field range measurements, polar planar scanning, bi-polar planar scanning, cylindrical near-field range, and spherical near-field range. Traditional measurement systems, such as aircraft-scale anechoic chambers and outdoor mobile gantry systems are large, costly, and impractical to send to remote locations. An antenna measurement system typically consists of transceivers, probes, an inertial measurement unit (IMU), altimeter, and GPS/GNSS. Mounting these components on an aerial or ground vehicle, or on a stationary location, would enable measurement of aircraft antenna patterns while overcoming the aforementioned limitations. 
       FIG. 3  illustrates an example antenna measurement system  300  comprising at least some of the components discussed above. Antenna measurement system  300  may comprise vehicle  310 , gimbal  331 , signal-absorbing foam  332 , and one or more antennas  333 . Vehicle  310  may be an aerial or ground vehicle, or may be a stationary mount, which may be referred to as a base station. In the particular example given by  FIG. 3 , antenna measurement system  300  is mounted to an N-copter (e.g., octocopter), but antenna measurement system  300  may alternatively be mounted to a ground vehicle or to a base station that does not move. Gimbal  331  may rotate in all directions such that antenna  333  may be directed in any direction. This may enable full spherical coverage of the area surrounding antenna measurement system  300 . Both top and bottom of vehicle  310  may comprise gimbal  331  for steering antenna  333 , signal-absorbing foam  332  for preventing signals from reflecting off vehicle  310  and interfering with the accuracy of the measurements, and one or more antennas  333 . 
     In particular embodiments, antenna measurement system  300  may have one or more antennas  333  and need not be limited to two antennas. Antennas  333  may be any suitable antenna, such as orthogonal probe antennas, continuous wave antennas, orthogonal linearly polarized antennas, or orthogonally-fed aperture antennas (e.g., a dual-feed horn). In particular embodiments, antennas  333  of antenna measurement system  300  may be probe antennas which act as transmitters or receivers, or both. In particular embodiments, antenna  120  on aircraft  100  may be a probe antenna which may act as a transmitter or a receiver, or both. A probe antenna may be used to evaluate the extraneous signals that exist in the area surrounding a DUT due to reflections and other transmitting sources. In particular embodiments, antennas  333  may comprise orthogonal probes that may be operable to measure polarized signals. Two orthogonal linearly polarized antennas may enable measurement of linear polarized antenna signals regardless of the orientation of either antennas  333  or aircraft  100 . Thus, antennas  333 , as orthogonal probe antennas comprising phase measurement ability, may enable antenna measurement system  300  to characterize linear, circular, and elliptically polarized patterns. Probe antennas may be considered to be orthogonal if they produce orthogonal signals. Two signals are orthogonal if their inner product is zero. Mathematically, the inner product of signals g(x) and f(x) may be defined as &lt;g(x), f(x)&gt;=∫ −∞   ∞ (g*(x)f(x))dx where g*(x) is the complex conjugate of g(x). If &lt;g(x),f(x)&gt;=0, then g(x) is orthogonal to f(x). In particular embodiments, orthogonal probe antennas may be linearly polarized, circularly polarized, or elliptically polarized, or any combination of the three. This may enable antennas  333  to completely characterize an unknown antenna pattern (e.g., the antenna pattern produced by antenna  120  of aircraft  100 ). In order to completely characterize the radiation pattern of antenna  120 , both the magnitude of the power received from antenna  120  and the phase of the signal produced by antenna  120  are required. These measurements may be specified in two orthogonal directions so that all components of the antenna signal may be captured. As an example and not by way of limitation, antenna  120  may transmit a signal having frequency f. Antenna measurement system  300  may measure an antenna pattern traveling in the y direction at a particular point as E={circumflex over (x)}Ae jD e j2πft +{circumflex over (z)}Be jF e j2πft , where A is the magnitude of the x component of the antenna pattern, B is the magnitude of the y component of the antenna pattern, D is the phase of the x component of the antenna pattern, and F is the phase of the z component of the antenna pattern. If D=F, the polarization of the antenna pattern is linear. If D and F are separated by 90 degrees, the antenna pattern may be circularly polarized. The antenna patterns produced by antenna  120  may be orthogonal to the direction of travel in the far field region (e.g., far away from antenna  120 ). Determining the polarization relationship between the antenna pattern emitted of antenna measurement system  300  and the unknown antenna pattern of antenna  120  on aircraft  100  may enable the characterization of linear, circular, and elliptically polarized antenna patterns. This may enable the accurate characterization of the unknown antenna pattern produced by antenna  120 . Although this disclosure discusses providing antenna measurement equipment in a particular manner, this disclosure contemplates providing antenna measurement equipment in any suitable manner. 
