PATENT DOCUMENT

Publication Number: US-10826177-B2
Application Number: US-201815907029-A
Country: US
Kind Code: B2

Title: Electronic devices having phased antenna arrays for performing proximity detection operations

Abstract:
An electronic device may be provided with wireless circuitry that includes a phased antenna array. The array may include multiple antennas each having multiple antenna feeds for covering different polarizations. Control circuitry may control the wireless circuitry to transmit signals at millimeter or centimeter wave frequencies using a first set of feeds in the array and at least one selected phase. The wireless circuitry may receive the signals transmitted by the first set of feeds using a second set of feeds in the array. The control circuitry may gather phase measurements for the received signals and may compare the phase measurements to the selected phase to generate phase difference values. The control circuitry may perform external object proximity detection operations based on the phase difference values. The control circuitry may control the wireless circuitry to cycle through different combinations of antenna feeds for the first and second sets.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 transceiver circuitry in the housing and configured to generate radio-frequency signals at a frequency greater than 10 GHz; 
 a phased antenna array in the housing and comprising first, second, and third antenna feeds coupled to the transceiver circuitry, wherein the first antenna feed is configured to transmit the radio-frequency signals at a predetermined phase and the second and third antenna feeds are configured to receive the radio-frequency signals transmitted by the first antenna feed; and 
 control circuitry in the housing, wherein the control circuitry is configured to:
 gather a first phase measurement value from the radio-frequency signals received by the second antenna feed and a second phase measurement value from the radio-frequency signals received by the third antenna feed, and 
 detect proximity of an object external to the housing based on a first difference between the predetermined phase and the first phase measurement value and a second difference between the predetermined phase and the second phase measurement value. 
 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the phased antenna array comprises first and second antennas, the first antenna feed is coupled to the first antenna, and the second antenna feed is coupled to the second antenna. 
     
     
       3. The electronic device defined in  claim 2 , wherein the phased antenna array comprises a third antenna, the third antenna feed being coupled to the third antenna. 
     
     
       4. The electronic device defined in  claim 2 , wherein the second and third antenna feeds cover orthogonal polarizations and the third antenna feed is coupled to the second antenna. 
     
     
       5. The electronic device defined in  claim 4 , wherein the orthogonal polarizations comprise vertical and horizontal linear polarizations, the transceiver circuitry comprising a vertical polarization transceiver coupled to the second antenna feed and a horizontal polarization transceiver coupled to the third antenna feed. 
     
     
       6. The electronic device defined in  claim 1 , further comprising:
 switching circuitry coupled between the phased antenna array and the transceiver circuitry, wherein the control circuitry is configured to: 
 control the switching circuitry to configure the second antenna feed to transmit the radio-frequency signals and to configure the first antenna feed to receive the radio-frequency signals transmitted by the second antenna feed, 
 gather an additional phase measurement value from the radio-frequency signals received by the first antenna feed, and 
 detect the proximity of the object based on the gathered additional phase measurement value. 
 
     
     
       7. The electronic device defined in  claim 1 , further comprising:
 beam steering circuitry coupled to first antenna feed, wherein the control circuitry is configured to: 
 control the beam steering circuitry to transmit the radio-frequency signals at a predetermined phase using the first antenna feed, and 
 identify a phase difference value between the predetermined phase and the gathered phase measurement value. 
 
     
     
       8. The electronic device defined in  claim 7 , wherein the control circuitry is configured to:
 generate a comparison value by computing a difference between the identified phase difference value and a predetermined phase difference value; and 
 compare the generated comparison value to a predetermined maximum threshold value. 
 
     
     
       9. The electronic device defined in  claim 8 , wherein the control circuitry is configured to disable the phased antenna array in response to determining that the generated comparison value exceeds the predetermined maximum threshold value. 
     
     
       10. The electronic device defined in  claim 9 , wherein the first antenna feed is configured to transmit the radio-frequency signals at a first power level and the control circuitry is further configured to:
 control the first antenna feed to transmit the radio-frequency signals at a second power level that is greater than the first power level in response to determining that the generated comparison value does not exceed the predetermined maximum threshold value. 
 
     
     
       11. The electronic device defined in  claim 1 , further comprising:
 sensor circuitry configured to generate sensor data, wherein the control circuitry is configured to perform the external object detection operations based on the sensor data. 
 
     
     
       12. An electronic device, comprising:
 wireless communications circuitry configured to perform cellular telephone communications, the wireless communications circuitry including transceiver circuitry and a phased antenna array coupled to the transceiver circuitry, wherein the transceiver circuitry is configured to transmit radio-frequency signals at a frequency between 10 GHz and 300 GHz; and 
 control circuitry coupled to the wireless communications circuitry, wherein the control circuitry is configured to:
 control the wireless communications circuitry to transmit the radio-frequency signals over a first set of antenna feeds in the phased antenna array using a selected phase, 
 control the wireless communications circuitry to receive the radio-frequency signals transmitted by the first set of antenna feeds using a second set of antenna feeds in the phased antenna array that is different from the first set of antenna feeds, 
 identify a phase difference value between the radio-frequency signals received using the second set of antenna feeds and the selected phase used to transmit the radio-frequency signals over the first set of antenna feeds, and 
 determine whether a difference between the generated phase difference value and a calibrated phase difference value exceeds a threshold value, wherein the calibrated phase difference value is associated with an absence of an external object. 
 
 
     
     
       13. The electronic device defined in  claim 12 , wherein the control circuitry is configured to disable the phased antenna array in response to determining that the difference between the generated phase difference value and the calibrated phase difference value exceeds the threshold value. 
     
     
       14. The electronic device defined in  claim 13 , wherein the wireless communications circuitry further comprises:
 an additional phased antenna array coupled to the transceiver circuitry, wherein the control circuitry is configured to control the wireless communications circuitry to transmit the radio-frequency signals over the additional phased antenna array in response to determining that the difference between the generated phase difference value and the calibrated phase difference value exceeds the threshold value. 
 
     
     
       15. The electronic device defined in  claim 13 , wherein the wireless communications circuitry is configured to transmit the radio-frequency signals at a transmit power level and the control circuitry is further configured to control the wireless communications circuitry to increase the transmit power level in response to determining that the difference between the generated phase difference value and the calibrated phase difference value is less than the threshold value. 
     
     
       16. The electronic device defined in  claim 12 , wherein the control circuitry is further configured to:
 control the wireless communications circuitry to transmit the radio-frequency signals over a third set of antenna feeds in the phased antenna array using an additional selected phase, 
 control the wireless communications circuitry to receive the radio-frequency signals transmitted by the third set of antenna feeds using a fourth set of antenna feeds in the phased antenna array, 
 identify an additional phase difference value between the radio-frequency signals received using the fourth set of antenna feeds and the selected additional phase used to transmit the radio-frequency signals over the third set of antenna feeds, and 
 compare the additional phase difference value to an additional calibrated phase difference value. 
 
     
     
       17. The electronic device defined in  claim 12 , wherein the first set of antenna feeds comprises a vertically polarized antenna feed and the second set of antenna feeds comprises a horizontally polarized antenna feed. 
     
     
       18. An electronic device comprising:
 a housing having peripheral conductive housing structures; 
 a touch screen display mounted to the peripheral conductive housing structures; 
 a phased antenna array that is mounted in the housing and that is configured to convey millimeter wave signals; 
 beam steering circuitry in the housing and coupled to the phased antenna array, wherein the beam steering circuitry is configured to control the phased antenna array to transmit the millimeter wave signals with a selected phase; 
 transceiver circuitry in the housing and configured to use the phased antenna array to receive the millimeter wave signals transmitted by the phased antenna array; 
 phase measurement circuitry configured to perform a phase measurement on the millimeter wave signals received using the phased antenna array; and 
 control circuitry in the housing, wherein the control circuitry is configured to:
 identify a phase difference between the phase measurement performed by the phase measurement circuitry and the selected phase, and 
 perform external object proximity detection operations based on the identified phase difference. 
 
 
     
