PATENT DOCUMENT

Publication Number: US-10547339-B2
Application Number: US-201715414287-A
Country: US
Kind Code: B2

Title: Electronic devices having millimeter wave wireless data transfer capabilities

Abstract:
An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas and first and second radio-frequency modules. The device may include a conductive housing having dielectric antenna windows. The first module may generate first millimeter wave signals in a first communications band. The antenna may transmit the first signals to external equipment through the dielectric window at a transmit power level. The antenna may receive control signals in the second communications band from the external equipment through the dielectric window. The first and second communications bands may include frequencies greater than 10 GHz. The second module may pass the received control signals to the first module to adjust the transmit power level of the first signals transmitted by the antenna. A duplexer may be interposed between the modules and the antenna for isolating the first and second communications bands.

Claims:
What is claimed is: 
     
       1. An electronic device that wirelessly communicates with an external electronic device, the electronic device comprising:
 a conductive housing; 
 a dielectric antenna window in the conductive housing; 
 a first radio-frequency transceiver that generates first Extremely High Frequency (EHF) signals in a first EHF band; 
 an antenna that transmits the first EHF signals to the external electronic device through the dielectric antenna window and that receives second EHF signals from the external electronic device through the dielectric antenna window, wherein the second EHF signals are in a second EHF band that is different from the first EHF band; 
 a second radio-frequency transceiver that receives the second EHF signals from the antenna; and 
 a duplexer having a first port coupled to the first radio-frequency transceiver, a second port coupled to the second radio-frequency transceiver, and a third port coupled to the antenna, wherein the duplexer is configured to isolate the first EHF signals from the second EHF signals, the antenna is configured to transmit the first EHF signals at a transmit power level, the antenna is configured to receive control signals from the external electronic device in the second EHF band, the second radio-frequency transceiver is configured to convey, via an inter-chip control path, the control signals received by the antenna to the first radio-frequency transceiver, and the first radio-frequency transceiver is configured to adjust the transmit power level based on the control signals. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the first radio-frequency transceiver is formed on a first radio-frequency module and the second radio-frequency transceiver is formed on a second radio-frequency module that is different from the first radio-frequency module. 
     
     
       3. The electronic device defined in  claim 1 , wherein the duplexer comprises a resonant waveguide structure. 
     
     
       4. The electronic device defined in  claim 1 , wherein the first and second EHF bands each comprise frequencies above 10 GHz. 
     
     
       5. The electronic device defined in  claim 4 , wherein the first EHF band comprises a 62.5 GHz frequency band and the second EHF band comprises a 58.5 GHz frequency band. 
     
     
       6. The electronic device defined in  claim 1 , the electronic device further comprising:
 processing circuitry configured to identify a link quality associated with the received second EHF signals and configured to generate the control signals based on the identified link quality, wherein the antenna is configured to transmit the control signals to the external electronic device through the dielectric antenna window in the first EHF band, and the transmitted control signals instruct the external electronic device to adjust the transmit power level of the second EHF signals. 
 
     
     
       7. The electronic device defined in  claim 1 , further comprising:
 an additional antenna, wherein the additional antenna is configured to transmit the first EHF signals to the external electronic device through the dielectric antenna window and is configured to receive the second EHF signals from the external electronic device through the dielectric antenna window. 
 
     
     
       8. The electronic device defined in  claim 1 , further comprising:
 a phased antenna array that includes the antenna; and 
 control circuitry, wherein the control circuitry is configured to control the phased antenna array to perform beam steering operations on the first EHF signals through the dielectric antenna window. 
 
     
     
       9. The electronic device defined in  claim 1 , further comprising:
 baseband processor circuitry coupled to an input of the first radio-frequency transceiver, wherein the baseband processor circuitry is configured to pass baseband signals corresponding to the first EHF signals to the first radio-frequency transceiver without performing any packetization of the baseband signals. 
 
     
     
       10. The electronic device defined in  claim 1 , further comprising:
 a display having a display cover layer, wherein the conductive housing comprises a planar rear surface for the electronic device that opposes the display cover layer, the conductive housing comprises sidewall structures extending from the planar rear surface to the display cover layer, and the dielectric antenna window is formed in an opening in the planar rear surface of the conductive housing. 
 
     
     
       11. The electronic device defined in  claim 1 , wherein the antenna is configured to transmit the first EHF signals at a transmit power level, the electronic device further comprising:
 control circuitry configured to adjust the transmit power level based on the second EHF signals received from the external electronic device. 
 
     
     
       12. The electronic device defined in  claim 11 , wherein the control circuitry is configured to determine whether a link quality associated with the received second EHF signals is satisfactory and, in response to identifying that the link quality associated with the received second EHF signals is unsatisfactory, generate a wireless control signal that identifies a power level adjustment for the external electronic device and transmit the wireless control signal to the external electronic device over the antenna in the first EHF band. 
     
     
       13. The electronic device defined in  claim 1 , further comprising:
 a baseband processor coupled to the first and second radio-frequency transceivers. 
 
     
     
       14. The electronic device defined in  claim 13 , wherein the baseband processor is configured to perform amplitude-shift keying (ASK) modulation on a stream of data to generate ASK modulated data, the baseband processor being further configured to provide the ASK modulated data to first radio-frequency transceiver. 
     
     
       15. The electronic device defined in  claim 14 , wherein the baseband processor is configured to perform ASK demodulation on an additional stream of data received from the second radio-frequency transceiver. 
     
     
       16. The electronic device defined in  claim 1 , wherein the second radio-frequency transceiver is configured to convey the control signals to the first radio-frequency transceiver over the inter-chip control path using an Inter-Chip Communication (ICC) protocol. 
     