     In particular embodiments, vehicle  310 , with mounted antenna measurement system  300 , may travel around aircraft  100  and sample the received power, or may transmit a predetermined signal to test the transmit and receive performance of antenna  120  on aircraft  100 . In particular embodiments, sample points of receive power or transmit power may be determined by the required antenna pattern angular resolution. As one skilled in the art will understand, angular resolution may be the minimum angular separation at which two equal targets can be separated when at the same range. Angular resolution may be limited by the restricted aperture width of the antenna. Determining the angular resolution of both antenna  333  and antenna  120  may enable more accurate measurement of the antenna pattern produced by antenna  120 . In particular embodiments, continuous wave may be used for passive antenna measurements as well as measurement of the speed and position of aircraft  100 . A continuous wave may be an electromagnetic wave of constant amplitude and frequency. A continuous wave radar may be included as part of antenna measurement system  300 , which may be mounted to vehicle  310 , which may either be a base station or a moving vehicle. The continuous wave radar may emit a continuous wave directed at aircraft  100  and may receive an echo signal reflected back from aircraft  100 . The echo signal may provide information about the speed, shape, direction, and orientation of aircraft  100 . Although this disclosure discusses antenna measurement equipment in a particular manner, this disclosure contemplates providing antenna measurement equipment in any suitable manner. 
     Vehicle  310  may be any suitable type of vehicle, including, but not limited to an N-copter (e.g., octocopter) and ground vehicle (e.g., self-driving car, manned vehicle). In particular embodiments, vehicle  310  may be a stationary mount that is fixed to the ground (e.g., a base station). In particular embodiments, vehicle  310  may be programmed to travel around aircraft  100  at various distances while antenna measurement system  300  measures the antenna pattern produced by antenna  120 . In particular embodiments, vehicle  310  may be controlled manually, either by remote control or by a human driver physically present inside vehicle  310 . If antenna measurement system  300  is mounted to an N-copter, the N-copter may be programmed to fly around aircraft  100  while aircraft  100  is stationary (e.g., grounded), or while aircraft  100  is in flight. The N-copter may be autonomous or may be remote controlled. The N-copter may also fly around aircraft  100  while aircraft  100  is traveling at various altitudes and speeds in order to fill in the gaps in the antenna pattern measurements of antenna  120  that are not seen from other stationary locations. If antenna measurement system  300  is mounted to a ground structure (e.g., base station), antenna measurement system  300  may measure the antenna signals of antenna  120  as aircraft  100  flies past antenna measurement system  300  while it is fixed to the ground. In particular embodiments, if antenna measurement system  300  is mounted to a ground vehicle, antenna measurement system  300  may measure the antenna signals of antenna  120  as aircraft  100  is stationary (e.g., grounded) and the ground vehicle travels around aircraft  100 . In particular embodiments, antenna measurement system  300  may measure the antenna signals of antenna  120  as aircraft  100  is in flight and the ground vehicle is also in motion on the ground. In this scenario, the ground vehicle may be moving in the same direction as aircraft  100 , may be moving in the opposite direction of aircraft  100 , may be moving perpendicular to the direction of aircraft  100 , or may be moving in a zig-zag pattern along the same trajectory as the trajectory of aircraft  100 . Although this disclosure discusses providing a vehicle for an antenna measurement system in a particular manner and operating that vehicle in a particular manner, this disclosure contemplates providing and operating a vehicle for an antenna measurement system in any suitable manner. 
     Vehicle  310 , or alternatively, antenna measurement system  300 , may include additional features apart from traditional antenna probes and aerial or ground vehicles. Such features may include autopilot, a global positioning system (GPS) receiver or a global navigation satellite system (GNSS) receiver, altimeter, and one or more inertial measurement unit (IMU) systems. These components may be used to determine one or more first orientation parameters of antenna measurement system  300 . Examples of orientation parameters include, but are not limited to, the relative position of the antenna measurement system  300  in relation to aircraft  100 , path loss from antenna  333  to antenna  120 , the orientation of one or more antennas  333 , the orientation of antenna  120  or of aircraft  100 , or any other suitable parameter related to antenna measurement system  300 . An IMU is an electronic device that may measure and reports a body&#39;s specific force, angular rate, and, in particular embodiments, the magnetic field surrounding the body, and may use a combination of accelerometers and gyroscopes. An IMU may be installed in antenna measurement system  300 , on vehicle  310 , or in any other suitable location. The IMU may measure various accelerations and forces on antenna measurement system  300 , which may be used to determine an unknown antenna pattern produced by antenna  120 . The IMU may detect and record the current rate of acceleration on the antenna measurement system  300  as it is in motion (e.g., in flight or driving on the ground). The IMU may also use internal gyroscopes to detect and record changes in rotational attributes of a body in flight, such as pitch, roll, and yaw. In particular embodiments these components may be referred to as angular and linear accelerometers. Angular accelerometers may measure how the vehicle is rotating in space. There may be one or more sensors for each of three rotational axes: pitch (nose up and down), yaw (nose left and right) and roll (clockwise or counter-clockwise from the “cockpit”). Linear accelerometers may measure non-gravitational acceleration of antenna measurement system  300  in the three rotational axes: pitch, yaw, and roll. The IMU may provide data necessary for characterizing an unknown antenna pattern produced by antenna  120 . 