     
       19. The electronic device defined in  claim 1 , wherein the transceiver circuitry includes cellular telephone transceiver circuitry.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices often include wireless communications circuitry. For example, cellular telephones, computers, and other devices often contain antennas and wireless transceivers for supporting wireless communications. 
     It may be desirable to support wireless communications in millimeter wave and centimeter wave communications bands. Millimeter wave communications, which are sometimes referred to as extremely high frequency (EHF) communications, and centimeter wave communications involve communications at frequencies of about 10-300 GHz. Operation at these frequencies may support high bandwidths, but may raise significant challenges. For example, millimeter wave communications signals generated by antennas can be characterized by substantial attenuation and/or distortion during signal propagation through various mediums. In addition, if care is not taken, external objects in the vicinity of the electronic device may block millimeter wave communications signals in certain directions. Industry or government standards or regulations may also impose limits on the amount of millimeter wave energy that is absorbed by external objects such as the user&#39;s body in the vicinity of the electronic device. 
     It would therefore be desirable to be able to provide electronic devices with improved wireless communications capabilities for supporting communications at frequencies greater than 10 GHz. 
     SUMMARY 
     An electronic device may be provided with wireless communications circuitry. The wireless communications circuitry may include antennas arranged in a phased antenna array and transceiver circuitry such as centimeter and millimeter wave transceiver circuitry (e.g., circuitry that transmits and receives radio-frequency signals at frequencies greater than 10 GHz). 
     The phased antenna array may include multiple antennas each having multiple antenna feeds such as horizontally-polarized antenna feeds and vertically-polarized antenna feeds. Beam steering circuitry such as one or more phase and magnitude controllers may be coupled to the antenna feeds in the phased antenna array. Switching circuitry may be coupled between the transceiver circuitry and the beam steering circuitry. Control circuitry in the electronic device may control the wireless communications circuitry to transmit the radio-frequency signals using a first set of antenna feeds in the phased antenna array with at least one selected phase. The control circuitry may control the wireless communications circuitry to receive the radio-frequency signals transmitted by the first set of antenna feeds using a second set of antenna feeds in the phased antenna array (e.g., the second set of antenna feeds may receive the transmitted radio-frequency signals over-the-air). 
     Phase measurement circuitry may gather phase measurement values for the radio-frequency signals received by the second set of antenna feeds. The control circuitry may compare the gathered phase measurement values to the at least one selected phase to generate phase difference values between the first and second sets of antenna feeds. The control circuitry may perform external object proximity detection operations based on the phase difference values (e.g., to detect the proximity of an object external to the device such as a user&#39;s body, clothing, or other objects). For example, the control circuitry may determine whether differences between the generated phase difference values and calibrated phase difference values stored at the electronic device (e.g., predetermined free space phase difference values) exceed a threshold value. 
     If the differences between the generated phase difference values and the calibrated phase difference values exceed the threshold value, this may be indicative of an external object in close proximity to the phased antenna array (e.g., within a predetermined distance of the phased antenna array). The control circuitry may subsequently disable the phased antenna array and may switch a different phased antenna array into use. If the differences between the generated phase difference values and the calibrated phase difference values do not exceed the threshold value, this may be indicative of the absence of an external object in close proximity to the phased antenna array. The control circuitry may subsequently increase the transmit power level of the wireless communications circuitry to maximize wireless performance at millimeter and centimeter wave frequencies. The control circuitry may control the wireless communications circuitry to cycle through different combinations of antenna feeds in the first and second sets to characterize phase differences across the entire phased antenna array if desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 3  is a diagram of an illustrative phased antenna array that may be adjusted using control circuitry to direct a beam of signals in accordance with an embodiment. 
         FIG. 4  is a diagram of an illustrative transceiver and antenna in accordance with an embodiment. 
         FIG. 5  is a perspective view of an illustrative antenna having multiple feeds for handling radio-frequency signals with different polarizations in accordance with an embodiment. 
         FIG. 6  is a circuit diagram of illustrative wireless communications circuitry having a phased antenna array with proximity detection capabilities in accordance with an embodiment. 
         FIG. 7  is a side view of an illustrative phased antenna array showing how electromagnetic coupling between antennas in the phased antenna array may be influenced by the presence of an external object in accordance with an embodiment. 
         FIG. 8  is a flow chart of illustrative steps that may be performed by an electronic device of the type shown in  FIGS. 1-7  for detecting the proximity of external objects using a phased antenna array in accordance with an embodiment. 
         FIG. 9  is an illustrative table of exemplary phase difference values that may be generated by a phased antenna array in detecting the proximity of external object in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may contain wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include phased antenna arrays that are used for handling millimeter wave and centimeter wave communications. Millimeter wave communications, which are sometimes referred to as extremely high frequency (EHF) communications, involve signals at 60 GHz or other frequencies between about 30 GHz and 300 GHz. Centimeter wave communications involve signals at frequencies between about 10 GHz and 30 GHz. If desired, device  10  may also contain wireless communications circuitry for handling satellite navigation system signals, cellular telephone signals, local wireless area network signals, near-field communications, light-based wireless communications, or other wireless communications. 
     Electronic devices such as device  10  in  FIG. 1  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device, a pendant device, a headphone or earpiece device, a virtual or augmented reality headset device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, a wireless access point or base station (e.g., a wireless router or other equipment for routing communications between other wireless devices and a larger network such as the internet or a cellular telephone network), a desktop computer, a keyboard, a gaming controller, a computer mouse, a mousepad, a trackpad or touchpad, equipment that implements the functionality of two or more of these devices, or other electronic equipment. The above-mentioned examples are merely illustrative. Other configurations may be used for electronic device if desired. 
     As shown in  FIG. 1 , device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material (e.g., glass, ceramic, plastic, sapphire, etc.). In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may have a display such as display  14 . Display  14  may be mounted on the front face of device  10 . Display  14  may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. The rear face of housing  12  (i.e., the face of device  10  opposing the front face of device  10 ) may have a planar rear housing wall. If desired, the rear housing wall may have slots that pass entirely through the rear housing wall and that therefore separate housing wall portions of housing  12  from each other. The rear housing wall may include conductive portions and/or dielectric portions. If desired, the rear housing wall may include a planar metal layer covered by a thin layer or coating of dielectric such as glass, plastic, sapphire, or ceramic. Housing  12  (e.g., the rear housing wall, sidewalls, etc.) may also have shallow grooves that do not pass entirely through housing  12 . The slots and grooves may be filled with plastic or other dielectric. If desired, portions of housing  12  that have been separated from each other (e.g., by a through slot) may be joined by internal conductive structures (e.g., sheet metal or other metal members that bridge the slot). 
     Display  14  may include pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable pixel structures. A display cover layer such as a layer of clear glass or plastic may cover the surface of display  14  or the outermost layer of display  14  may be formed from a color filter layer, thin-film transistor layer, or other display layer. Display  14  may contain an active area with an array of pixels (e.g., a central substantially rectangular portion). Inactive areas of the display that are free of pixels may form borders for the active area. If desired, the active area of display  14  may extend across some or all (e.g., substantially all) of the lateral front face of device  10  (e.g., from the left edge to the right edge and from the bottom edge to the top edge of the front face of device  10 ). 
     Housing  12  may include peripheral housing structures  12 W. Peripheral housing structures  12 W may run around the periphery of device  10  and display  14 . In configurations in which device  10  and display  14  have a rectangular shape with four edges, peripheral housing structures  12 W may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges (as an example). Peripheral housing structures  12 W or part of peripheral housing structures  12 W may serve as a bezel for display  14  (e.g., a cosmetic trim that surrounds all four sides of display  14  and/or that helps hold display  14  to device  10 ). Peripheral housing structures  12 W may, if desired, form sidewall structures for device  10  (e.g., by forming a metal band with vertical sidewalls, curved sidewalls, etc.). 
     Peripheral housing structures  12 W may be formed of a conductive material such as metal and may therefore sometimes be referred to as peripheral conductive housing structures, conductive housing structures, peripheral metal structures, or a peripheral conductive housing member (as examples). Peripheral conductive housing structures  12 W may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming peripheral conductive housing structures  12 W. 
     It is not necessary for peripheral conductive housing structures  12 W to have a uniform cross-section. For example, the top portion of peripheral conductive housing structures  12 W may, if desired, have an inwardly protruding lip that helps hold display  14  in place. The bottom portion of peripheral conductive housing structures  12 W may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). Peripheral conductive housing structures  12 W may have substantially straight vertical sidewalls, may have sidewalls that are curved, or may have other suitable shapes. In some configurations (e.g., when peripheral conductive housing structures  12 W serve as a bezel for display  14 ), the peripheral conductive housing structures may run around the lip of housing  12  (i.e., the peripheral conductive housing structures may cover only the edge of housing  12  that surrounds display  14  and not the rest of the sidewalls of housing  12 ). 
     If desired, housing  12  may have a conductive rear surface or wall such as wall  12 R (sometimes referred to herein as conductive rear housing wall  12 R). For example, housing  12  may be formed from a metal such as stainless steel or aluminum. The rear surface of housing  12  may lie in a plane that is parallel to display  14 . In configurations for device  10  in which the rear surface of housing  12  is formed from metal, it may be desirable to form parts of peripheral conductive housing structures  12 W as integral portions of the housing structures forming the rear surface of housing  12 . For example, conductive rear housing wall  12 R may be formed from a planar metal structure and portions of peripheral conductive housing structures  12 W on the sides of housing  12  may be formed as flat or curved vertically extending integral metal portions of the planar metal structure. Housing structures such as these may, if desired, be machined from a block of metal and/or may include multiple metal pieces that are assembled together to form housing  12 . Conductive rear housing wall  12 R may have one or more, two or more, or three or more portions. Peripheral conductive housing structures  12 W and/or conductive rear housing wall  12 R may form one or more exterior surfaces of device  10  (e.g., surfaces that are visible to a user of device  10 ) and/or may be implemented using internal structures that do not form exterior surfaces of device  10  (e.g., conductive housing structures that are not visible to a user of device  10  such as conductive structures that are covered with layers such as thin cosmetic layers, protective coatings, and/or other coating layers that may include dielectric materials such as glass, ceramic, plastic, or other structures that form the exterior surfaces of device  10  and/or serve to hide peripheral conductive housing structures  12 W and/or conductive rear housing wall  12 R from view of the user). 
     One or more antennas may be mounted within device  10  at one or more locations such as locations  8  shown in  FIG. 1 . Locations  8  may include, for example, locations at the corners of housing  12 , locations at or near the center of display  14 , locations along the peripheral edges of housing  12 , locations along peripheral conductive housing structures  12 W, locations on conductive rear housing wall  12 R, locations between the peripheral edges of housing  12  and the center of display  14 , locations under the display cover glass or other dielectric display cover layer that is used in covering and protecting display  14  on the front of device  10 , locations under a dielectric window on a rear face of housing  12  or the edge of housing  12 , or elsewhere in device  10 . In general, it may be desirable for antennas within housing  12  to be able to cover a full sphere around device  10  (e.g., so that device  10  can maintain satisfactory wireless communications with external equipment regardless of the orientation of device  10  with respect to the external equipment). Different arrays of multiple antennas may be mounted at respective locations on device  10  such as respective locations  8  or different antennas in a single array may be mounted at separate locations  8  if desired. If care is not taken, external objects such as the body of a user of device  10  or other objects external to device  10  may block antennas within housing  12  from covering a full sphere around device  10 . 