     
       17. The electronic device defined in  claim 16 , wherein the first radio-frequency transceiver is formed on a first integrated circuit chip, the second radio-frequency transceiver is formed on a second integrated circuit chip that is different from the integrated circuit chip, the first radio-frequency transceiver comprises debugging circuitry, that is-configured to generate a pseudo-random sequence of test bits and is configured to inject the pseudo-random sequence of test bits onto the antenna for transmission to the external electronic device through the dielectric antenna window, the electronic device further comprising a baseband processor coupled to the first and second radio-frequency transceivers, the baseband processor is configured to provide a stream of data to the first radio-frequency transceiver without packetizing the stream of data, the baseband processor is configured to perform amplitude-shift keying (ASK) modulation on a stream of data to generate ASK modulated data, the baseband processor is configured to provide the ASK modulated data to first radio-frequency transceiver, and the baseband processor is configured to perform ASK demodulation on an additional stream of data received from the second radio-frequency transceiver. 
     
     
       18. An electronic device that wirelessly communicates with an external electronic device, the electronic device comprising:
 a conductive housing; 
 a dielectric antenna window in the conductive housing; 
 a first radio-frequency transceiver that generates first Extremely High Frequency (EHF) signals in a first EHF band; 
 an antenna that transmits the first EHF signals to the external electronic device through the dielectric antenna window and that receives second EHF signals from the external electronic device through the dielectric antenna window, wherein the second EHF signals are in a second EHF band that is different from the first EHF band; 
 a second radio-frequency transceiver that receives the second EHF signals from the antenna; 
 a duplexer having a first port coupled to the first radio-frequency transceiver, a second port coupled to the second radio-frequency transceiver, and a third port coupled to the antenna, wherein the duplexer is configured to isolate the first EHF signals from the second EHF signals, wherein the first radio-frequency transceiver comprises:
 debugging circuitry, the debugging circuitry being configured to generate a pseudo-random sequence of test bits and to inject the pseudo-random sequence of test bits onto the antenna for transmission to the external electronic device through the dielectric antenna window, wherein the antenna is configured to receive control signals in the second EHF band from the external electronic device, the external electronic device being configured to generate the control signals based on a link quality identified by the external electronic device based on the pseudo-random sequence of test bits; and 
 