     In particular embodiment, antenna measurement system  300  may determine one or more second orientation parameters that are associated with the DUT (e.g., aircraft  100 ). These orientation parameters may include, but are not limited to the relative position of the antenna measurement system  300  in relation to aircraft  100 , path loss from antenna  333  to antenna  120 , the orientation of one or more antennas  120 , the orientation of aircraft  100  (e.g., roll, pitch, yaw), the altitude and velocity of aircraft  100 , the shape and makeup of aircraft  120 , or any other suitable parameter related to aircraft  100  or antenna  120 . The second orientation parameters may be determined using any suitable method, including video surveillance, CW waves as explained previously, or measurement and monitoring components installed on aircraft  100 . 
       FIG. 4  illustrates an example antenna measurement system arrangement  400  between an example antenna measurement system  300  and an example aircraft. In particular embodiments, antenna measurement system  300  may determine a received power at a receiving antenna  333  from a transmitting antenna  120  mounted to a DUT (e.g., aircraft  100 ) in motion relative to antenna measurement system  300 . As will be explained with reference to  FIG. 5 , in particular embodiments, the DUT in motion relative to the antenna measurement system may comprise: (1) the DUT (e.g., aircraft  100 ) being stationary and antenna measurement system  300  being in motion; (2) the DUT (e.g., aircraft  100 ) being in motion and antenna measurement system  300  being stationary; or (3) the DUT (e.g., aircraft  100 ) being in motion and antenna measurement system  300  being in motion, relative to each other. The term “relative to each other” may mean that the DUT and antenna measurement system  300  may not be travelling in the same direction at the same speed, because in that case they would not be in motion relative to each other. Antenna measurement system  300 , mounted to vehicle  310 , may be used to measure antenna strength of antenna  120  at various locations around aircraft  100 . In particular embodiments, this may be accomplished by flying or driving antenna measurement system  300  around stationary aircraft  100  at different distances and taking measurements of the antenna pattern. In particular embodiments, antenna measurement system  300  may be stationary and aircraft  100  may be in motion. In particular embodiments, both antenna measurement system  300  and aircraft  100  may be in motion. In particular embodiments, measurements may be taken by raster scan, or by any other suitable method for measuring antenna signals. As discussed previously, two orthogonal linearly polarized antennas enable measurement of linear polarization of an antenna pattern produced by antenna  120  regardless of the orientation of antenna  120  or aircraft  100 . Measuring the phase of the antenna pattern of antenna  120  may enable antenna measurement system  300  to determine whether the antenna pattern produced by antenna  120  is elliptically or circularly polarized. Measuring the amplitude and phase of orthogonal signals may provide vector data, and from that it may be possible to characterize various aspects of the antenna pattern produced by antenna  120  and the velocity and orientation of aircraft  100  while it is in motion. To accurately characterize an antenna pattern produced by antenna  120 , both orientation and position data about aircraft  100  (e.g., second orientation parameters) and orientation and position data about antenna measurement system  300  (e.g., first orientation parameters) must be considered. Both aircraft  100  (and, by extension, antenna  120 ) and the antenna measurement system may comprise orientation and position data provided by one or more system components (e.g., IMU, altimeter, GPS) that includes roll, pitch, yaw, altitude, latitude, longitude, and velocity, among other things. The antenna pattern produced by antenna measurement system  300  may be known, but the antenna pattern produced by antenna  120  may be unknown. By accounting for various factors, such as path loss of the known antenna pattern produced by antenna measurement system  300 , atmospheric effects (e.g., air pressure, wind patterns, precipitation, electric fields produced by the earth or storm clouds), orientation and position data, and the polarization and phase of both the known antenna pattern of antenna measurement system  300  and unknown antenna pattern of antenna  120 , it may be possible to accurately characterize the unknown antenna pattern of antenna  120 . Although this disclosure discusses measuring an unknown antenna pattern in a particular manner, this disclosure contemplates measuring an unknown antenna pattern in any suitable manner. 
     In particular embodiments, antenna measurement system  300  may determine the antenna pattern of the transmitting antenna (e.g., antenna  120 ) based on the received power from the transmitting antenna, the first orientation parameters, and the second orientation parameters. To calculate the unknown antenna pattern produced by antenna  120  using measured data (e.g., known antenna pattern on antenna measurement systems, orientation/location data, path loss, atmospheric effects and other first and second orientation parameters), the Friis transmission formula may first be used. The Friis transmission formula may produce the power received by one antenna under idealized conditions given another antenna some distance away transmitting a known amount of power. Given two antennas, the ratio of power available at the input of the receiving antenna, P r , to output power to the transmitting antenna P t , is given by: 
                 P   r       P   t       =       G   t     ⁢         G   r     ⁡     (     λ     4   ⁢   π   ⁢           ⁢   R       )       2             
where G t  and G r  are the antenna gains of the transmitting and receiving antennas, respectively, λ is the wavelength, and R is the distance between the antennas. To calculate the power at the receiving antenna in decibels, the equation becomes:
 