     A schematic diagram showing illustrative components that may be used in an electronic device such as electronic device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include storage and processing circuitry such as control circuitry  16 . Control circuitry  16  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  16  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processor integrated circuits, application specific integrated circuits, etc. 
     Control circuitry  16  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, control circuitry  16  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  16  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other wireless personal area network protocols, IEEE 802.11ad protocols, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols, etc. 
     Device  10  may include input-output circuitry  18 . Input-output circuitry  18  may include input-output devices  20 . Input-output devices  20  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  20  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, accelerometers or other components that can detect motion and device orientation relative to the Earth, capacitance sensors, proximity sensors (e.g., a capacitive proximity sensor and/or an infrared proximity sensor), magnetic sensors, and other sensors and input-output components. 
     Input-output circuitry  18  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas  40 , transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  30  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  22 ,  24 ,  26 , and  28 . 
     Transceiver circuitry  24  may be wireless local area network transceiver circuitry. Transceiver circuitry  24  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications or other wireless local area network (WLAN) bands and may handle the 2.4 GHz Bluetooth® communications band or other wireless personal area network (WPAN) bands. 
     Circuitry  34  may use cellular telephone transceiver circuitry  26  for handling wireless communications in frequency ranges such as a low communications band from 600 to 960 MHz, a midband from 1710 to 2170 MHz, a high band from 2300 to 2700 MHz, an ultra-high band from 3400 to 3700 MHz, or other communications bands between 600 MHz and 4000 MHz or other suitable frequencies (as examples). Circuitry  26  may handle voice data and non-voice data. 
     Millimeter wave transceiver circuitry  28  (sometimes referred to as extremely high frequency (EHF) transceiver circuitry  28  or transceiver circuitry  28 ) may support communications at frequencies between about 10 GHz and 300 GHz. For example, transceiver circuitry  28  may support communications in Extremely High Frequency (EHF) or millimeter wave communications bands between about 30 GHz and 300 GHz and/or in centimeter wave communications bands between about 10 GHz and 30 GHz (sometimes referred to as Super High Frequency (SHF) bands). As examples, transceiver circuitry  28  may support communications in an IEEE K communications band between about 18 GHz and 27 GHz, a K a  communications band between about 26.5 GHz and 40 GHz, a Ku communications band between about 12 GHz and 18 GHz, a V communications band between about 40 GHz and 75 GHz, a W communications band between about 75 GHz and 110 GHz, or any other desired frequency band between approximately 10 GHz and 300 GHz. If desired, circuitry  28  may support IEEE 802.11ad communications at 60 GHz and/or 5th generation mobile networks or 5th generation wireless systems (5G) communications bands between 27 GHz and 90 GHz. If desired, circuitry  28  may support communications at multiple frequency bands between 10 GHz and 300 GHz such as a first band from 27.5 GHz to 28.5 GHz, a second band from 37 GHz to 41 GHz, and a third band from 57 GHz to 71 GHz, or other communications bands between 10 GHz and 300 GHz. Circuitry  28  may be formed from one or more integrated circuits (e.g., multiple integrated circuits mounted on a common printed circuit in a system-in-package device, one or more integrated circuits mounted on different substrates, etc.). While circuitry  28  is sometimes referred to herein as millimeter wave transceiver circuitry  28 , millimeter wave transceiver circuitry  28  may handle communications at any desired communications bands at frequencies between 10 GHz and 300 GHz (e.g., transceiver circuitry  28  may transmit and receive radio-frequency signals in millimeter wave communications bands, centimeter wave communications bands, etc.). 
     Wireless communications circuitry  34  may include satellite navigation system circuitry such as Global Positioning System (GPS) receiver circuitry  22  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., GLONASS signals at 1609 MHz). Satellite navigation system signals for receiver  22  are received from a constellation of satellites orbiting the earth. 
     In satellite navigation system links, cellular telephone links, and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. In WiFi® and Bluetooth® links at 2.4 and 5 GHz and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. Millimeter wave transceiver circuitry  28  may convey signals that travel (over short distances) between a transmitter and a receiver over a line-of-sight path. To enhance signal reception for millimeter and centimeter wave communications, phased antenna arrays and beam steering techniques may be used (e.g., schemes in which antenna signal phase and/or magnitude for each antenna in an array is adjusted to perform beam steering). Antenna diversity schemes may also be used to ensure that the antennas that have become blocked or that are otherwise degraded due to the operating environment of device  10  can be switched out of use and higher-performing antennas used in their place. 
     Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. 
     Antennas  40  in wireless communications circuitry  34  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, stacked patch antenna structures, antenna structures having parasitic elements, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, monopoles, dipoles, helical antenna structures, Yagi (Vagi-Uda) antenna structures, surface integrated waveguide structures, hybrids of these designs, etc. If desired, one or more of antennas  40  may be cavity-backed antennas. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. Dedicated antennas may be used for receiving satellite navigation system signals or, if desired, antennas  40  can be configured to receive both satellite navigation system signals and signals for other communications bands (e.g., wireless local area network signals and/or cellular telephone signals). Antennas  40  can be arranged in phased antenna arrays for handling millimeter wave communications. 
     Transmission line paths may be used to route antenna signals within device  10  (e.g., signals that are transmitted or received over-the-air by antennas  40 ). For example, transmission line paths may be used to couple antennas  40  to transceiver circuitry  30 . Transmission line paths in device  10  may include coaxial cable paths, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, waveguide structures for conveying signals at millimeter wave frequencies (e.g., coplanar waveguides or grounded coplanar waveguides), transmission lines formed from combinations of transmission lines of these types, etc. 
     Transmission line paths in device  10  may be integrated into rigid and/or flexible printed circuit boards if desired. In one suitable arrangement, transmission line paths in device  10  may include transmission line conductors (e.g., signal and/or ground conductors) that are integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive) that may be folded or bent in multiple dimensions (e.g., two or three dimensions) and that maintain a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). All of the multiple layers of the laminated structures may be batch laminated together (e.g., in a single pressing process) without adhesive (e.g., as opposed to performing multiple pressing processes to laminate multiple layers together with adhesive). Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within the transmission lines, if desired. 
     Device  10  may contain multiple antennas  40 . The antennas may be used together or one of the antennas may be switched into use while other antenna(s) are switched out of use. If desired, control circuitry  16  may be used to select an optimum antenna to use in device  10  in real time and/or to select an optimum setting for adjustable wireless circuitry associated with one or more of antennas  40 . Antenna adjustments may be made to tune antennas to perform in desired frequency ranges, to perform beam steering with a phased antenna array, and to otherwise optimize antenna performance. Sensors may be incorporated into antennas  40  to gather sensor data in real time that is used in adjusting antennas  40  if desired. 
     In some configurations, antennas  40  may include antenna arrays such as phased antenna arrays that implement beam steering functions. For example, the antennas that are used in handling millimeter wave and centimeter wave signals for transceiver circuitry  28  may be implemented in one or more phased antenna arrays. The radiating elements in a phased antenna array for supporting millimeter wave and centimeter wave communications may be patch antennas, dipole antennas, Yagi (Yagi-Uda) antennas, or other suitable antennas. Transceiver circuitry  28  can be integrated with the phased antenna arrays to form integrated phased antenna array and transceiver circuit modules or packages if desired. 
     In devices such as handheld devices, the presence of an external object such as the hand of a user or a table or other surface on which a device is resting has a potential to block wireless signals such as millimeter wave signals. In addition, millimeter wave communications typically require a line of sight between antennas  40  and the antennas on an external device. Accordingly, it may be desirable to incorporate multiple phased antenna arrays into device  10 , each of which is placed in a different location within or on device  10  (e.g., at different locations such as locations  8  of  FIG. 1  or other locations). With this type of arrangement, an unblocked phased antenna array may be switched into use and, once switched into use, the phased antenna array may use beam steering to optimize wireless performance. Similarly, if a phased antenna array does not face or have a line of sight to an external device, another phased antenna array that has line of sight to the external device may be switched into use and that phased antenna array may use beam steering to optimize wireless performance. Configurations in which antennas from one or more different locations in device  10  are operated together may also be used (e.g., to form a phased antenna array, etc.). 
       FIG. 3  shows how antennas  40  on device  10  may be formed in a phased antenna array. As shown in  FIG. 3 , phased antenna array  60  (sometimes referred to herein as array  60 , antenna array  60 , or array  60  of antennas  40 ) may be coupled to signal paths such as transmission line paths  64  (e.g., one or more radio-frequency transmission lines). For example, a first antenna  40 - 1  in phased antenna array  60  may be coupled to a first transmission line path  64 - 1 , a second antenna  40 - 2  in phased antenna array  60  may be coupled to a second transmission line path  64 - 2 , an Nth antenna  40 -N in phased antenna array  60  may be coupled to an Nth transmission line path  64 -N, etc. 
     Antennas  40  in phased antenna array  60  may be arranged in any desired number of rows and columns or in any other desired pattern (e.g., the antennas need not be arranged in a grid pattern having rows and columns). During signal transmission operations, transmission line paths  64  may be used to supply signals (e.g., radio-frequency signals such as millimeter wave and/or centimeter wave signals) from transceiver circuitry  28  ( FIG. 2 ) to phased antenna array  60  for wireless transmission to external wireless equipment. During signal reception operations, transmission line paths  64  may be used to convey signals received at phased antenna array  60  from external equipment to transceiver circuitry  28  ( FIG. 2 ). 
     The use of multiple antennas  40  in phased antenna array  60  allows beam steering arrangements to be implemented by controlling the relative phases and magnitudes (amplitudes) of the radio-frequency signals conveyed by the antennas. In the example of  FIG. 3 , antennas  40  each have a corresponding radio-frequency phase and magnitude controller  62  (e.g., a first phase and magnitude controller  62 - 1  interposed on transmission line path  64 - 1  may control phase and magnitude for radio-frequency signals handled by antenna  40 - 1 , a second phase and magnitude controller  62 - 2  interposed on transmission line path  64 - 2  may control phase and magnitude for radio-frequency signals handled by antenna  40 - 2 , an Nth phase and magnitude controller  62 -N interposed on transmission line path  64 -N may control phase and magnitude for radio-frequency signals handled by antenna  40 -N, etc.). 
     Phase and magnitude controllers  62  may each include circuitry for adjusting the phase of the radio-frequency signals on transmission line paths  64  (e.g., phase shifter circuits) and/or circuitry for adjusting the magnitude of the radio-frequency signals on transmission line paths  64  (e.g., power amplifier and/or low noise amplifier circuits). Phase and magnitude controllers  62  may sometimes be referred to collectively herein as beam steering circuitry (e.g., beam steering circuitry that steers the beam of radio-frequency signals transmitted and/or received by phased antenna array  60 ). 
     Phase and magnitude controllers  62  may adjust the relative phases and/or magnitudes of the transmitted signals that are provided to each of the antennas in phased antenna array  60  and may adjust the relative phases and/or magnitudes of the received signals that are received by phased antenna array  60  from external equipment. Phase and magnitude controllers  62  may, if desired, include phase detection circuitry for detecting the phases of the received signals that are received by phased antenna array  60  from external equipment. The term “beam” or “signal beam” may be used herein to collectively refer to wireless signals that are transmitted and received by phased antenna array  60  in a particular direction. The term “transmit beam” may sometimes be used herein to refer to wireless radio-frequency signals that are transmitted in a particular direction whereas the term “receive beam” may sometimes be used herein to refer to wireless radio-frequency signals that are received from a particular direction. 