 processing circuitry configured to adjust a transmit power level of the first EHF signals based on the control signals received from the external electronic device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of provisional patent application No. 62/289,092, filed Jan. 29, 2016, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with communications circuitry. 
     Electronic devices often use communications circuitry to transfer data to external devices. Conventional electronic devices include wired data ports such as Universal Serial Bus (USB) ports, Peripheral Component Interconnect Express (PCIe) ports, Thunderbolt ports, or any other desired ports for conveying data with an external device. The data conveyed over the wired data ports often includes large data files such as high definition video and audio data. The wired data ports allow for relatively high rates of data transfer (i.e., data rates of 1 bit per second or greater). The high data rates obtainable using wired data ports allows for large data files to be transferred to the external device in a relatively short amount of time. However, wired data ports can be bulky and occupy excessive space on the electronic device. 
     It would therefore be desirable to be able to provide electronic devices with improved data transfer capabilities. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may be used to handle millimeter wave wireless communications at frequencies of greater than or equal to 10 GHz. 
     The electronic device may include a conductive housing. If desired the device may include a non-conductive housing or a housing formed from a combination of conductive and non-conductive materials. A display having a display cover layer may be formed in the conductive housing. The conductive housing may include a rear planar surface that opposes the display cover layer. The conductive housing may include conductive sidewall structures that extend from the rear planar surface to the display cover layer. Dielectric antenna windows may be formed within openings in the rear surface of the conductive housing. The antennas may be mounted behind the dielectric antenna windows and may convey millimeter wave signals at Extremely High Frequencies (EHF) of greater than 10 GHz through the dielectric antenna windows. 
     The electronic device may include radio-frequency circuitry such as first and second radio-frequency modules. The first radio-frequency module may generate first millimeter wave signals in a first EHF communications band. The antenna may transmit the first millimeter wave signals to external equipment through a given one of the dielectric antenna windows at a transmit power level. The antenna may receive second millimeter wave signals in a second EHF communications band from the external equipment through the same dielectric antenna window or through an additional dielectric antenna window. The antenna may receive wireless control signals in the second EHF communications band from the external equipment through the dielectric antenna window. The first and second EHF communications bands may cover the same EHF frequencies or may cover different EHF frequencies. One or both of the EHF communications bands may, for example, be a 60 GHz communications band, a 62.5 GHz communications band, a 58.5 GHz communications band, or any other communications band above 10 GHz. 
     The electronic device may include a duplexer having a first port coupled to the first radio-frequency module, a second port coupled to the second radio-frequency module, and a third port coupled to the antennas. The duplexer may isolate signals on the first port from leaking onto the second port. The duplexer may pass the received second millimeter wave signals and the received wireless control signals to the second radio-frequency module. 
     The second radio-frequency module may pass the received wireless control signals to the first radio-frequency module to adjust the transmit power level of the first millimeter wave signals transmitted by the antenna. The second radio-frequency module may pass the second millimeter wave signals to control circuitry. The control circuitry may identify a link quality associated with the second millimeter wave signals by generating wireless performance metric data from the second millimeter wave signals. The control circuitry may identify transmit power level adjustments based on the identified link quality. The control circuitry may convey additional control signals identifying the transmit power level adjustments to the external equipment over the antenna. 
     In accordance with any of the above arrangements, the control circuitry may inject a pseudo random sequence of test bits onto the antenna for evaluating the wireless link quality associated with the first and/or second millimeter wave signals. 
     In accordance with any of the above arrangements, the antennas may be arranged in a phased antenna array that transmits the first millimeter wave signals. The control circuitry may control relative phases of the first millimeter wave signals provided to the phased antenna array to perform beam steering operations on the first millimeter wave signals transmitted through the dielectric antenna window. 
     In accordance with any of the above arrangements, the electronic device may include a single antenna for transmitting signals in the first EHF band through a given dielectric antenna window and for receiving signals in the second EHF band through that dielectric antenna window. 
     In accordance with any of the above arrangements, the electronic device may include first and second antennas and first and second dielectric antenna windows. The second antenna may receive the second millimeter wave signals and the wireless control signals through the second dielectric antenna window. The first antenna may transmit the first millimeter wave signals through the first dielectric antenna window. In this scenario, the first and second millimeter wave signals may be in the same EHF communications band. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device having wireless communications circuitry for communicating with an external device over millimeter wave communications links in accordance with an embodiment. 
         FIG. 2  is a perspective view of an electronic device having antennas for performing millimeter wave communications in accordance with an embodiment. 
         FIG. 3  is a block diagram of an illustrative radio-frequency communications module for performing millimeter wave communications in accordance with an embodiment. 
         FIG. 4  is a flow chart of illustrative steps that may be performed by first and second electronic devices for optimizing transmit power levels of millimeter wave communications links between the first and second electronic devices in accordance with an embodiment. 
         FIG. 5  is a flow chart of illustrative steps that may be performed by a radio-frequency communications module for evaluating the quality of a millimeter wave communications link using an injected test bit pattern in accordance with an embodiment. 
         FIG. 6  is a diagram showing how an illustrative electronic device may include respective antenna windows for handling millimeter wave communications links using multiple antennas in accordance with an embodiment. 
         FIG. 7  is a diagram showing how an illustrative electronic device may include a single antenna window for handling multiple millimeter wave communications links using a single antenna in accordance with an embodiment. 
         FIG. 8  is a diagram showing how an illustrative electronic device may include filtering circuitry for concurrently conveying millimeter wave signals in different millimeter wave bands over a single antenna and through a single antenna window in accordance with an embodiment. 
         FIG. 9  is a diagram showing how an illustrative electronic device of the type shown in  FIG. 8  may include multiple antennas for transmitting millimeter wave signals through a single antenna window in accordance with an embodiment. 
         FIG. 10  is a block diagram showing how a simplified baseband processor may provide data to radio-frequency circuitry that performs beam steering operations in accordance with an embodiment. 