     
       
         
           
             
               P 
               r 
             
             = 
             
               
                 P 
                 t 
               
               + 
               
                 G 
                 t 
               
               + 
               
                 G 
                 r 
               
               + 
               
                 20 
                 ⁢ 
                 
                   
                     
                       log 
                       10 
                     
                     ⁡ 
                     
                       ( 
                       
                         λ 
                         
                           4 
                           ⁢ 
                           π 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           R 
                         
                       
                       ) 
                     
                   
                   . 
                 
               
             
           
         
       
     
     This may be is the general calculation to calculate strength of wireless links. Once this is calculated, the first and second orientation parameters may be accounted for. Thus, when the transmitting and receiving antenna patterns produced by antenna measurement system  300  is known, polarization mismatch is known, antenna gain is known, path loss is known, and receive and transmit power is known, and first and second orientation parameters are known, the unknown variable may be the antenna pattern produced by antenna  120  on aircraft  100 . Thus, with orientation data and data produced by atmospheric effects, the Friis equation may be used to accurately characterize the unknown antenna pattern of antenna  120 . Although this disclosure discusses measuring an unknown antenna pattern in a particular manner, this disclosure contemplates measuring an unknown antenna pattern in any suitable manner. 
       FIG. 5  illustrates an example antenna measurement system arrangement  500  between one or more antenna measurement systems  300  and aircraft  100 . This disclosure contemplates several different arrangements in which at least one of one or more antenna measurement systems  300  and aircraft  100  are in motion. In particular embodiments, a first arrangement may provide an aircraft  100  that may be moving and one or more antenna measurement systems  300  that may be stationary. Aircraft  100  may be flying at low altitude for testing purposes, or may be flying at normal altitudes. Antenna measurement system  300  may be a ground station antenna mounted to a base station  510 . Alternatively, the antenna measurement system may be a stationary airborne measurement system  530 . As an example and not by way of limitation, one or more antenna measurement systems  300  may be mounted onto one or more N-copters, which may hover at fixed points in the air. As aircraft  100  flies nearby this system of N-copters, antenna measurement systems  300  may measure and record data about the antenna pattern produced by antenna  120  on aircraft  100 . In particular embodiments, both a base-station-mounted antenna measurement system  300  and stationary airborne measurement systems  300  may be used at the same time, and both base-station-mounted antenna measurement systems  300  and airborne antenna measurement systems  300  may measure and record data about the antenna pattern produced by antenna  120 . The antenna pattern of each antenna measurement system  300  may be known, and the antenna pattern for each transmit beam and receive beam produced by each antenna measurement system  300  may be identical or substantively similar. The antenna pattern of each antenna measurement system  300  may have different gain levels at different geographic locations, altitudes or orientations. The antenna pattern data produced by antenna  120  may be measured and recorded by each antenna measurement system  300 . Location and orientation data (e.g., roll pitch, yaw, and altitude) may be accounted for to accurately characterize the antenna pattern produced by antenna  120  on aircraft  100 . Although this disclosure discusses measuring an unknown antenna pattern in a particular manner, this disclosure contemplates measuring an unknown antenna pattern in any suitable manner. 
     In particular embodiments, a second arrangement may provide for an aircraft  100  that is stationary and one or more antenna measurement systems  300  that are in motion. As an example and not by way of limitation, aircraft  100  may either be parked on the ground or suspended in the air by a crane. One or more antenna measurement systems  300  may be mounted to one or more N-copters or ground vehicles. The N-copters or ground vehicles may then travel around aircraft  100  while antenna  120  is producing an antenna pattern. The antenna measurement systems  300  may measure and record the antenna pattern produced by antenna  120 . The antenna pattern of each antenna measurement system may be known, and the antenna pattern for each transmit beam and receive beam may be identical. The antenna pattern of each antenna measurement system  300  may be known, and the antenna pattern for each transmit beam and receive beam produced by each antenna measurement system  300  may be identical or substantively similar. The antenna pattern of each antenna measurement system  300  may have different gain levels at different geographic locations, altitudes or orientations. The antenna pattern data produced by antenna  120  may be measured and recorded by each antenna measurement system  300 . Location and orientation data (e.g., roll pitch, yaw, and altitude) may be accounted for to accurately characterize the antenna pattern produced by antenna  120  on aircraft  100 . Although this disclosure discusses measuring an unknown antenna pattern in a particular manner, this disclosure contemplates measuring an unknown antenna pattern in any suitable manner. 