     If, for example, phase and magnitude controllers  62  are adjusted to produce a first set of phases and/or magnitudes for transmitted millimeter wave signals, the transmitted signals will form a millimeter wave frequency transmit beam as shown by beam  66  of  FIG. 3  that is oriented in the direction of point A. If, however, phase and magnitude controllers  62  are adjusted to produce a second set of phases and/or magnitudes for the transmitted millimeter wave signals, the transmitted signals will form a millimeter wave frequency transmit beam as shown by beam  68  that is oriented in the direction of point B. Similarly, if phase and magnitude controllers  62  are adjusted to produce the first set of phases and/or magnitudes, wireless signals (e.g., millimeter wave signals in a millimeter wave frequency receive beam) may be received from the direction of point A as shown by beam  66 . If phase and magnitude controllers  62  are adjusted to produce the second set of phases and/or magnitudes, signals may be received from the direction of point B, as shown by beam  68 . 
     Each phase and magnitude controller  62  may be controlled to produce a desired phase and/or magnitude based on a corresponding control signal  58  received from control circuitry  16  of  FIG. 2  or other control circuitry in device  10  (e.g., the phase and/or magnitude provided by phase and magnitude controller  62 - 1  may be controlled using control signal  58 - 1 , the phase and/or magnitude provided by phase and magnitude controller  62 - 2  may be controlled using control signal  58 - 2 , etc.). If desired, control circuitry  16  may actively adjust control signals  58  in real time to steer the transmit or receive beam in different desired directions over time. Phase and magnitude controllers  62  may provide information identifying the phase of received signals to control circuitry  16  if desired. 
     When performing millimeter or centimeter wave communications, radio-frequency signals are conveyed over a line of sight path between phased antenna array  60  and external equipment. If the external equipment is located at location A of  FIG. 3 , phase and magnitude controllers  62  may be adjusted to steer the signal beam towards direction A. If the external equipment is located at location B, phase and magnitude controllers  62  may be adjusted to steer the signal beam towards direction B. In the example of  FIG. 3 , beam steering is shown as being performed over a single degree of freedom for the sake of simplicity (e.g., towards the left and right on the page of  FIG. 3 ). However, in practice, the beam is steered over two or more degrees of freedom (e.g., in three dimensions, into and out of the page and to the left and right on the page of  FIG. 3 ). 
     During communications, an external object such as external object  56  may be present in the vicinity of device  10 . External object  56  may, for example, be a part of a user&#39;s body or clothing, a desktop, table, or other furniture, or other types of object external to device  10 . As external object  56  moves within a particular distance of phased antenna array  60  such as to a location  54 , external object  56  may block radio-frequency signals handled by phased antenna array  60 . In some scenarios, phased antenna array  60  may steer the beam of radio-frequency signals around external object  56  so that object  56  no longer blocks the beam. However, if object  56  is relatively large or if object external  56  moves too close to phased antenna array  60 , phased antenna array  60  may be unable to steer around external object  56 . 
     In addition, government regulations or industry standards may impose limits on emitted radiation levels from devices such as device  10 . These regulations or standards, which may include specific absorption rate (SAR) standards or other standards, impose maximum energy absorption limits or maximum power density limits on devices that are used in the vicinity of a user&#39;s body. Millimeter wave signals handled by phased antenna array  60  typically involve relatively high transmit power levels in order to maintain a satisfactory wireless link quality over a line of sight. When a user&#39;s body (e.g., external object  56  of  FIG. 3 ) approaches within a particular distance of phased antenna array  60  (e.g., at location  54 ), external object  56  may undesirably absorb more wireless energy than is otherwise permitted by the maximum energy absorption or maximum power density limits. There is therefore a tension between ensuring adequate wireless performance and satisfying industry or government standards. 
     In order to satisfy these standards without sacrificing wireless performance, device  10  may steer the beam away from external object  56  or may switch a different phased antenna array into use (e.g., a phased antenna array located at a different location  8  as shown in  FIG. 1 ) when external object  56  is near to phased antenna array  60 . Electronic device  10  may use sensor circuitry in input-output devices  20  of  FIG. 2  (e.g., capacitive proximity sensor circuitry, light sensor circuitry, image sensor circuitry, etc.) to detect the presence of external object  56  if desired. However, in practice, detecting external object  56  using these sensors may consume excessive processing resources in device  10 , may require additional hardware that consumes valuable real estate in device  10 , and/or may have limited external object detection accuracy. If desired, phased antenna array  60  may perform external object proximity detection to detect whether external objects such as external object  56  of  FIG. 3  are adjacent to phased antenna array  60  (e.g., to detect whether external object  56  has moved within a predetermined distance of phased antenna array  60  such as at location  54 ). For example, phased antenna array  60  may detect the proximity of external object  56  by transmitting radio-frequency signals using a first set of the antennas  40  in phased antenna array  60  and receiving the transmitted radio-frequency signals using a second set of the antennas  40  in phased antenna array  60 . The transmitted and received radio-frequency signals may be processed by control circuitry  16  ( FIG. 2 ) to determine the proximity of external object  56  relative to phased antenna array  60 . 
     A schematic diagram of an antenna  40  that may be formed in phased antenna array  60  (e.g., as antenna  40 - 1 ,  40 - 2 ,  40 - 3 , and/or  40 -N in phased antenna array  60 ) is shown in  FIG. 4 . As shown in  FIG. 4 , antenna  40  may be coupled to transceiver circuitry  30  (e.g., transceiver circuitry  28  of  FIG. 2 ). Transceiver circuitry  30  may be coupled to antenna feed  100  of antenna  40  using transmission line path  64 . Antenna feed  100  may include a positive antenna feed terminal such as positive antenna teed terminal  96  and may include a ground antenna feed terminal such as ground antenna feed terminal  98 . Transmission line path  64  may include a positive transmission line signal path such as path  94  that is coupled to terminal  96  and a ground transmission line signal path such as path  90  that is coupled to terminal  98 . 
     Any desired antenna structures may be used for implementing antenna  40 . In one suitable arrangement that is sometimes described herein as an example, patch antenna structures may be used for implementing antenna  40 . Antennas  40  that are implemented using patch antenna structures may sometimes be referred to herein as patch antennas. An illustrative patch antenna that may be used in phased antenna array  60  of  FIG. 3  is shown in  FIG. 5 . 
     As shown in  FIG. 5 , antenna  40  may have a patch antenna resonating element  104  that is separated from and parallel to a ground plane such as antenna ground  92 . Patch antenna resonating element  104  may lie within a plane such as the X-Y plane of  FIG. 5  (e.g., the lateral surface area of element  104  may lie in the X-Y plane). Patch antenna resonating element  104  may sometimes be referred to herein as patch  104 , patch element  104 , patch resonating element  104 , antenna resonating element  104 , or resonating element  104 . Antenna ground  92  may lie within a plane that is parallel to the plane of patch  104 . Patch  104  and antenna ground  92  may therefore lie in separate parallel planes that are separated by a distance  99 . Patch  104  and antenna ground  92  may be formed from conductive traces patterned on a dielectric substrate such as a rigid or flexible printed circuit board substrate, metal foil, stamped sheet metal, electronic device housing structures, or any other desired conductive structures. 
     The length of the sides of patch  104  may be selected so that antenna  40  resonates at a desired operating frequency. For example, the sides of patch  104  may each have a length L 1  that is approximately equal to half of the wavelength of the signals conveyed by antenna  40  (e.g., the effective wavelength given the dielectric properties of the materials surrounding patch  104 ). In one suitable arrangement, length L 1  may be between 0.8 mm and 1.2 mm (e.g., approximately 1.1 mm) for covering a millimeter wave frequency band between 57 GHz and 70 GHz, as just one example. 
     The example of  FIG. 5  is merely illustrative. Patch  104  may have a square shape in which all of the sides of patch  104  are the same length or may have a different rectangular shape. Patch  104  may be formed in other shapes having any desired number of straight and/or curved edges. If desired, patch  104  and antenna ground  92  may have different shapes and relative orientations. 
     To enhance the polarizations handled by antenna  40 , antenna  40  may be provided with multiple feeds. As shown in  FIG. 5 , antenna  40  may have a first feed at antenna port PV that is coupled to a first transmission line path  64  such as transmission line path  64 V and a second feed at antenna port PH that is coupled to a second transmission line path  64  such as transmission line path  64 H. The first antenna feed may have a first ground feed terminal coupled to antenna ground  92  (not shown in  FIG. 5  for the sake of clarity) and a first positive feed terminal  96 V coupled to patch  104 . The second antenna feed may have a second ground feed terminal coupled to ground plane  92  (not shown in  FIG. 5  for the sake of clarity) and a second positive feed terminal  96 H coupled to patch  104 . 
     Holes or openings such as openings may be formed in antenna ground  92  if desired. Transmission line path  64 V may include a vertical conductor (e.g., a conductive through-via, conductive pin, metal pillar, solder bump, combinations of these, or other vertical conductive interconnect structures) that extends through a hole (not shown) in antenna ground  92  to positive antenna feed terminal  96 V on patch  104 . Transmission line path  64 H may include a vertical conductor that extends through a hole (not shown) in antenna ground  92  to positive antenna feed terminal  96 H on patch  104 . This example is merely illustrative and, if desired, other transmission line structures may be used (e.g., coaxial cable structures, stripline transmission line structures, etc.). 
     When using the antenna feed associated with port PV (i.e., the antenna feed that includes positive antenna feed terminal  96 V), antenna  40  may transmit and/or receive radio-frequency signals having a first polarization (e.g., the electric field E 1  of antenna signals  102  associated with port PV may be oriented parallel to the Y-axis in  FIG. 5 ). When using the antenna feed associated with port PH (i.e., the antenna feed that includes positive antenna feed terminal  96 H), antenna  40  may transmit and/or receive radio-frequency signals having a second polarization (e.g., the electric field E 2  of antenna signals  102  associated with port PH may be oriented parallel to the X-axis of  FIG. 5  so that the polarizations associated with ports P 1  and P 2  are orthogonal to each other). 
     In scenarios such as these where the first polarization is linear and orthogonal to the second polarization (which is also linear), radio-frequency signals handled by port PV may sometimes be referred to herein as vertical polarization signals or vertically polarized signals whereas radio-frequency signals handled by port PH may sometimes be referred to herein as horizontal polarization signals or horizontally polarized signals. Transmission line path  64 V may therefore sometimes be referred to herein as vertical polarization transmission line path  64 V, positive antenna feed terminal  96 V may sometimes be referred to herein as vertical antenna feed terminal  96 V, and port PV may sometimes be referred to herein as vertical port PV. Similarly, transmission line path  64 H may therefore sometimes be referred to herein as horizontal polarization transmission line path  64 H, positive antenna feed terminal  96 H may sometimes be referred to herein as horizontal antenna feed terminal  96 H, and port PH may sometimes be referred to herein as horizontal port PH. The terms “vertical” and “horizontal” refer to the relative orientation between the signals handled by ports PH and PV (i.e., an orthogonal orientation) and do not refer to the relative orientation of the signals with respect to other components in device  10  or the surroundings of device  10 . 
     One of ports PV and PH may be used at a given time so that antenna  40  operates as a single-polarization antenna or both ports may be operated at the same time so that antenna  40  operates with other polarizations (e.g., as a dual-polarization antenna, a circularly-polarized antenna, an elliptically-polarized antenna, etc.). If desired, the active port may be changed over time so that antenna  40  can switch between covering vertical or horizontal polarizations at a given time. Ports PV and PH may be coupled to different phase and magnitude controllers  62  ( FIG. 3 ) or may both be coupled to the same phase and magnitude controller  62 . 
     The example of  FIG. 5  is merely illustrative and, if desired, antenna  40  may include any two antenna feeds having positive antenna feed terminals  96  coupled to patch  104  at any desired locations (e.g., regardless of polarization). If desired, antenna  40  may include one or more parasitic antenna resonating elements that serve to broaden the bandwidth of antenna  40  (e.g., where patch  104  is interposed between the parasitic antenna resonating element and antenna ground  92 ). Antenna  40  need not be a patch antenna and may be implemented as any other type of antenna if desired (e.g., an antenna having two feeds for covering two polarizations). 
     If desired, each antenna  40  in phased antenna array  60  ( FIG. 3 ) may be provided with two feeds as shown in  FIG. 5 . The phased antenna array  60  may be controlled by control circuitry  16  ( FIG. 2 ) to perform external object proximity detection operations to detect the proximity (e.g., presence) of external object  56  ( FIG. 3 ) adjacent to phased antenna array  60 .  FIG. 6  is a circuit diagram showing how wireless communications circuitry  34  may be coupled to phased antenna array  60  for performing external object proximity detection. 
     As shown in  FIG. 6 , wireless communications circuitry  34  may include a first millimeter wave transceiver  28  such as vertical transceiver (TX/RX)  28 V and a second millimeter wave transceiver  28  such as horizontal transceiver  28 H. Transceiver  28 V may be coupled to control circuitry  16  over data path  110 . Transceiver  28 H may be coupled to control circuitry  16  over data path  112 . Control circuitry  16  may include applications processor circuitry for running operating system software or other software associated with the control and operation of device  10 . Baseband processor circuitry may be formed within control circuitry  16 , as a part of transceivers  28 V and  28 H, or between control circuitry  16  and transceivers  28 V and  28 H. 