         FIG. 11  is a diagram showing how an illustrative electronic device having a single antenna window for conveying millimeter wave signals may be insensitive to device orientation with respect to an external device in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may contain wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may be used for handling millimeter 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 10 GHz and 400 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 device  10  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 wrist-watch device, a pendant device, a headphone or earpiece 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, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, wearable device, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     Electronic device  10  may wirelessly communicate with external electronic devices such as external electronic device  12 . While in wireless communication with each other, devices  10  and  12  may sometimes be collectively referred to herein as wireless communications system  8 . Electronic device  12  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 wrist-watch device, a pendant device, a headphone or earpiece 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, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     Electronic device  10  may sometimes be referred to herein as first electronic device  10  or primary electronic device  10 , whereas electronic device  12  may sometimes be referred to herein as second electronic device  12 , secondary electronic device  12 , external electronic device  12 , or peripheral electronic device  12 . In one suitable arrangement, secondary device  12  may be an accessory or other peripheral device that supports the operations of primary device  10 . For example, secondary device  12  may be a docking device, synching device, charging device, or other accessory device for primary device  10 . The example of  FIG. 1  is merely illustrative and, if desired, other configurations may be used for device  12 . 
       FIG. 1  is a schematic diagram showing illustrative components that may be used in devices  10  and  12 . As shown in  FIG. 1 , first device  10  may include storage and processing circuitry such as storage and processing circuitry  16  and input-output (I/O) circuitry such as input-output circuitry  18 . Storage and processing circuitry  16  and input-output circuitry  18  may be enclosed within electronic device housing structures such as housing  14 . Housing  14 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  14  may be formed using a unibody configuration in which some or all of housing  14  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     Storage and processing circuitry  16  in first device  10  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 storage and processing circuitry  16  may be used to control the operation of first 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. 
     Storage and processing circuitry  16  may be used to run software on first device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, data transfer applications, etc. To support interactions with external equipment, storage and processing circuitry  16  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  30  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, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols, etc. 
     Input-output circuitry  18  on first device  10  may include input-output devices  26 . Input-output devices  26  may be used to allow data to be supplied to first device  10  and to allow data to be provided from first device  10  to external devices. Input-output devices  26  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, a connector port sensor or other sensor that determines whether first device  10  is mounted in a dock, and other sensors and input-output components. 
     Input-output circuitry  18  may include wireless communications circuitry  28  for communicating wirelessly with external equipment. Wireless communications circuitry  28  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 such as antennas  30 , 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  28  may include baseband processor circuitry  32  for handling transmitted and/or received signals at baseband frequencies. Baseband processor circuitry  32  may include any desired number of discrete baseband processors (e.g., one baseband processor, two baseband processors, more than two baseband processors, etc.). Baseband processor circuitry  32  may provide baseband signals to radio-frequency circuitry  34  over path  36  and/or may receive baseband signals from radio-frequency circuitry  34  over path  36 . 
     Radio-frequency circuitry  34  may up-convert the baseband signals to radio-frequency signals for transmission and may down-convert radio-frequency signals received over antennas  30  to generate baseband signals for baseband processor circuitry  32 . Baseband processor circuitry  32  may handle baseband versions of signals that are transmitted and/or received over any desired radio-frequency communications bands. 
     Radio-frequency circuitry  34  may include one or more radio-frequency (RF) module circuits  40  (e.g., a first RF module  40 - 1 , an Nth RF module  40 -N, etc.). Each radio-frequency module  40  may handle radio-frequency signals in a corresponding communications band. Each radio-frequency module  40  may include corresponding transceiver circuitry, filtering circuitry, transmission line structures, amplifier circuitry, data conversion circuitry, matching circuitry, control logic, or any other desired circuitry for handling radio-frequency signals in the corresponding frequency band. Each RF module  40  may be formed on a respective integrated circuit (chip). If desired, two or more of RF modules  40  may be formed on a common substrate or on a common integrated circuit chip. Two or more of modules  40  may be formed on a common substrate or integrated circuit with baseband processor  32 , or may be formed on separate substrates or integrated circuits than baseband processor  32 , for example. If desired, RF circuitry  34  and baseband circuitry  32  may be formed on separate integrated circuit chips or may both be formed on the same integrated circuit chip. If desired, radio-frequency circuitry  34  may include filtering circuitry, mixing circuitry, amplifier circuitry, transmission line structures, matching circuitry, data conversion circuitry (e.g., analog-to-digital converter circuitry or digital-to-analog converter circuitry), switching circuitry, and/or any other desired circuitry for handling radio-frequency signals that is separate from the circuitry formed on RF modules  40 . 
     Radio-frequency circuitry  34  may handle radio-frequency communications in various radio-frequency communications bands. Radio-frequency circuitry  34  may include wireless local area network transceiver circuitry that handles 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and that handles the 2.4 GHz Bluetooth® communications band. Circuitry  34  may include cellular telephone transceiver circuitry for handling wireless communications in frequency ranges such as a low communications band from 700 to 960 MHz, a midband from 1710 to 2170 MHz, and a high band from 2300 to 2700 MHz or other communications bands between 700 MHz and 2700 MHz or other suitable frequencies (as examples). Circuitry  34  may handle voice data and non-voice data. 
     Radio-frequency circuitry  34  may include millimeter wave transceiver circuitry that supports communications at extremely high frequencies (e.g., millimeter wave frequencies from 10 GHz to 400 GHz or other millimeter wave frequencies). Radio-frequency circuitry  34  may sometimes be referred to herein as millimeter wave circuitry  34 . Circuitry  34  may include satellite navigation system circuitry such as Global Positioning System (GPS) receiver circuitry 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 first device  10  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 and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. Extremely high frequency (EHF) wireless transceiver circuitry in circuitry  34  may convey signals over these short distances that travel between transmitter and receiver over a line-of-sight path. To enhance signal reception for millimeter wave communications, phased antenna arrays and beam steering techniques may be used if desired. 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 first device  10  can be switched out of use and higher-performing antennas used in their place. 
     Radio-frequency 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  30  in wireless communications circuitry  28  may be formed using any suitable antenna types. For example, antennas  30  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. If desired, one or more of antennas  30  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  30  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  30  can include one or more antennas or phased antenna arrays that handle millimeter wave communications if desired. 