     In particular embodiments, a third arrangement may provide for an aircraft  100  and one or more antenna measurement systems  300  that are all in motion. As an example and not by way of limitation, aircraft  100  may be in flight, and one or more antenna measurement systems  300  may be mounted to one or more ground vehicles that are moving in relation to the DUT. (See slide 13—example 3). Alternatively, aircraft  100  may be in flight, and one or more antenna measurement systems may be mounted to one or more aerial vehicles, which are moving in relation to aircraft  100 . Alternatively, aircraft  100  may be in flight, and one or more antenna measurement systems may be mounted to one or more aerial vehicles  520  and ground vehicles, which may be moving in relation to aircraft  100 . The antenna measurement systems  300  may measure and record the antenna pattern produced by antenna  120 . The antenna pattern of each antenna measurement system may be known, and the antenna pattern for each transmit beam and receive beam may be identical. The antenna pattern of each antenna measurement system  300  may be known, and the antenna pattern for each transmit beam and receive beam produced by each antenna measurement system  300  may be identical or substantively similar. The antenna pattern of each antenna measurement system  300  may have different gain levels at different geographic locations, altitudes or orientations. The antenna pattern data produced by antenna  120  may be measured and recorded by each antenna measurement system  300 . Location and orientation data (e.g., roll pitch, yaw, and altitude) may be accounted for to accurately characterize the antenna pattern produced by antenna  120  on aircraft  100 . Although this disclosure discusses measuring an unknown antenna pattern in a particular manner, this disclosure contemplates measuring an unknown antenna pattern in any suitable manner. 
     In particular embodiments, a fourth arrangement may provide for an aircraft  100  that is in motion, and one or more antenna measurement systems mounted to vehicles  310 , some of which may be in motion and some of which may be stationary. As an example and not by way of limitation, antenna measurement systems  300  may be mounted to one or more base stations  510 , one or more ground vehicles, and to one or more airborne measurements systems  520 . Any combination of these antenna measurement systems  300  may be stationary in motion. As an example and not by way of limitation, antenna measurement systems  300  mounted to one or more base stations  510  may be stationary, some of airborne measurement systems  520  may be moving, and some of airborne measurement systems  530  may be stationary (e.g., hovering in the air). Aircraft  100  may be moving in relation to all or some antenna measurement systems  300 . The antenna measurement systems  300  may measure and record the antenna pattern produced by antenna  120 . The antenna pattern of each antenna measurement system may be known, and the antenna pattern for each transmit beam and receive beam may be identical. The antenna pattern of each antenna measurement system  300  may be known, and the antenna pattern for each transmit beam and receive beam produced by each antenna measurement system  300  may be identical or substantively similar. The antenna pattern of each antenna measurement system  300  may have different gain levels at different geographic locations, altitudes or orientations. The antenna pattern data produced by antenna  120  may be measured and recorded by each antenna measurement system  300 . Location and orientation data (e.g., roll pitch, yaw, and altitude) may be accounted for to accurately characterize the antenna pattern produced by antenna  120  on aircraft  100 . Although this disclosure discusses measuring an unknown antenna pattern in a particular manner, this disclosure contemplates measuring an unknown antenna pattern in any suitable manner. 
     This disclosure contemplates various applications of antenna measurement system  300 , and antenna measurement system arrangements  400  and  500 . As an example and not by way of limitation, this disclosure contemplates antenna measurement systems that measure and characterize antenna patterns produced by antennas mounted to land and marine vehicles, the antenna patterns of terrestrial antenna installations (e.g., installations in remote locations), measurement of high gain systems requiring a long antenna range (e.g., the DUT can point upwards to minimize antenna range footprint and interference with other systems during tests), measurement of antenna patterns of large apertures in the field (large apertures need to be measured with a near-field scanner, compact range, or outdoor far-field range), and 3D characterization of communication channels and channel sounding. 