     If desired, control circuitry  16 , vertical transceiver  28 V, and horizontal transceiver  28 H may each be formed on separate substrates such as separate integrated circuits, integrated circuit packages, chips, or printed circuit boards. In another suitable arrangement, two or more of control circuitry  26 , vertical transceiver  28 V, and horizontal transceiver  28 H may be formed on the same substrate such as a shared integrated circuit, integrated circuit package, chip, or printed circuit board. 
     Vertical transceiver  28 V and horizontal transceiver  28 H may each include digital-to-analog converter circuitry, analog-to-digital converter circuitry, power amplifier circuitry, low noise amplifier circuitry, mixer circuitry (e.g., up-converter and down-converter circuitry), or other circuitry for generating and receiving radio-frequency signals at frequencies between 10 GHz and 300 GHz. If desired, additional mixing circuitry may be formed on data paths  110  and  112  for converting baseband data generated by baseband processor circuitry in control circuitry  16  to an intermediate frequency greater than a baseband frequency and less than 10 GHz. Conveying signals across device  10  at intermediate frequencies may, for example, involve less path loss than conveying signals across device  10  at frequencies greater than 10 GHz. 
     Phased antenna array  60  may include multiple antennas  40  each having multiple antenna feeds for covering different polarizations (e.g., vertical antenna feeds having vertical antenna feed terminals  96 V and horizontal antenna feeds having horizontal antenna feed terminals  96 H as shown in  FIG. 5 ). In the example of  FIG. 6 , phased antenna array  60  includes four antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4 . Antenna  40 - 1  may include a vertical antenna feed having a vertical antenna feed terminal  96 - 1 V and a horizontal antenna feed having a horizontal antenna feed terminal  96 - 1 H. Antenna  40 - 2  may include a vertical antenna feed having a vertical antenna feed terminal  96 - 2 V and a horizontal antenna feed having a horizontal antenna feed terminal  96 - 2 H. Antenna  40 - 3  may include a vertical antenna feed having a vertical antenna feed terminal  96 - 3 V and a horizontal antenna feed having a horizontal antenna feed terminal  96 - 3 H. Antenna  40 - 4  may include a vertical antenna feed having a vertical antenna teed terminal  96 - 4 V and a horizontal antenna feed having a horizontal antenna feed terminal  96 - 4 H. This example is merely illustrative and, in general, phased antenna array  60  may include any desired number of antennas arranged in any desired pattern. The antennas in phased antenna array  60  of  FIG. 6  may include any desired number of antenna feeds at any desired number of locations for covering radio-frequency signals with one or more different polarizations. Vertical transceiver  28 V may handle radio-frequency signals conveyed by vertical antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V, and  96 - 4 V of phased antenna array  60 . Horizontal transceiver  28 H may handle radio-frequency signals conveyed by horizontal antenna feed terminals  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H of phased antenna array  60 . 
     The antenna feeds in phased antenna array  60  may be coupled to switching circuitry  126  over respective transmission line paths (e.g., transmission line paths  64 H and  64 V as shown in  FIG. 5 ). As shown in  FIG. 6 , transmission line path  64 - 1 V may be coupled between switching circuitry  126  and vertical antenna feed terminal  96 - 1 V of antenna  40 - 1 , transmission line path  64 - 1 H may be coupled between switching circuitry  126  and horizontal antenna feed terminal  96 - 1 H of antenna  40 - 1 , transmission line path  64 - 2 V may be coupled between switching circuitry  126  and vertical antenna feed terminal  96 - 2 V of antenna  40 - 2 , transmission line path  64 - 1 H may be coupled between switching circuitry  126  and horizontal antenna feed terminal  96 - 2 H of antenna  40 - 2 , transmission line path  64 - 3 V may be coupled between switching circuitry  126  and vertical antenna feed terminal  96 - 3 V of antenna  40 - 3 , etc. 
     Respective phase and magnitude controllers (e.g., phase and magnitude controllers  62  as shown in  FIG. 3 ) may be interposed on each transmission line path  64 . As shown in  FIG. 6 , phase and magnitude controller  62 - 1 V may be interposed on transmission line path  64 - 1 V, phase and magnitude controller  62 - 1 H may be interposed on transmission line path  64 - 1 H, phase and magnitude controller  62 - 2 V may be interposed on transmission line path  64 - 2 V, phase and magnitude controller  62 - 2 H may be interposed on transmission line path  64 - 2 H, phase and magnitude controller  62 - 3 V may be interposed on transmission line path  64 - 3 V, etc. Each of the phase and magnitude controllers may be controlled by control signals received from control circuitry  16 . This example is merely illustrative. If desired, the same phase and magnitude controller may be interposed on two or more transmission line paths. In general, any desired transmission line structures may be used. 
     Switching circuitry  126  may include any desired switch network of any desired number of switches arranged in any desired manner. In one suitable example, switching circuitry  126  may be a switch matrix having a first port  122  and a second port  124 . As shown in  FIG. 6 , first port  122  of switching circuitry  126  may be coupled to horizontal transceiver  28 H over path  114 . Second port  124  of switching circuitry  126  may be coupled to vertical transceiver  28 V over path  116 . 
     Control circuitry  16  may control the state of switching circuitry  126  using control signals CTRL provided over control path  128 . Control signals CTRL may control switching circuitry  126  to selectively activate a desired set of antenna feeds in phased antenna array  60  at any given time. For example, control signals CTRL may control switching circuitry  126  to activate a selected number of vertical antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V, and  96 - 4 V (e.g., by coupling those antenna feed terminals to port  124  and vertical transceiver  28 V) and to activate a selected number of horizontal positive antenna feed terminals  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H (e.g., by coupling those antenna feed terminals to port  122  and horizontal transceiver  28 H) at any given time. Similarly, control signals CTRL may deactivate a selected number of vertical antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V, and  96 - 4 V (e.g., by decoupling those antenna feed terminals from port  124 ) and a selected number of horizontal positive antenna feed terminals  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H (e.g., by decoupling those antenna feed terminals from port  122 ) at any given time. 
     Front end circuitry such as front end circuits  118  may be interposed on path  114  between horizontal transceiver  28 H and port  122 . Front end circuitry such as front end circuits  120  may be interposed on path  116  between vertical transceiver  28 V and port  124 . Front end circuits  118  and  120  may each include impedance matching circuitry, switching circuitry, filter circuitry, or any other desired radio-frequency front end components (e.g., networks of passive and/or active (adjustable) components such as resistors, inductors, and capacitors, etc.). If desired, front end circuits  118  and  120  may each include passive filtering circuitry such as duplexer circuitry, diplexer circuitry, low pass filter circuitry, high pass filter circuitry, bandpass filter circuitry, notch filter circuitry, impedance matching circuitry, etc. The filter circuitry in front end circuits  118  may, for example, isolate transmit and receive signals that are conveyed over respective transmit and receive ports on horizontal transceiver  28 H. Similarly, the filter circuitry in front end circuits  120  may isolate transmit and receive signals that are conveyed over respective transmit and receive ports on horizontal transceiver  28 V. If desired, filter circuitry for isolating transmit and receive signals may be formed elsewhere in wireless communications circuitry  34  such as between switching circuitry  126  and phase and magnitude controllers  62 , between phase and magnitude controllers  62  and antennas  40 , as a part of switching circuitry  126 , etc. In another suitable arrangement, path  114  may include multiple conductive lines for coupling one or more transmit ports and one or more receive ports of horizontal transceiver  28 H to switching circuitry  126 . Similarly, path  116  may include multiple conductive lines for coupling one or more transmit ports and one or more receive ports of vertical transceiver  28 V to switching circuitry  126  (e.g., filtering circuitry for isolating horizontal and receive ports may be omitted if desired). 
     In this way, control circuitry  16  may selectively activate different antenna feed terminals in phased antenna array  60  for either transmitting or receiving radio-frequency signals at any given time. For example, control circuitry  16  may provide control signals CTRL to switching circuitry  126  to selectively activate a desired number of vertical antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V, and  96 - 4 V for transmitting radio-frequency signals (e.g., by coupling those vertical antenna feed terminals to one or more transmit ports of vertical transceiver  28 V). Similarly, control signals CTRL may control switching circuitry  126  to selectively activate a desired number of vertical antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V, and  96 - 4 V for receiving radio-frequency signals (e.g., by coupling those vertical antenna feed terminals to one or more receive ports of vertical transceiver  28 V). One or more vertical antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V, and  96 - 4 V may be decoupled from vertical transceiver  28 V so that those vertical antenna feed terminals do not transmit or receive any radio-frequency signals if desired. 
     Control signals CTRL may also control switching circuitry  126  to selectively activate a desired number of horizontal antenna feed terminals  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H for transmitting radio-frequency signals (e.g., by coupling those horizontal antenna feed terminals to one or more transmit ports of horizontal transceiver  28 H). Similarly, control signals CTRL may control switching circuitry  126  to selectively activate a desired number of horizontal antenna feed terminals  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H for receiving radio-frequency signals (e.g., by coupling those horizontal antenna feed terminals to one or more receive ports of horizontal transceiver  28 H). One or more horizontal antenna feed terminals  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H may be decoupled from horizontal transceiver  28 H so that the horizontal antenna feed terminals do not transmit or receive any radio-frequency signals if desired. 
     Phase and magnitude controllers  62  (e.g., phase and magnitude controllers  62 - 1 V,  62 - 1 H,  62 - 2 V,  62 - 2 H, etc.) may be adjusted to steer the beam of radio-frequency signals handled by phased antenna array  60  (e.g., as shown in  FIG. 3 ). If desired, phase and magnitude controllers  62  may each include phase measurement circuitry that measures the phase of radio-frequency signals received over phased antenna array  60 . For example, phase and magnitude controller  62 - 1 V may measure the phase of radio-frequency signals received over antenna feed terminal  96 - 1 V (e.g., vertically polarized radio-frequency signals received by antenna  40 - 1 ), phase and magnitude controller  62 - 1 H may measure the phase of radio-frequency signals received over antenna feed terminal  96 - 1 H (e.g., horizontally polarized radio-frequency signals received by antenna  40 - 1 ), phase and magnitude controller  62 - 2 V may measure the phase of radio-frequency signals received over antenna feed terminal  96 - 2 V (e.g., vertically polarized radio-frequency signals received by antenna  40 - 2 ), etc. Phase and magnitude controllers  62  may pass the phase measurements to control circuitry  16 . Control circuitry  16  may store and process the phase measurements over time. If desired, phase measurement circuitry for measuring the phase of received radio-frequency signals may be located elsewhere in wireless communications circuitry  34  (e.g., on transmission line paths  64  separate from phase and magnitude controllers  62 , coupled to transmission line paths  64  via radio-frequency coupler circuitry, in switching circuitry  126 , on paths  114  and  116 , in transceivers  28 V and  28 H, etc.). 
     Antenna feed terminals in phased antenna array  60  that have been activated for transmitting radio-frequency signals (e.g., that have been coupled to corresponding transmit ports on transceivers  28 V and  28 H by switching circuitry  126 ) may sometimes be referred to herein as transmit antenna feed terminals. Antenna feed terminals in phased antenna array  60  that have been activated for receiving radio-frequency signals (e.g., that have been coupled to corresponding receive ports on transceivers  28 V and  28 H by switching circuitry  126 ) may sometimes be referred to herein as receive antenna feed terminals. 
     Control circuitry  16  may control phased antenna array  60  to transmit and receive radio-frequency signals over different combinations (permutations) of antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H over time. Control circuitry  16  may store phase measurements performed by wireless communications circuitry  34  (e.g., generated by phase and magnitude controllers  62 ) for each of these combinations of transmit and receive antenna feed terminals over time. The presence of external objects such as external object  56  of  FIG. 3  adjacent to phased antenna array  60  may affect (alter) the phase measurements obtained by wireless communications circuitry  34  relative to a free space scenario in which no external objects are adjacent to phased antenna array  60 . Control circuitry  16  may process the gathered phase measurements to detect the proximity of external objects relative to phased antenna array  60  (e.g., by comparing the phase measurements for the different combinations of transmit and receive antenna feed terminals to corresponding phase measurements gathered in a free space scenario). 
       FIG. 7  is a side view of phased antenna array  60  showing how the presence of external objects adjacent to phased antenna array  60  may affect the phases of received radio-frequency signals measured by wireless communications circuitry  34 . As shown in  FIG. 7 , antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may be formed on a dielectric substrate such as substrate  140 . Substrate  140  may be, for example, a rigid or printed circuit board or other dielectric substrate. Substrate  140  may include multiple stacked dielectric layers (e.g., multiple layers of printed circuit board substrate such as multiple layers of fiberglass-filled epoxy, multiple layers of ceramic substrate, etc.). Antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may be embedded within and/or mounted to a surface of substrate  140 . For example, antenna ground  92  and patch  104  ( FIG. 5 ) of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may be formed on different layers of substrate  140  and may be embedded within or formed at an exterior surface of substrate  140  if desired. 