     Transmission line paths may be used to route antenna signals within first device  10 . For example, transmission line paths may be used to couple antenna structures  30  to radio-frequency circuitry  34 . Transmission lines in first device  10  may include coaxial cable paths, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Filter circuitry, switching circuitry, amplifier circuitry, impedance matching circuitry, and other circuitry may be interposed within the transmission lines, if desired. 
     Similarly, second device  12  may include storage and processing circuitry  20  and input-output circuitry  22 . Storage and processing circuitry  20  and input-output circuitry  22  may be enclosed within electronic device housing structures such as housing  24 . Housing  24  may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  24  may be formed using a unibody configuration in which some or all of housing  24  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     Input-output circuitry  22  on second device  12  may include input-output devices  42 . Input-output devices  42  may be used to allow data to be supplied to second device  12  and to allow data to be provided from second device  12  to other devices. Input-output devices  42  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, a connector port sensor or other sensor that determines whether device  12  is mounted in a dock, and other sensors and input-output components. 
     Input-output circuitry  22  may include wireless communications circuitry  44 . Wireless communications circuitry  44  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 such as antennas  46 , 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  44  may include baseband processor circuitry  48  for handling transmitted and/or received signals at baseband frequencies. Baseband processor circuitry  48  may provide baseband signals to radio-frequency circuitry  50  over path  52  and/or may receive baseband signals from radio-frequency circuitry  50  over path  52 . Radio-frequency circuitry  50  may include radio-frequency modules  54  (e.g., a first module  54 - 1 , an Nth module  54 -N, etc.). Each radio-frequency module  54  may handle radio-frequency signals in a corresponding communications band. Each radio-frequency module  54  may include corresponding transceiver circuitry, filtering circuitry, transmission line structures, amplifier circuitry, data conversion circuitry, matching circuitry, control logic, or any other desired circuitry for handling radio-frequency signals in a corresponding frequency band. Each module  54  may be formed on a respective integrated circuit (chip). If desired, two or more of modules  54  may be formed on a common substrate or on a common integrated circuit chip. Two or more of modules  54  may be formed on a common substrate or integrated circuit with baseband processor  48  or may be formed on separate substrates or integrated circuits than baseband processor  48 , for example. 
     If desired, radio-frequency circuitry  50  may include filtering circuitry, mixing circuitry, amplifier circuitry, transmission line structures, matching circuitry, data conversion circuitry (e.g., analog-to-digital converter circuitry or digital-to-analog converter circuitry), switching circuitry, and/or any other desired circuitry for handling radio-frequency signals that is separate from the circuitry formed on modules  54 . 
     Radio-frequency circuitry  50  may handle radio-frequency communications in various radio-frequency communications bands. Radio-frequency circuitry  50  may include wireless local area network transceiver circuitry that handles 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and that handles the 2.4 GHz Bluetooth® communications band. Circuitry  50  may include cellular telephone transceiver circuitry for handling wireless communications in frequency ranges such as a low communications band from 700 to 960 MHz, a midband from 1710 to 2170 MHz, and a high band from 2300 to 2700 MHz or other communications bands between 700 MHz and 2700 MHz or other suitable frequencies (as examples). Circuitry  50  may handle voice data and non-voice data. 
     Radio-frequency circuitry  50  may include millimeter wave transceiver circuitry that supports communications at extremely high frequencies (e.g., millimeter wave frequencies from 10 GHz to 400 GHz or other millimeter wave frequencies). Circuitry  50  may include satellite navigation system circuitry such as Global Positioning System (GPS) receiver circuitry 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 device  12  are received from a constellation of satellites orbiting the earth. 
     Radio-frequency communications circuitry  50  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  50  may include circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. 
     Antennas  46  in wireless communications circuitry  44  may be formed using any suitable antenna types. For example, antennas  46  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. If desired, one or more of antennas  46  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  46  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  46  can include one or more antennas or phased antenna arrays for handling millimeter wave communications if desired. 
     Transmission line paths may be used to route antenna signals within device  12 . For example, transmission line paths may be used to couple antenna structures  46  to radio-frequency circuitry  50 . Transmission lines in device  12  may include coaxial cable paths, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within the transmission lines, if desired. 
     Storage and processing circuitry  16  on first device  10  and storage and processing circuitry  20  on second device  12  may be used in implementing data transfer protocols (sometimes referred to herein as data bus protocols). The data transfer protocols may be used to perform high data rate data transfer operations (e.g., data transfer operations at speeds of 100 Mega bits per second (Mbps) or more, at 500 Mbps or more, 1 bit per second or more, etc.). Data transfer protocols that may be implemented by processing circuitry  16  and  20  may include Universal Serial Bus (USB) protocols, universal asynchronous receiver/transmitter (UART) protocols, Peripheral Component Interconnect (PCI) protocols, Peripheral Component Interconnect Express (PCIe) protocols, Accelerated Graphics Port (AGP) protocols, or any other desired data transfer protocols capable of data speeds (i.e., data rates) of greater than or equal to approximately 100 Mbps. In general, the data transfer protocols may require at least two concurrent data paths to be maintained to support data transfer operations (e.g., a first path for transmitting data from a first device to a second device and a second path for concurrently transmitting data from the second device to the first device). 
     Processing circuitry  16  on first device  10  may format data for transmission using a selected data transfer protocol. In some scenarios, input-output devices  26  include wired data port structures such as USB ports that support high data rate transfer protocols. In these scenarios, data may be transmitted to an external device such as second device  12  over the wired data port and corresponding cabling structures. The wired data port and cabling structures may support data transmission at the high data rates associated with the data transfer protocol. However, cables and wired data ports required for implementing the data transfer protocol can be bulky and occupy excessive space within the device. If desired, space within the devices can be conserved by using wireless communications circuitry  28  to wirelessly transmitting data to external device  12 . 
     In general, the data transmission bandwidth and the data rate of wireless communications circuitry  28  (e.g., the number of data bits per second that can be transmitted by circuitry  28 ) are directly proportional to the frequency that is used to convey the data. For example, data transmitted in higher frequency bands may be conveyed at higher data rates than data conveyed at lower frequencies. While radio-frequency circuitry  34  may convey data at relatively low frequencies such as cellular telephone frequencies or wireless local area network frequencies, these frequencies impose an upper limit on the data rates that can be obtained when transmitting wireless data. For example, transferring data at these frequencies may limit data rates to less than 500 Mbps. Limiting the data rate in this manner can result in relatively long wait times for large data files such as high-definition video or other large sets of data to be transferred to an external device. 