       FIG. 6  illustrates an example method  600  for accurately characterizing an antenna pattern produced by antenna  120  mounted on an aircraft. The method may begin at step  610 , where an antenna measurement system may determine a transmitted or received power at a transmitting or receiving antenna mounted to an antenna measurement system from a transmitting or receiving antenna mounted to a device under test (DUT) in motion relative to the antenna measurement system. At step  620 , the antenna measurement system may determine one or more first orientation parameters of the antenna measurement system. At step  630 , the antenna measurement system may determine one or more second orientation parameters of the DUT. At step  640 , the antenna measurement system may determine an antenna pattern of the transmitting antenna based on the received power, the first orientation parameters, and the second orientation parameters. Particular embodiments may repeat one or more steps of the method of  FIG. 6 , where appropriate. Although this disclosure describes and illustrates particular steps of the method of  FIG. 6  as occurring in a particular order, this disclosure contemplates any suitable steps of the method of  FIG. 6  occurring in any suitable order. Moreover, although this disclosure describes and illustrates an example method for accurately characterizing an antenna pattern produced by an antenna mounted on an aircraft including the particular steps of the method of  FIG. 6 , this disclosure contemplates any suitable method for accurately characterizing an antenna pattern produced by an antenna mounted on an aircraft including any suitable steps, which may include all, some, or none of the steps of the method of  FIG. 6 , where appropriate. Furthermore, although this disclosure describes and illustrates particular components, devices, or systems carrying out particular steps of the method of  FIG. 6 , this disclosure contemplates any suitable combination of any suitable components, devices, or systems carrying out any suitable steps of the method of  FIG. 6 . 
       FIG. 7  illustrates an example computer system  700  that may be implemented on antenna measurement system  300 . In particular embodiments, one or more computer systems  700  perform one or more steps of one or more methods described or illustrated herein. In particular embodiments, one or more computer systems  700  provide functionality described or illustrated herein. In particular embodiments, software running on one or more computer systems  700  performs one or more steps of one or more methods described or illustrated herein or provides functionality described or illustrated herein. Particular embodiments include one or more portions of one or more computer systems  700 . Herein, reference to a computer system may encompass a computing device, and vice versa, where appropriate. Moreover, reference to a computer system may encompass one or more computer systems, where appropriate. 
     This disclosure contemplates any suitable number of computer systems  700 . This disclosure contemplates computer system  700  taking any suitable physical form. As example and not by way of limitation, computer system  700  may be an embedded computer system, a system-on-chip (SOC), a single-board computer system (SBC) (such as, for example, a computer-on-module (COM) or system-on-module (SOM)), a desktop computer system, a laptop or notebook computer system, an interactive kiosk, a mainframe, a mesh of computer systems, a mobile telephone, a personal digital assistant (PDA), a server, a tablet computer system, an augmented/virtual reality device, or a combination of two or more of these. Where appropriate, computer system  700  may include one or more computer systems  700 ; be unitary or distributed; span multiple locations; span multiple machines; span multiple data centers; or reside in a cloud, which may include one or more cloud components in one or more networks. Where appropriate, one or more computer systems  700  may perform without substantial spatial or temporal limitation one or more steps of one or more methods described or illustrated herein. As an example and not by way of limitation, one or more computer systems  700  may perform in real time or in batch mode one or more steps of one or more methods described or illustrated herein. One or more computer systems  700  may perform at different times or at different locations one or more steps of one or more methods described or illustrated herein, where appropriate. 
     In particular embodiments, computer system  700  includes a processor  702 , memory  704 , storage  706 , an input/output (I/O) interface  708 , a communication interface  710 , and a bus  712 . Although this disclosure describes and illustrates a particular computer system having a particular number of particular components in a particular arrangement, this disclosure contemplates any suitable computer system having any suitable number of any suitable components in any suitable arrangement. 