     When a given antenna in phased antenna array  60  transmits radio-frequency signals, a portion of the transmitted radio-frequency signals may be received over the air at the other antennas in phased antenna array  60 . In a free space environment (e.g., in the absence of external object  56 ), the phase of the transmitted radio-frequency signal is offset from the phases of the received radio-frequency signals due to the non-zero distances between the antenna that transmitted the radio-frequency signals and the antennas that received the radio-frequency signals. 
     Consider an example in which antenna  40 - 1  transmits radio-frequency signals at a known phase φ. Some of the transmitted radio-frequency signals are received at antenna  40 - 2 , antenna  40 - 3 , and antenna  40 - 4 . Phase measurement circuitry coupled to antennas  40 - 2 ,  40 - 3 , and  40 - 4  may measure the phases of the transmitted radio-frequency signals as received at antennas  40 - 2 ,  40 - 3 , and  40 - 4 . The phases of the received signals may be different from phase φ because of the non-zero distance between antenna  40 - 1  and antennas  40 - 2 ,  40 - 3 , and  40 - 4 . Control circuitry  16  ( FIG. 6 ) may already have knowledge of phase φ (e.g., because control circuitry  16  controls the phase and magnitude controller coupled to antenna  40 - 1  when transmitting the radio-frequency signals at phase φ). Control circuitry  16  may compare known phase φ to the phases of the received signals measured for antennas  40 - 2 ,  40 - 3 , and  40 - 4  to generate respective phase difference values Δφ between the transmitted radio-frequency signals and radio-frequency signals received by each of antennas  40 - 2 ,  40 - 3 , and  40 - 4 . The antennas  40  in phased antenna that transmit radio-frequency signals for detecting the proximity of external object  56  may sometimes be referred to herein as transmit antennas whereas the antenna  40  that receive the transmitted radio-frequency signals for detecting the proximity of external object  56  may sometimes be referred to herein as receive antennas. 
     In a free space environment, phase difference values Δφ will have a predetermined magnitude based primarily on the spatial distance between the transmit and receive antennas. Control circuitry  16  may store predetermined phase difference values between each combination of transmit and receive antennas. The predetermined phase difference values (sometimes referred to herein as free space phase difference values) may be generated for device  10  during calibration of wireless communications circuitry  34  in a free space environment (e.g., during device manufacture and testing and before normal use by an end user of device  10 ). In general, the phase difference values may vary based on which particular combination of antenna feed terminals are used (e.g., antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H of  FIG. 6 ). If desired, control circuitry  16  may store predetermined (calibrated) phase difference values for each possible combination (or a subset of each possible combination) of transmit and receive antenna feed terminals in phased antenna array  60 . 
     In free space, antennas  40  in phased antenna array  60  may exhibit electromagnetic mutual couplings. For example, antennas  40 - 1  and  40 - 4  may exhibit a mutual coupling  146 , antennas  40 - 1  and  40 - 3  may exhibit a mutual coupling  144 , and antennas  40 - 1  and  40 - 2  may exhibit a mutual coupling  142 . In general, antennas that are closer together may exhibit stronger mutual coupling than antennas that are farther apart (e.g., mutual coupling  142  may be stronger than mutual coupling  144  which is stronger than mutual coupling  146 ). In general, each possible pair of antennas  40  in phased antenna array  60  exhibits a corresponding mutual coupling. 
     In the presence of external objects such as external object  56 , external object  56  may alter the electromagnetic mutual coupling between two or more antennas  40  in phased antenna array  60 . As external object  56  moves closer to device  10 , external object  56  may exhibit greater influence on the mutual coupling between antennas  40  in phased antenna array  60 . In general, the phase of the radio-frequency signals received by antennas  40 - 2 ,  40 - 3 , and  40 - 4  may be dependent upon the strength of mutual couplings  142 ,  144 , and  146 , respectively. As mutual couplings  142 ,  144 , and/or  146  are altered (e.g., as external object  56  approaches phased antenna array  60 ), the phases of the received radio-frequency signals measured for antennas  40 - 2 ,  40 - 3 , and/or  40 - 4  may change so that the phase differences between the received radio-frequency signals and the transmitted radio-frequency signals is different or greater than the phase differences in free space). 
     Control circuitry  16  may monitor the phase differences between the received radio-frequency signals and the transmitted radio-frequency signals to detect changes in phase difference that are indicative of changes in mutual couplings  142 ,  144 , and/or  146  and that are thus indicative of the proximity of external object  56  to phased antenna array  60  (e.g., the presence of external object  56  within a predetermined distance such as at location  54  adjacent to phased antenna array  60 ). For example, control circuitry  16  may compare current phase difference values measured by phased antenna array  60  to predetermined free space phase difference values that would be expected for phased antenna array  60  in the absence of external object  56 . If the difference between the current phase difference values and the free space phase difference values is excessive, control circuitry  16  may identify that external object  56  is adjacent to (e.g., within a predetermined distance of) phased antenna array  60 . In general, greater differences between the current phase difference values and the free space phase difference values may be indicative of closer external object proximities than lesser differences between the current phase difference values and the free space phase difference values. 
     The example of  FIG. 7  is merely illustrative. In general, external object  56  may alter mutual couplings between respective pairs of vertical and horizontal antenna feed terminals in phased antenna array  60 . Control circuitry  16  may control phased antenna array  60  to transmit the radio-frequency signals using one, two, or more than two antenna feeds on any desired antennas in phased antenna array  60 . Control circuitry  16  may control phased antenna array  60  to receive the transmitted radio-frequency signals and to measure phases of the received radio-frequency signals over one, two, or more than two antenna feeds on any desired antennas in phased antenna array  60 . Control circuitry  16  may cycle through different combinations vertical and/or horizontal antenna feeds for transmitting and receiving radio-frequency signals over time. Control circuitry  16  may monitor phase difference values between the antenna feeds for each of these combinations and may process the phase difference values to identify the proximity of external object  56  (e.g., by comparing the phase difference values to predetermined free space phase difference values). In this way, control circuitry  16  may use phased antenna array  60  itself to detect the proximity of external objects in real time. 
       FIG. 8  is a flow chart of illustrative steps that may be performed by electronic device  10  for performing external object proximity detection using phased antenna array  60 . At step  170 , device  10  may enter a proximity detection mode of operation. Device  10  may perform external object proximity detection while in the proximity detection mode of operation to determine whether an external object such as external object  56  ( FIGS. 3 and 7 ) is adjacent to within a predetermined distance of) device  10 . Device  10  may enter the proximity detection mode of operation upon device start up, from a standby mode of operation in which the device is powered on but not being actively used by a user, or from a communications mode of operation, as examples. 
     In the communications mode of operation, wireless communications circuitry  34  may transmit and receive radio-frequency signals using phased antenna array  60  ( FIG. 6 ). The radio-frequency signals may include communications data conveyed between device  10  and external wireless equipment. Wireless communications circuitry  34  may transmit the radio-frequency signals at a frequency between 10 GHz and 300 GHz. Wireless communications circuitry  34  may transmit the radio-frequency signals at an increased power level (e.g., a maximum power level of wireless communications circuitry  34 ). Transmitting the radio-frequency signals at the increased power level may ensure that a satisfactory wireless link quality is maintained between device  10  and the external wireless equipment. However, an external object adjacent to phased antenna array  60  may be subject to excessive radio-frequency power density, particularly at the increased power level associated with the communications mode of operation. 
     In the proximity detection mode of operation, wireless communications circuitry  34  may continue to transmit radio-frequency signals that convey communications data for external wireless equipment or may transmit radio-frequency signals that do not convey any communications data for external wireless equipment (e.g., radio-frequency test signals). Wireless communications circuitry  34  may transmit the radio-frequency signals at a reduced power level in the proximity detection mode of operation (e.g., a power level that is less than the increased power level used during the communications mode of operation). As examples, the reduced power level may be 5 dB less than the increased power level used during the communications mode of operation, may be between 5 dB and 10 dB less than the increased power level, may be between 10 dB and 15 dB less than the increased power level, may be between 5 dB and 20 dB less than the increased power level, may be more than 20 dB less than the increased power level, may be between 3 dB and 5 dB less than the increased power level, may be 13 dB less than the power level, etc. The reduced power level may help to minimize wireless power density and thus any possible absorption by external objects that could be adjacent to phased antenna array  60  during the proximity detection mode of operation. 
     Device  10  may enter the proximity detection mode of operation from the communication mode of operation periodically or in response to a software trigger (e.g., a trigger in an application or software running on control circuitry  16 , a software trigger generated in response to a user input to device  10 , a software trigger issued at a predetermined time, a software trigger generated in response to sensor circuitry from sensor circuitry on device  10  such as sensor data that identifies that an external object may be adjacent to phased antenna array  60 , a software trigger received from external wireless equipment, etc.). Device  10  may detect the proximity (e.g., presence or absence) of external objects such as external object  56  ( FIGS. 3 and 7 ) while in the proximity detection mode of operation. 
     At step  172 , wireless communications circuitry  34  may transmit radio-frequency signals at the reduced power level using a first set of antenna feeds (a first set of antenna feed terminals) in phased antenna array  60 . In the example of  FIG. 6 , control circuitry  16  may control switching circuitry  126  so that a first set of antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H is coupled to corresponding transmit ports on transceivers  28 H and/or  28 V. The first set of antenna feed terminals may include one vertical antenna feed terminal such as vertical antenna feed terminal  96 - 1 V, one horizontal antenna feed terminal such as horizontal antenna feed terminal  96 - 3 H, multiple vertical antenna feed terminals such as vertical antenna teed terminals  96 - 1 V and  96 - 2 V, multiple horizontal antenna feed terminals such as horizontal antenna feed terminals  96 - 4 H and  96 - 1 H, or a combination of horizontal and vertical antenna feed terminals such as antenna feed terminals  96 - 1 V and  96 - 1 H (as examples). In general, the first set of antenna feed terminals may include any desired combination of one or more of antenna feeds  96 - 1 V,  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H. 
     Control circuitry  16  may control phase and magnitude controllers  62  so that the first set of antenna feed terminals transmits the radio-frequency signals using known phases. In a scenario where the first set of antenna feed terminals includes only antenna teed terminal  96 - 1 V, control circuitry  16  may control phase and magnitude controllers  62  so that antenna feed terminal  96 - 1 V transmits the radio-frequency signals with a selected (known) phase φ, as an example. 
     As shown in  FIG. 8 , at step  174 , wireless communications circuitry  34  may receive the radio-frequency signals transmitted by the first set of antenna feed terminals using a second set of antenna feeds (a second set of antenna feed terminals) in phased antenna array  60 . The second set of antenna feed terminals may include antenna feed terminals in phased antenna array  60  that are not included in the first set of antenna feed terminals (e.g., the first and second sets may be mutually exclusive). In the example of  FIG. 6 , control circuitry  16  may control switching circuitry  126  so that a second set of antenna feed terminals  96 - 1 V,  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H is coupled to corresponding receive ports on transceivers  28 H and/or  28 V. The first set of antenna feed terminals may include one vertical antenna feed terminal such as vertical antenna teed terminal  96 - 1 V, one horizontal antenna feed terminal such as horizontal antenna feed terminal  96 - 2 H, multiple vertical antenna feed terminals such as vertical antenna feed terminals  96 - 3 V and  96 - 2 V, multiple horizontal antenna feed terminals such as horizontal antenna feed terminals  96 - 2 H and  96 - 3 H, or a combination of horizontal and vertical antenna feed terminals such as antenna feed terminals  96 - 2 V and  96 - 1 H (as examples). In one particular example, the second set of antenna feed terminals may include all of the remaining antenna feed terminals in phased antenna array  60  that were not included in the first set of antenna feed terminals (e.g., the second set of antenna feed terminals may include antenna feed terminals  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H in the scenario where the first set of antenna feed terminals includes only antenna feed terminal  96 - 1 V). In general, the first set of antenna feed terminals may include any desired combination of one or more of antenna feeds  96 - 1 V,  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H. 