     If desired, millimeter wave RF modules  40  in first device  10  may be used to transmit data at high data rates (e.g., rates of 500 Mbps or higher, 1 bit per second or higher, 5 Giga bits per second (Gbps), 5 Giga bytes per second (GBps), etc.) to external equipment. Data transfer operations using millimeter wave circuitry on device  10  can obtain significantly higher data rates than when lower frequencies such as wireless local area network or cellular telephone frequencies are used (e.g., because millimeter wave communications are performed at Extremely High Frequencies (EHF) of greater than 10 GHz, which is significantly greater than wireless local area network frequencies or cellular telephone frequencies). As such, device  10  may use EHF signals to transfer relatively large data files in a shorter or even unnoticeable amount of time relative to scenarios where lower frequencies are used. 
     In order to implement a data transfer protocol capable of handling data rates of 1 bit per second or higher, at least two EHF wireless paths may be established and concurrently maintained between first device  10  and second device  12 . As shown in  FIG. 1 , first and second devices  10  and  12  may establish a first wireless path  60  and a second wireless path  62  between the devices. First and second wireless paths  60  and  62  may be established using RF modules  40  on first device  10  and RF modules  54  on second device  12  that are capable of handling millimeter wave communications. First and second wireless paths  60  and  62  may sometimes be referred to herein as wireless links. First and second wireless links  60  and  62  may collectively form a wireless data transfer link between devices  10  and  12  that implements a corresponding data transfer protocol and that handles data transfer at rates of greater than or equal to 1 bit per second or rates at greater than or equal to 500 Mbps, for example. 
     In order to handle such high data rates, wireless links  60  and  62  may be at EHF frequencies of greater than or equal to 10 GHz. For example, EHF links  60  and  62  may established in frequency bands at 58.5 GHz, 60 GHz, 62.5 GHz, a frequency band between 58.5 and 60 GHz, a frequency band between 60 GHz and 62.5 GHz, a frequency band great than 62.5 GHz, a frequency band between 10 GHz and 58.5 GHz, etc. EHF links  60  and  62  may both convey signals over the same frequency band or may convey signals in different frequency bands. In implementing the corresponding data transfer protocol, wireless link  60  may be used to convey data in a direction from first device  10  to second device  12  whereas link  62  is used to convey data in a direction from second device  12  to first device  10 . If desired, more than two wireless links may be concurrently established between the devices. Data may be conveyed between first device  10  and second device  12  at relatively high data rates of 500 Mbps or more (e.g., 1 Gbps, 1 GBps, 5 Gbps, 10 Gbps, more than 10 Gbps, 5 GBps, more than 5 GBps, etc.). In some scenarios, data rates may be at rates of greater than or equal to 1 bit per second (e.g., between 1 bit per second and 100 Mbps, between 100 Mbps and 1 Gbps, etc.). 
     Different respective RF modules  40  in device  10  may be used to handle each of links  60  and  62 . For example, first RF module  40 - 1  may handle wireless transmission over link  60  whereas Nth RF module  40 -N handles wireless reception over link  62 . Similarly, different respective RF modules  54  in device  12  may be used to handle each of links  60  and  62 . For example, RF module  54 - 1  may handle wireless reception over link  60  whereas RF module  54 -N handles wireless transmission over link  62 . In this way, EHF signals transmitted by RF module  40 - 1  may be received by RF module  54 - 1  and EHF signals transmitted by module  54 -N may be received by RF module  40 -N. 
     If desired, the same frequency may be used for both EHF links  60  and  62 . In this scenario, RF module  40 - 1  may transmit signals for link  60  over a first antenna  30  and RF module  40 -N may receive signals from link  62  over a second antenna  30 . Similarly, RF module  54 - 1  may receive signals for link  60  over a first antenna  54 - 1  and RF module  54 -N may transmit signals for link  62  over a second antenna  46 . If desired, different frequencies may be used for links  60  and  62 . In this scenario, modules  40 - 1  and  40 -N may transmit and receive signals using the same antenna  30  (e.g., signals for links  60  and  62  may be handled using the same antenna  30 ). Similarly, RF module  54 - 1  and RF module  54 -N may transmit and receive signals using the same antenna  46 . 
       FIG. 2  is an illustrative diagram showing how antennas  30  may be formed within first device  10 . In the example of  FIG. 2 , device  10  includes a display such as display  70 . Display  70  may be mounted in housing  14 . Display  70  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. 
     Display  70  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. 
     Display  70  may be protected using a display cover layer such as a layer of transparent glass, clear plastic, sapphire, or other transparent dielectric. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  74 . An opening may also be formed in the display cover layer to accommodate ports such as a speaker port. Openings may be formed in housing  14  to form communications ports (e.g., an audio jack port, a digital data port, etc.). In scenarios where antennas  30  are used to convey data at high data rates over EHF bands to external devices, digital data ports such as USB ports and the corresponding openings in housing  14  may be omitted (e.g., thereby enhancing the form factor of device  10  and/or allowing for additional space within device  10  to be used in forming other components). 
     Antennas  30  may be mounted in housing  14 . For example, housing  14  may have four peripheral edges as shown in  FIG. 2  and one or more antennas may be located along one or more of these edges. As shown in the illustrative configuration of  FIG. 2 , antennas  30  may, if desired, be mounted in regions  76  and  78  along opposing peripheral edges of housing  12  (as an example). If desired, metal portions of housing  14  may form a portion of the antennas in device  10 . For example, external conductive surfaces of housing  14  may form portions of resonating elements and/or ground planes for antennas  40 . In one suitable arrangement, housing  14  includes a conductive rear surface and conductive sidewalls that extend from the rear surface to a dielectric cover of display  70 . Antennas  30  may also be mounted in other portions of device  10 , if desired. The configuration of  FIG. 2  is merely illustrative. 
     If desired, one or more of antennas  30  in device  10  may be used to convey both EHF data signals and radio-frequency signals at frequencies below EHF frequencies (e.g., wireless local area network signals, cellular telephone signals, NFC signals, satellite navigation signals, etc.). In another suitable arrangement, a first set of antennas  30  may be used to convey signals at EHF frequencies whereas a second set of antennas  30  are used to convey signals at frequencies below EHF frequencies. For example, antennas used to convey signals at frequencies below EHF frequencies may be formed in regions  78  and  76  and may have resonating elements formed from metal portions (e.g., external surfaces) of housing  14 . In other words, metal portions of housing  14  that surround a periphery of device  10  may form non-EHF antennas for device  10 . In this example, one or more separate antennas may be used to convey EHF signals. The antennas that convey EHF signals may be mounted adjacent to the rear metal surface of housing  14 . The rear metal surface of housing  14  may include one or more dielectric antenna windows. The antennas that convey EHF signals may convey wireless EHF signals through the dielectric antenna windows (e.g., so that the metal housing does not block the signals). This example is merely illustrative. The arrangement shown in  FIG. 2  may also be used for implementing second electronic device  12  if desired. 
       FIG. 3  is an illustrative diagram that may be used for handling EHF signals over links  60  and/or  62 . The radio-frequency module of  FIG. 3  may, for example, be used to implement one of radio-frequency modules  40  of first device  10  or one of radio-frequency modules  54  of second device  12  of  FIG. 1 . RF module  80  (e.g., an RF module such as module  40 - 1  or  40 -N of device  10  or module  54 - 1  or  54 -N of device  12 ) may handle communications in an EHF band. The components of module  80  may be formed on a common substrate or on a common integrated circuit, if desired. 