     In particular embodiments, processor  702  includes hardware for executing instructions, such as those making up a computer program. As an example and not by way of limitation, to execute instructions, processor  702  may retrieve (or fetch) the instructions from an internal register, an internal cache, memory  704 , or storage  706 ; decode and execute them; and then write one or more results to an internal register, an internal cache, memory  704 , or storage  706 . In particular embodiments, processor  702  may include one or more internal caches for data, instructions, or addresses. This disclosure contemplates processor  702  including any suitable number of any suitable internal caches, where appropriate. As an example and not by way of limitation, processor  702  may include one or more instruction caches, one or more data caches, and one or more translation lookaside buffers (TLBs). Instructions in the instruction caches may be copies of instructions in memory  704  or storage  706 , and the instruction caches may speed up retrieval of those instructions by processor  702 . Data in the data caches may be copies of data in memory  704  or storage  706  for instructions executing at processor  702  to operate on; the results of previous instructions executed at processor  702  for access by subsequent instructions executing at processor  702  or for writing to memory  704  or storage  706 ; or other suitable data. The data caches may speed up read or write operations by processor  702 . The TLBs may speed up virtual-address translation for processor  702 . In particular embodiments, processor  702  may include one or more internal registers for data, instructions, or addresses. This disclosure contemplates processor  702  including any suitable number of any suitable internal registers, where appropriate. Where appropriate, processor  702  may include one or more arithmetic logic units (ALUs); be a multi-core processor; or include one or more processors  702 . Although this disclosure describes and illustrates a particular processor, this disclosure contemplates any suitable processor. 
     In particular embodiments, memory  704  includes main memory for storing instructions for processor  702  to execute or data for processor  702  to operate on. As an example and not by way of limitation, computer system  700  may load instructions from storage  706  or another source (such as, for example, another computer system  700 ) to memory  704 . Processor  702  may then load the instructions from memory  704  to an internal register or internal cache. To execute the instructions, processor  702  may retrieve the instructions from the internal register or internal cache and decode them. During or after execution of the instructions, processor  702  may write one or more results (which may be intermediate or final results) to the internal register or internal cache. Processor  702  may then write one or more of those results to memory  704 . In particular embodiments, processor  702  executes only instructions in one or more internal registers or internal caches or in memory  704  (as opposed to storage  706  or elsewhere) and operates only on data in one or more internal registers or internal caches or in memory  704  (as opposed to storage  706  or elsewhere). One or more memory buses (which may each include an address bus and a data bus) may couple processor  702  to memory  704 . Bus  712  may include one or more memory buses, as described below. In particular embodiments, one or more memory management units (MMUs) reside between processor  702  and memory  704  and facilitate accesses to memory  704  requested by processor  702 . In particular embodiments, memory  704  includes random access memory (RAM). This RAM may be volatile memory, where appropriate Where appropriate, this RAM may be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, where appropriate, this RAM may be single-ported or multi-ported RAM. This disclosure contemplates any suitable RAM. Memory  704  may include one or more memories  704 , where appropriate. Although this disclosure describes and illustrates particular memory, this disclosure contemplates any suitable memory. 
     In particular embodiments, storage  706  includes mass storage for data or instructions. As an example and not by way of limitation, storage  706  may include a hard disk drive (HDD), a floppy disk drive, flash memory, an optical disc, a magneto-optical disc, magnetic tape, or a Universal Serial Bus (USB) drive or a combination of two or more of these. Storage  706  may include removable or non-removable (or fixed) media, where appropriate. Storage  706  may be internal or external to computer system  700 , where appropriate. In particular embodiments, storage  706  is non-volatile, solid-state memory. In particular embodiments, storage  706  includes read-only memory (ROM). Where appropriate, this ROM may be mask-programmed ROM, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM), or flash memory or a combination of two or more of these. This disclosure contemplates mass storage  706  taking any suitable physical form. Storage  706  may include one or more storage control units facilitating communication between processor  702  and storage  706 , where appropriate. Where appropriate, storage  706  may include one or more storages  706 . Although this disclosure describes and illustrates particular storage, this disclosure contemplates any suitable storage. 