     Returning to  FIG. 8 , at step  176 , phase measurement circuitry in wireless communications circuitry  34  (e.g., phase measurement circuitry in phase and magnitude controllers  62  of  FIGS. 3 and 6 ) may measure the phases (e.g., may gather phase measurement values) of the radio-frequency signals received by the second set of antenna feed terminals. The phase measurement circuitry may pass the phase measurement values to control circuitry  16  for further processing. In the scenario where the first set of antenna feed terminals includes only antenna feed terminal  96 - 1 V and the second set includes all of the remaining antenna feed terminals of  FIG. 6 , control circuitry  16  may identify phase measurement values for the radio-frequency signals received by antenna feed terminals  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H. 
     Control circuitry  16  may generate phase difference values Δφ between each of the antenna feed terminals in the second set and each of the antenna feed terminals in the first set (e.g., by computing differences between the known phases of the transmitted signals and the phases measured for the received signals). For example, in the scenario where the first set of antenna feed terminals includes only antenna feed terminal  96 - 1 V and the second set includes all of the remaining antenna feed terminals of  FIG. 6 , control circuitry  16  may generate seven phase difference values Δφ, where each phase difference value is calculated by subtracting the known phase φ of the transmitted radio-frequency signals from the phase measurement values gathered from the radio-frequency signals received by antenna feed terminals  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H, respectively (e.g., a first phase difference value equal to the difference between the phase measurement value for antenna feed terminal  96 - 2 V and phase φ, a second phase difference value equal to the difference between the phase measurement value for antenna feed terminal  96 - 3 V and phase φ, a third phase difference value equal to the difference between the phase measurement value for antenna feed terminal  96 - 4 V and phase φ, etc.). 
     As another example, in a scenario where the first set of antenna feed terminals includes only antenna feed terminals  96 - 1 H and  96 - 1 V and the second set of antenna feeds includes only antenna feeds  96 - 4 H and  96 - 4 V, control circuitry  16  may generate four phase difference values Δφ (e.g., a first phase difference value equal to the difference between the known phase of the radio-frequency signals transmitted by antenna feed terminal  96 - 1 H and the phase measurement value gathered for antenna feed terminal  96 - 4 H, a second phase difference value equal to the difference between known phase of the radio-frequency signals transmitted by antenna feed terminal  96 - 1 H and the phase measurement value gathered for antenna feed terminal  96 - 4 V, a third phase difference value equal to the difference between the known phase of the radio-frequency signals transmitted by antenna feed terminal  96 - 1 V and the phase measurement value gathered for antenna feed terminal  96 - 4 H, and a fourth phase difference value equal to the difference between the known phase of the radio-frequency signals transmitted by antenna feed terminal  96 - 1 V and the phase measurement value gathered for antenna feed terminal  96 - 4 V). The generated phase difference values Δφ may be stored at control circuitry  16  for further processing. 
     At step  178 , control circuitry  16  may generate comparison data values Δφ′ by comparing the generated phase difference values Δφ to predetermined (e.g., calibrated) phase difference values stored at control circuitry  16 . The predetermined phase difference values stored at control circuitry  16  may sometimes be referred to herein as free space phase difference values ΔφFS. Free space phase difference values ΔφFS may, for example, be generated and stored at control circuitry  16  during calibration of wireless communications circuitry  34  or device  10  in a controlled free space environment in which no external objects such as external object  56  of  FIG. 7  are present. Control circuitry  16  may generate comparison data values Δφ (sometimes referred to herein collectively as comparison data) by subtracting phase difference values Δφ from the free space phase difference value ΔφFS generated for the same corresponding pair of antenna feed terminals. Control circuitry  16  may, for example, generate a respective free space phase difference value ΔφFS for each phase difference value Δφ generated at step  176 . 
     For example, in the scenario where the first set of antenna feed terminals includes only antenna feed terminal  96 - 1 V and the second set of antenna feed terminals includes antenna feed terminals  96 - 2 V,  96 - 3 V,  96 - 4 V,  96 - 1 H,  96 - 2 H,  96 - 3 H, and  96 - 4 H of  FIG. 6 , control circuitry  16  may generate seven comparison data values. The comparison data values may include a first comparison data value generated by subtracting the first phase difference value between antenna feed terminals  96 - 1 V and  96 - 2 V from a first free space phase difference value generated using the same antenna feed terminals  96 - 1 V and  96 - 2 V during device calibration, a second comparison data value generated by subtracting the second phase difference value generated between antenna feed terminals  96 - 1 V and  96 - 3 V from a second free space phase difference value generated using the same antenna feed terminals  96 - 1 V and  96 - 3 V during device calibration, etc. 
     In general, non-zero comparison data values may be indicative of a change in phase of the received radio-frequency signals relative to the transmitted radio-frequency signals, which may in turn be indicative in an alteration in mutual coupling between the antennas in phased antenna array  60  caused by the proximity of an external object (e.g., external object  56  of  FIG. 7 ). In general, greater comparison data values may be indicative of a larger and/or closer external object than lower comparison data values. Similarly, a greater number of non-zero comparison data values may be indicative of a larger and/or closer external object than a smaller number comparison data values. 
     At step  180 , control circuitry  16  may determine whether any sets of antenna feed terminals in phased antenna array  60  remain for characterization (e.g., whether any combinations of first and second sets of antenna feed terminals in phased antenna array  60  remain for characterization). If sets of antenna feed terminals remain for characterization, processing may proceed to step  184  as shown by path  182 . 
     At step  184 , control circuitry  16  may select new first and/or second sets of antenna feed terminals for characterization (e.g., new combinations of transmit and/or receive antenna feed terminals). Processing may subsequently loop back to step  172  as shown by path  186  to generate comparison data Δφ for phased antenna array  60  using the selected new first and/or second sets of antenna feeds. 
     For example, in the scenario where the first set of antenna feed terminals includes only antenna feed terminal  96 - 1 V and the second set of antenna feed terminals includes the remaining antenna feed terminals of  FIG. 6 , the new first set of antenna feed terminals may include only antenna feed terminal  96 - 2 V and the second set of antenna feed terminals may include the remaining antenna feed terminals in phased antenna array  60 . In this way, control circuitry  16  may cycle through different transmit antenna feed terminals during each iteration of steps  172 - 184 . As other examples, the first set of antenna feed terminals (as selected at step  184  or during the first iteration of step  172 ) may include each of the vertical antenna feed terminals whereas the second set of antenna feed terminals (as selected at step  184  or during the first iteration of step  174 ) may include each of the horizontal antenna feed terminals, the first set may include each of the horizontal antenna feed terminals whereas the second set includes each of the vertical antenna feed terminals, the first set may include both antenna feed terminals for one antenna in phased antenna array  60  whereas the second set includes some or all of the remaining antenna feed terminals in phased antenna array  60 , the first set may include all of the horizontal antenna feed terminals in phased antenna array  60  whereas the second set includes only one of the vertical antenna feed terminals in phased antenna array  60 , the first set may include only one horizontal antenna feed terminal in phased antenna array  60  whereas the second set includes only one vertical antenna feed terminal in phased antenna array  60 , etc. In general, the first and seconds sets for each iteration of steps  172 - 180  may include any desired combinations of the antenna feed terminals in phased antenna array  60  for transmitting or receiving the radio-frequency signals. 
     In this way, control circuitry  16  may cycle through multiple different combinations of transmit antenna feed terminals (i.e., antenna feed terminals used in the first set) and receive antenna feed terminals antenna feed terminals used in the second set) in phased antenna array  16  while gathering phase difference values and comparison data values for each combination. This may, for example, allow control circuitry  16  to fully characterize the electromagnetic mutual coupling between different combinations of antennas  40  across phased antenna array  60  (e.g., for detecting the proximity of external object  56  regardless of the precise size or orientation/location of external object  56  relative to phased antenna array  60 ). Control circuitry  16  may, for example, iterate through steps  172  through  180  for every possible combination of transmit and receive antenna feed terminals in phased antenna array  60  (e.g., given the number of total antenna feed terminals in phased antenna array  60 ) or may perform these steps for only a subset of every possible combination of transmit and receive antenna feed terminals (e.g., a minimum number of combinations needed to identify the proximity of external object  56  with satisfactory accuracy). When no sets of antenna feed terminals remain, processing may proceed to step  190  as shown by path  188 . 
     At step  190 , control circuitry may determine whether predetermined conditions have been satisfied for each of the combinations of first and second sets of antenna feed terminals (e.g., for each iteration of steps  172  through  180 ) based on the measured phase difference values Δφ and/or the generated comparison data Δφ′. 
     As one example, control circuitry  16  may compare each generated comparison data value Δφ′ to a predetermined maximum threshold value. If each of the comparison data values (or a sufficiently small number of the comparison data values) is less than the predetermined maximum threshold value, control circuitry  16  may determine that the predetermined condition is satisfied. Relatively small comparison data values may, for example, be indicative of the wireless performance of phased antenna array  60  being sufficiently similar to a free space scenario, such that control circuitry  16  possesses relatively high confidence that there are no external objects present adjacent to (e.g., within a predetermined distance of) phased antenna array  60 . In another suitable arrangement, control circuitry  16  may determine that the predetermined condition is satisfied if an average or other linear combination of the generated comparison data values is less than the predetermined maximum threshold value. 
     In this example, if one or more of the comparison data values exceeds the predetermined maximum threshold value, control circuitry  16  may determine that the predetermined condition is unsatisfied. An excessively large comparison data value may be indicative of a relatively large phase difference between the corresponding transmit and receive antenna feed terminals relative to the free space environment and thus a relatively large perturbation in the electromagnetic mutual coupling between those transmit and receive antenna feed terminals. Such a perturbation may be indicative of the presence of external object  56  within a predetermined distance from phased antenna array  60  (e.g., at a location  54  adjacent to phased antenna array  60  as shown in  FIG. 7 ) 
     In another suitable example, control circuitry  16  may determine that predetermined condition is unsatisfied if a selected number of the comparison data values exceed the predetermined maximum threshold value. In another suitable arrangement, control circuitry  16  may determine that the predetermined condition is unsatisfied if a combination (e.g., an average, sum, linear combination, etc.) of the generated comparison data values exceed the predetermined maximum threshold value. The comparison data that is compared to the maximum threshold value may include comparison data generated from one combination of first and second sets of antenna feed terminals (e.g., one iteration of steps  172 - 180 ) or from multiple combinations of first and second sets of antenna feed terminals (e.g., multiple iterations of steps  172 - 180 ). 
     If desired, control circuitry  16  may combine other sensor data (e.g., impedance sensor data, capacitive proximity sensor data, image sensor data, light sensor data, etc.) with the measured phase difference values and/or the generated comparison data values to determine whether the predetermined conditions are satisfied. These examples are merely illustrative and, in general, any desired combination of the data gathered while processing one or more iterations of one or more of steps  172 - 180  may be compared to any desired predetermined conditions to determine whether an external object is in proximity to device  10 . If desired, step  178  may be omitted and control circuitry  16  may determine whether an external object is present using only phase difference values and/or sensor data. 
     If the predetermined conditions are unsatisfied, control circuitry  16  may determine that an external object such as external object  56  is adjacent to (in close proximity to) phased antenna array  60  and device  10  (e.g., within a predetermined distance of phased antenna array  60  such as at location  54  of  FIG. 7 ). Processing may subsequently proceed to step  194  as shown by path  192 . 
     At step  194 , control circuitry  16  may take appropriate action to ensure that satisfactory wireless communications are performed by wireless communications circuitry  34  while still satisfying industry or government requirements on absorbed radiation. For example, control circuitry  16  may disable phased antenna array  60  and may switch a different phased antenna array on device  10  into use (e.g., a phased antenna array pointed away from the detected external object). As another example, control circuitry  16  may steer phased antenna array  90  to a different location (e.g., so that the beam of signals handled by phased antenna array  60  is steered around the detected external object). If desired, control circuitry  16  may switch phased antenna array  60  out of use and may switch a different phased antenna array into use in response to determining that phased antenna array  60  is incapable of steering around the detected external object (e.g., in scenarios where the external object is relatively large or located too close to phased antenna array  60 ). In this scenario, control circuitry  16  may compare the generated comparison data values to first and second threshold values, for example. If the comparison data values exceed the first threshold value but not the second threshold value, this may be indicative of external object  56  being located close enough to phased antenna array  60  that beam steering away from the external object is required but not close enough that phased antenna array  60  needs to be disabled. If the comparison data values exceed the second threshold value, this may be indicative of external object  56  being located too close to phased antenna array  60  to steer around the external object and phased antenna array  60  may be disabled. Other suitable actions may be taken if desired. For example, control circuitry  16  may disable communications at frequencies greater than 10 GHz, may issue an alert to a user of device  10 , may issue an alert to other devices, etc. 