     As shown in the example of  FIG. 3 , baseband circuitry  32  may be formed as a portion of RF module  80  (e.g., baseband circuitry  75  may include some or all of baseband circuitry  32  of  FIG. 1 ). In another suitable arrangement, baseband circuitry  32  may be formed separately from module  80 . Module  80  may include input-output (I/O) circuitry  77  coupled to an input of baseband circuitry  75  and radio-frequency circuitry  71  coupled to an output of baseband circuitry  75 . I/O circuitry  77  may serve as an input-output interface with data path  81 . I/O circuitry  77  may receive data for transmission (e.g., from processing circuitry  16 ) over data path  81 . 
     Baseband circuitry  75  may receive the data via I/O circuitry  77  and may perform baseband operations on the received data. Radio-frequency circuitry  71  may perform radio-frequency up-conversion on the data to convert the baseband signals to EHF signals. Radio-frequency circuitry  71  may be coupled to output path  90 . Output path  90  may be a transmission line path to antennas  30  or to other antennas in the device. The EHF signals may be conveyed to output path  90 . Similarly, EHF signals may be received over path  90 . The EHF signals may be down-converted to baseband signals by circuitry  71 . Baseband circuitry  75  may perform baseband operations on the received baseband signals and may convey the baseband signals to path  81  over I/O path  77 . Radio-frequency circuitry  71  may include any desired filtering circuitry, switching circuitry, matching circuitry, conversion circuitry, mixing circuitry, or amplifying circuitry. 
     RF module  80  may include control and debug circuitry  79 . Circuitry  79  may provide control signals to circuitry  77 ,  75 , and  71  via intra-module control paths (not shown). Circuitry  79  may receive control signals from other circuitry via inter-chip control path  110 . Circuitry  79  may provide control signals to other circuitry such as other radio-frequency modules via control path  110 . Circuitry  79  may control the operation of module  80 , may control the operation of other radio-frequency modules on device  10  and/or device  12 , and may perform testing and link quality evaluation operations on EHF links  60  and  62 . 
     Module  80  of  FIG. 3  may include amplifier circuitry such as a transmit (power) amplifier and a low noise amplifier (LNA). The amplifier circuitry may be formed in radio-frequency portion  71 , may be interposed on transmission line  90 , may be formed external to module  80  and interposed on transmission line  90 , etc. When conveying data for transmission, the power amplifier circuitry may receive signals for transmission over input path  81 . The amplifier may amplify (e.g., provide a greater-than-unity gain) to the received transmit signals and may provide the amplified signals to transmission line  90 . Output path  90  may convey the transmit signals to antennas  30  via other filtering circuitry, amplifier circuitry, and/or transmission line structures in radio-frequency circuitry  34  ( FIG. 1 ). The gain provided by the amplifiers may be adjusted using amplifier control signals. The amplifier control signals may include gain adjustment control signals, signals for adjusting amplifier bias, signals for activating a desired number of amplifier gain stages, or any other desired control signals for adjusting the gain provided by the amplifiers. The control signals may be provided by control circuitry  79 , by storage and processing circuitry  16  ( FIG. 1 ), or by other power control circuitry on first device  10 . The amplifiers may be adjusted using control signals to provide transmit signals on output path  90  at a desired transmit power level. The amplifiers may be adjusted using control signals to increase or decrease the transmit power level of EHF signals at output path  90  in real time. 
     If desired, radio-frequency circuitry  71  may receive radio-frequency signals from path  90 . The received signals may be passed to the input of a low noise amplifier. The low noise amplifier may amplify the received signals and may output the amplified signals to circuitry  75 . Control circuitry  79  may sometimes be referred to herein as control logic. Control circuitry  79  may be configured using control signals received over control path  110  (e.g., control signals received from storage and processing circuitry  16  on the device via path  110 ). Control circuitry  79  may provide control signals to other radio-frequency modules  40  over path  110  to control the operation of those radio-frequency modules. Paths  81 ,  90 , and/or  110  may include radio-frequency transmission line structures and/or conductive contacts such as conductive pins, contact pads, or vias, if desired. Control path  110  may convey data organized according to an Inter-Chip Communication (ICC) protocol, for example. 
     If desired, control circuitry  79  may include debugging circuitry. The debugging circuitry may be used to perform debugging or test operations on device  10 , device  12 , and/or EHF wireless links  60  and  62 . For example, the debugging circuitry may generate a sequence of test bits such as a pseudo-random bit sequence (e.g., a series of pseudo-random data bits). Circuitry  79  may inject the test bits onto path  90  via radio-frequency circuitry  71 . The test bits may be transmitted over path  90  and received at external device  12  (in scenarios where module  80  is formed on first device  10 ). External device  12  may process the received test bits to test the quality of wireless links  60  and  62  if desired. 
     If care is not taken, data transmitted over EHF wireless link  60  may interfere with data transmitted over EHF wireless link  62  and/or data over link  62  may interfere with data transmitted over link  60 . In scenarios where links  60  and  62  are at the same EHF frequency band (e.g., when different respective antennas  30  are used to convey signals for each link), radio-frequency shielding structures such as shield  120  may be formed around one or more sides of module  80  to mitigate interference between the data links. Shield  120  may include a conductive structure such as a metal sheet or other structure for blocking radio-frequency signals. Shield  120  may be interposed between RF modules  40 - 1  and  40 -N. If desired, shield  120  may extend around one, two, or three sides of module  80 . If desired, radio-frequency absorber structures such as absorber  122  may be formed around one or more sides of module  80 . Absorber  122  may include dielectrics or other materials for absorbing radio-frequency signals. Absorber  122  may be interposed between RF modules  40 - 1  and  40 -N. If desired, absorber  122  may extend around, one, two, three, or four sides of module  80 . Module  80  may be provided with absorber  122 , shield  120 , shield  120  and absorber  122 , or shield  120  and absorber  122  may be omitted. Shield  120  and absorber  122  may serve to reduce interference between modules  40 - 1  and  40 -N. This may allow modules  40 - 1  and  40 -N to be placed closer together on device  10  than in scenarios where no shields or absorbers are used. 
     Radio-frequency circuitry  34  on first device  10  and radio-frequency circuitry  50  on second device  12  may transmit EHF signals at desired transmit power levels. The transmit power levels may be determined by the gain provided by amplifiers within and/or external to modules  80  on each device. In general, higher transmit power levels may result in a higher wireless link quality than lower transmit power levels. However, higher transmit power levels may use more power and deplete batteries on the devices faster than when lower transmit power levels are used. 
     If desired, device  10  and/or device  12  may actively perform transmit power level adjustments for links  60  and  62  in real time. By adjusting the transmit powers in real time (e.g., while links  60  and  62  are already established), system  8  may ensure that the EHF wireless links have sufficient link quality while optimizing power consumption within the devices. 
       FIG. 4  is a flow chart of illustrative steps that may be performed by communications system  8  for adjusting the transmit powers of EHF links  60  and  62  in real time. 