     In particular embodiments, I/O interface  708  includes hardware, software, or both, providing one or more interfaces for communication between computer system  700  and one or more I/O devices. Computer system  700  may include one or more of these I/O devices, where appropriate. One or more of these I/O devices may enable communication between a person and computer system  700 . As an example and not by way of limitation, an I/O device may include a keyboard, keypad, microphone, monitor, mouse, printer, scanner, speaker, still camera, stylus, tablet, touch screen, trackball, video camera, another suitable I/O device or a combination of two or more of these. An I/O device may include one or more sensors. This disclosure contemplates any suitable I/O devices and any suitable I/O interfaces  708  for them. Where appropriate, I/O interface  708  may include one or more device or software drivers enabling processor  702  to drive one or more of these I/O devices. I/O interface  708  may include one or more I/O interfaces  708 , where appropriate. Although this disclosure describes and illustrates a particular I/O interface, this disclosure contemplates any suitable I/O interface. 
     In particular embodiments, communication interface  710  includes hardware, software, or both providing one or more interfaces for communication (such as, for example, packet-based communication) between computer system  700  and one or more other computer systems  700  or one or more networks. As an example and not by way of limitation, communication interface  710  may include a network interface controller (NIC) or network adapter for communicating with an Ethernet or other wire-based network or a wireless NIC (WNIC) or wireless adapter for communicating with a wireless network, such as a WI-FI network. This disclosure contemplates any suitable network and any suitable communication interface  710  for it. As an example and not by way of limitation, computer system  700  may communicate with an ad hoc network, a personal area network (PAN), a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), or one or more portions of the Internet or a combination of two or more of these. One or more portions of one or more of these networks may be wired or wireless. As an example, computer system  700  may communicate with a wireless PAN (WPAN) (such as, for example, a BLUETOOTH WPAN), a WI-FI network, a WI-MAX network, a cellular telephone network (such as, for example, a Global System for Mobile Communications (GSM) network), or other suitable wireless network or a combination of two or more of these. Computer system  700  may include any suitable communication interface  710  for any of these networks, where appropriate. Communication interface  710  may include one or more communication interfaces  710 , where appropriate. Although this disclosure describes and illustrates a particular communication interface, this disclosure contemplates any suitable communication interface. 
     In particular embodiments, bus  712  includes hardware, software, or both coupling components of computer system  700  to each other. As an example and not by way of limitation, bus  712  may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a front-side bus (FSB), a HYPERTRANSPORT (HT) interconnect, an Industry Standard Architecture (ISA) bus, an INFINIBAND interconnect, a low-pin-count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCIe) bus, a serial advanced technology attachment (SATA) bus, a Video Electronics Standards Association local (VLB) bus, or another suitable bus or a combination of two or more of these. Bus  712  may include one or more buses  712 , where appropriate. Although this disclosure describes and illustrates a particular bus, this disclosure contemplates any suitable bus or interconnect. 
     Herein, a computer-readable non-transitory storage medium or media may include one or more semiconductor-based or other integrated circuits (ICs) (such, as for example, field-programmable gate arrays (FPGAs) or application-specific ICs (ASICs)), hard disk drives (HDDs), hybrid hard drives (HHDs), optical discs, optical disc drives (ODDs), magneto-optical discs, magneto-optical drives, floppy diskettes, floppy disk drives (FDDs), magnetic tapes, solid-state drives (SSDs), RAM-drives, SECURE DIGITAL cards or drives, any other suitable computer-readable non-transitory storage media, or any suitable combination of two or more of these, where appropriate. A computer-readable non-transitory storage medium may be volatile, non-volatile, or a combination of volatile and non-volatile, where appropriate. 
     Herein, “or” is inclusive and not exclusive, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A or B” means “A, B, or both,” unless expressly indicated otherwise or indicated otherwise by context. Moreover, “and” is both joint and several, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A and B” means “A and B, jointly or severally,” unless expressly indicated otherwise or indicated otherwise by context. 
     The scope of this disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments described or illustrated herein that a person having ordinary skill in the art would comprehend. The scope of this disclosure is not limited to the example embodiments described or illustrated herein. Moreover, although this disclosure describes and illustrates respective embodiments herein as including particular components, elements, feature, functions, operations, or steps, any of these embodiments may include any combination or permutation of any of the components, elements, features, functions, operations, or steps described or illustrated anywhere herein that a person having ordinary skill in the art would comprehend. Furthermore, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Additionally, although this disclosure describes or illustrates particular embodiments as providing particular advantages, particular embodiments may provide none, some, or all of these advantages.