     Phased antenna array  60  may perform object detection using radio-frequency signals transmitted at the reduced power level because the radio-frequency signals need not be conveyed to external wireless equipment and need only be received by other antennas that are within the same antenna array and thus in close proximity to the transmit antennas. The reduced power level may help to ensure that device  10  continues to satisfy government and industry standards on absorbed radiation even if external object  56  (e.g., part of the user&#39;s body) is present adjacent to phased antenna array  60 . If desired, processing may loop back to step  170  after a predetermined amount of time or periodically so that phased antenna array  60  may determine whether the external object is still adjacent to phased antenna array  60  or whether the external object has moved away from device  10 . 
     If the predetermined conditions are satisfied while processing step  190 , control circuitry  16  may determine that no external objects are adjacent to phased antenna array  60  (e.g., that any potential external objects are farther than a predetermined distance away from device  10 ). Processing may subsequently proceed to step  198  as shown by path  196 . 
     At step  198 , control circuitry  16  may enter the wireless communications mode of operation. Control circuitry  16  may subsequently perform wireless communications using the increased transmit power level. For example, control circuitry  16  may exchange wireless data with external wireless equipment using greater transmit power levels than are used while in the proximity detection mode of operation. The increased transmit power level may allow phased antenna array  60  to maintain a satisfactory wireless link quality with the external wireless device. Because external objects are not located within the vicinity of phased antenna array  60 , phased antenna array  60  may perform wireless communications using the increased transmit power level while satisfying government and industry standards on absorbed radiation. If desired, processing may loop back to step  170  after a predetermined amount of time, periodically, or in response to a software trigger so that phased antenna array  60  may continue to monitor for the presence of external objects adjacent to phased antenna array  60  over time. In this way, phased antenna array  60  may maintain a satisfactory wireless link with external wireless equipment at frequencies greater than 10 GHz while still ensuring that government and industry standards on absorbed radiation are satisfied. Device  10  need not include other bulky or processing-intensive sensor circuitry for detecting the proximity of external objects with respect to phased antenna array  60 . 
     The example of  FIG. 8  is merely illustrative. In another suitable arrangement, control circuitry  16  may determine whether the predetermined conditions are satisfied for each combination of first and second sets of antenna feed terminals before a new combination of first and second sets is selected (e.g., steps  180  and  184  may be performed after step  190  of  FIG. 8  if desired). In this scenario, control circuitry  16  may proactively proceed to step  194  if an external object is detected using the phased differences and/or comparison data generated for a given combination of first and second sets of antenna feed terminals without expending further time or resources characterizing additional combinations of first and second sets. 
     Control circuitry  16  ( FIG. 6 ) may be configured to perform these operations (e.g., the operations of  FIG. 8 ) using hardware (e.g., dedicated hardware or circuitry) and/or software (e.g., code that runs on the hardware of device  10 ). Software code for performing these operations is stored on non-transitory computer readable storage media (e.g., tangible computer readable storage media). The software code may sometimes be referred to as software, data, program instructions, instructions, or code. The non-transitory computer readable storage media may include non-volatile memory such as non-volatile random-access memory (NVRAM), one or more hard drives (e.g., magnetic drives or solid state drives), one or more removable flash drives or other removable media, other computer readable media, or combinations of these computer readable media or other storage. Software stored on the non-transitory computer readable storage media may be executed on the processing circuitry of control circuitry  16 . The processing circuitry may include application-specific integrated circuits with processing circuitry, one or more microprocessors, or other processing circuitry. 
       FIG. 9  a table showing how phase difference values and comparison data values may be generated over time for phased antenna array  60  in one illustrative example. In the example of  FIG. 9 , the first set of antenna feed terminals includes only antenna feed terminal  96 - 1 V and the second set of antenna feed terminals includes only antenna feed terminals  96 - 2 V,  96 - 3 V, and  96 - 4 V. 
     Row  200  of  FIG. 9  shows free space phase difference values ΔφFS (in degrees) relative to antenna feed terminal  96 - 1 V, For example, in a free space environment (e.g., during calibration of device  10 ), antenna feed terminal  96 - 1 V exhibits a zero-degree phase difference with respect to itself, whereas antenna feed terminal  96 - 2 V exhibits a 20-degree phase difference, antenna feed terminal  96 - 3 V exhibits a 40-degree phase difference, and antenna feed terminal  96 - 4 V exhibits a 60-degree phase difference with respect to antenna feed terminal  96 - 1 V. 
     After device  10  has been manufactured and tested, device  10  may the enter proximity detection mode (e.g., while processing step  170  of  FIG. 8 ). Antenna feed terminal  96 - 1 V transmit radio-frequency signals with a known phase (e.g., while processing step  172  of  FIG. 8 ). Antenna feed terminals  96 - 2 V,  96 - 3 V, and  96 - 4 V may receive the transmitted radio-frequency signals (e.g., while processing step  174  of  FIG. 8 ). Control circuitry  16  may measure the phase of the radio-frequency signals received by antenna feed terminals  96 - 2 V,  96 - 3 V, and  96 - 4 V and may subtract the measured phases from the known phase of the radio-frequency signals transmitted by antenna feed terminal  96 - 1 V to obtain phase difference values  41  (row  202 ). In the example of  FIG. 9 , antenna feed terminal  96 - 1 V exhibits a zero-degree phase difference with respect to itself, whereas antenna feed terminal  96 - 2 V exhibits a 30-degree phase difference, antenna feed terminal  96 - 3 V exhibits a 40-degree phase difference, and antenna feed terminal  96 - 4 V exhibits a 60-degree phase difference with respect to antenna feed terminal  96 - 1 V. 
     Control circuitry  16  may compute the difference between the values in row  202  (i.e., the generated phase difference values) and the values in row  200  (i.e., the predetermined free space phase difference values) to generate comparison data values Δφ 1 ′ (row  204 ). As shown in row  204  of  FIG. 9 , control circuitry  16  may generate comparison data values of zero for each antenna feed terminal except for antenna feed terminal  96 - 2 V in this example, which exhibits 10 degrees of greater phase difference relative to antenna teed terminal  96 - 1 V than in the free space scenario. 
     If desired, control circuitry  16  may select a new combination of first and second sets of antenna feed terminals for characterization (e.g., while processing step  184  of  FIG. 8 ) and may continue to iterate through combinations of transmit and receive antenna feed terminals until control circuitry  16  detects an external object in adjacent to phased antenna array  60  (e.g., within a predetermined distance) or until control circuitry  16  determines that no external object is present adjacent to phased antenna array  60 . 
     In another suitable arrangement, control circuitry  16  may use the comparison data values in row  204  to determine whether predetermined conditions indicative of the absence of external object  56  have been satisfied (e.g., at step  190  of  FIG. 8  in scenarios where steps  180  and  184  are performed after step  190 ). In this scenario, control circuitry  16  may compare the information in row  204  to a maximum comparison data threshold value to determine whether an external object is located adjacent to phased antenna array  60  (e.g., while processing step  190  of  FIG. 8 ). In general, greater maximum comparison data threshold values may eliminate more false positives than lower maximum comparison data threshold values and lower maximum comparison data threshold values may be more sensitive to external objects than greater maximum comparison data threshold values. If 10 degrees is greater than the maximum threshold value, this may indicate the presence of external object  56  adjacent to (e.g., within a predetermined distance of) phased antenna array  60  (e.g., where external object  56  has sufficiently altered mutual coupling  142  between antennas  40 - 1  and  40 - 2  as shown in  FIG. 7 ). If control circuitry  16  detects the presence of external object  56  adjacent to phased antenna array  60 , a different phased antenna array may be used for communications (e.g., while processing step  194  of  FIG. 8 ). If 10 degrees is less than a maximum threshold value, control circuitry  16  may determine that no external object is present adjacent to phased antenna array  60  and the device may enter the communications mode of operation (e.g., while processing step  198  of  FIG. 8 ). 
     Once device  10  has been placed into the communications mode of operation, device  10  may return to the proximity detection mode of operation after a predetermined amount of time has passed so that phased antenna array  60  may continue to monitor its surroundings for the proximity of external objects (e.g., returning to step  170  of  FIG. 8 ). Row  206  of  FIG. 9  shows additional phase difference values Δφ 2  that may be generated by control circuitry  16  after device  10  has returned to the proximity detection mode of operation (e.g., assuming the first set of antenna feed terminals still includes only antenna feed terminal  96 - 1 V and the second set of antenna feed terminals still includes only antenna feed terminals  96 - 2 V,  96 - 3 V, and  96 - 4 V). In this iteration, the received radio-frequency signals may exhibit a greater phase difference for some of the antenna feeds than when the data in row  202  was generated (e.g., because external object  56  has moved closer to phased antenna array  60 ). For example, the radio-frequency signals received by antenna feed terminal  96 - 2 V may exhibit a phase difference of 40 degrees with respect to the transmitted radio-frequency signals and the radio-frequency signals received by antenna feed terminal  96 - 2 V may exhibit a phase difference of 50 degrees with respect to the transmitted radio-frequency signals. 
     Row  208  of  FIG. 9  shows comparison data values Δφ 2 ′ that control circuitry  16  may generate by subtracting the values in row  200  from the values in row  206 . As shown in row  208 , control circuitry  16  may generate comparison data values of zero for each antenna feed terminal except for antenna feed terminal  96 - 2 V, which exhibits 20 degrees of greater phase difference relative to antenna feed terminal  96 - 1 V than in free space, and antenna feed terminal  96 - 3 V, which exhibits 10 degrees of greater phase difference relative to antenna feed terminal  96 - 1 V than in free space. These values may be used to determine whether predetermined conditions indicative of the absence of external object  56  adjacent to phased antenna array  60  have been satisfied (e.g., while processing step  190  of  FIG. 8 ). 
     For example, if the predetermined maximum threshold value for comparison data is 15, control circuitry  16  may determine that the predetermined conditions are unsatisfied (i.e., because the comparison data value of 20 degrees associated with antenna feed terminal  96 - 2 V is greater than this threshold). Control circuitry  16  may therefore determine that an external object is located adjacent to phased antenna array  60 . If the predetermined conditions require a zero-degree comparison data value for antenna feed terminal  96 - 3 V, control circuitry  16  may also determine that an external object is located adjacent to phased antenna array  60  in this example. 
       FIG. 9  is a simplified example of one particular arrangement and is merely illustrative of some processing operations that may be performed while processing the steps of  FIG. 8 . In general, the first and second sets of antenna feed terminals may include any desired horizontal and/or vertical antenna feeds from phased antenna array  60 . The actual phase difference values shown in  FIG. 9  will typically vary in practice (e.g., based on the geometry of phased antenna array  60 , the frequencies used, environmental conditions, etc.). Any desired combination of the comparison data values shown in rows  202  and  208  may be compared to any desired predetermined conditions (e.g., one or more threshold values) to determine whether an external object has approached phased antenna array  60  within a predetermined distance (e.g., while processing stop  190  of  FIG. 8 ). Additional data such as sensor data may also be used to determine whether the predetermined conditions have been satisfied. Phased antenna array  60  may include any desired number of antennas each having any desired number of antenna feed terminals for handling radio-frequency signals of any desired polarizations. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20180227
Publication Date: 20201103
Grant Date: 20201103
Priority Date: 20180227
Inventors: MOW, MATTHEW A.
GOMEZ ANGULO, RODNEY A.
RAJAGOPALAN, HARISH
PAULOTTO, Simone
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q9/045", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01R29/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q3/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q3/28", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q21/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q3/267", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01R29/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q3/28", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q21/24", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 67686220