     At step  130 , devices  10  and  12  may establish EHF wireless data transfer links  60  and  62  between devices  10  and  12  ( FIG. 1 ). For example, RF module  40 - 1  on device  10  may establish wireless link  60  with RF module  54 - 1  on device  12  in an EHF frequency band whereas RF module  40 -N on device  10  establishes wireless link  62  with RF module  54 -N on device  12  in an EHF frequency band. Once the links have been established, RF module  40 - 1  may transmit data over link  60  to RF module  54 - 1  and RF module  54 -N may transmit data over link  62  to RF module  40 -N. Established links  60  and  62  may collectively implement a high speed data transfer protocol such as PCIe, USB, modified versions of these, or any other desired data transfer protocol. RF module  54 -N may transmit data over link  62  at a first predetermined transmit power level and module  40 - 1  may transmit data over link  60  at a second predetermined transmit power level. 
     Devices  10  and  12  may establish links  60  and  62  using a wireless handshake procedure if desired. For example, RF module  54 -N on second device  12  may generate a predetermined series of data bits such as a device token and may transmit the device token to RF module  40 -N on first device  10  (e.g., over an EHF frequency band). Control circuitry (e.g., circuitry  79  of  FIG. 3 ) on RF module  40 -N may obtain the received device token and may identify that second device  12  is attempting to establish an EHF wireless link with first device  10 . Control circuitry  79  on RF module  40 -N may provide control signals to RF module  40 - 1  over control path  110  on first device  10 . The control signals may instruct RF module  40 - 1  to generate a response message. RF module  40 - 1  may transmit the response message to RF module  54 - 1  (e.g., over an EHF frequency band). RF module  54 - 1  may identify the received response message and may identify that first device  10  is ready for communication. RF module  54 - 1  may send control signals to RF module  54 -N over control path  110  on second device  12  to inform RF module  54 -N that a response has been received from first device  10 . Once RF module  54 -N has identified that the response has been received, links  60  and  62  may be successfully established and data may be conveyed over links  60  and  62  normally (e.g., at a high data rate of greater than 500 Mbps, at a data rate of greater than 1 bit per second, etc.). 
     At step  132 , first device  10  and/or second device  12  may evaluate the quality of established EHF links  60  and  62 . For example, RF module  40 -N may receive data from RF module  54 -N over EHF link  62 . Module  40 -N may pass the received data to baseband processor circuitry  32  (or baseband circuitry  75  in the example of  FIG. 3 ). Data processing circuitry in baseband  32  and/or in storage and processing circuitry  16  on first device  10  may process the received data to evaluate/analyze the quality of EHF link  62 . Similarly, RF module  54 - 1  may receive data from RF module  40 - 1  over EHF link  60 . Module  54 - 1  may pass the received data to baseband processor circuitry  48 . Data processing circuitry in baseband  48  and/or in storage and processing circuitry  20  on second device  12  may process the received data to evaluate/analyze the quality of EHF link  62 . 
     The quality of EHF link  62  may be evaluated using any desired wireless performance metrics. First device  10  and/or second  12  may gather wireless performance metric data from the received data and may use the performance metric data to characterize the quality of EHF links  60  and  62 . Performance metric data gathered by first device  10  and/or second device  12  for evaluating EHF wireless link quality may include, for example, received power, receiver sensitivity, frame error rate, bit error rate, channel quality measurements based on received signal strength indicator (RSSI) information, adjacent channel leakage ratio (ACLR) information (e.g., ACLR information in one or more downlink frequency channels), channel quality measurements based on received signal code power (RSCP) information, channel quality measurements based on reference symbol received power (RSRP) information, channel quality measurements based on signal-to-interference ratio (SINR) and signal-to-noise ratio (SNR) information, metrics measuring interference between links  60  and  62 , channel quality measurements based on signal quality data such as Ec/Io or Ec/No data, any desired combination of these performance metrics, and other information that is reflective of the quality of EHF links  60  and  62 . 
     First device  10  and/or second device  12  may process the generated performance metric data to determine whether the quality of EHF links  60  and/or  62  is satisfactory. For example, first device  10  and/or second device  12  may compare the generated performance metric data to corresponding performance metric threshold values or ranges of acceptable values. If the generated performance metric values are within a corresponding range of acceptable values, are below a threshold defining an upper limit of acceptable values, or are above a threshold defining a lower limit of acceptable values, devices  10  and  12  may identify that the EHF links have satisfactory link quality. The range of acceptable values and corresponding threshold values may be determined by an operator of system  8 , a wireless carrier, industry standards or regulations, a manufacture of device  10  and/or  12 , or by any other desired means. If first and second devices  10  and  12  identify that EHF links  60  and  62  have satisfactory link quality, devices  10  and  12  may continue to transmit data at the same transmit power levels. As shown by path  134 , devices  10  and  12  may continue to evaluate the quality of established EHF links  60  and  62  in real time. 
     If first device  10  and/or second device  12  determine that one or both of EHF links  60  and  62  have unsatisfactory link quality, processing may proceed to step  138  as shown by path  136 . At step  138 , the transmit power levels of first device  10  and/or second device  12  may be adjusted (e.g., increased or decreased). Transmit power level adjustments may be performed between RF modules on each device (e.g., between modules  40 - 1  and  40 -N on device  10  or between modules  54 - 1  and  54 -N on device  12 ) by conveying control signals over inter-chip control paths  110 . If desired, transmit power level adjustments may be performed by conveying control signals between devices  10  and  12  over EHF links  60  and  62 . 
     For example, RF module  54 - 1  on second device  12  may determine that EHF link  60  has unsatisfactory link quality (e.g., processing circuitry  20  on second device  12  may determine that performance metric data gathered for data received over link  60  lies outside of a range of acceptable performance metric data values). Module  54 - 1  and/or storage and processing circuitry  20  may identify that RF module  40 - 1  needs to adjust the transmit power level of EHF link  60 . Module  54 - 1  may transmit control signals to RF module  54 -N over inter-chip control path  110  on second device  12 . The control signals may identify the transmit power level change for RF module  40 - 1 . RF module  54 -N may transmit the received control signals to RF module  40 -N over wireless EHF path  62 . RF module  40 -N may receive the control signals from RF module  54 -N and may convey the control signals to RF module  40 - 1  over the inter-chip control path  110  on first device  10 . RF module  40 - 1  may adjust the transmit power level provided to signals transmitted over EHF link  60  based on the received control signals. 
     As another example, RF module  40 -N on first device  10  may determine that EHF link  62  has unsatisfactory link quality (e.g., processing circuitry  16  on device  10  may determine that performance metric data gathered for data received over link  62  lies outside of a range of acceptable performance metric data values). Module  40 -N and/or storage and processing circuitry  16  may identify that RF module  54 -N on second device  12  needs to adjust the transmit power level of EHF link  62 . Module  40 -N may transmit control signals to RF module  40 - 1  over the inter-chip control path  110  on first device  10 . The control signal may identify the transmit power level change for RF module  54 -N. RF module  40 - 1  may transmit the received control signal to RF module  54 - 1  over EHF path  60 . RF module  54 - 1  may receive the control signal from RF module  40 - 1  and may convey the control signal to RF module  54 -N over the inter-chip control path  110  on second device  12 . RF module  54 -N may adjust the transmit power level provided to signals transmitted over EHF link  62  based on the received control signals. 
     The adjustments to transmit power levels for EHF link  60  and  62  may ensure that links  60  and  62  have a satisfactory link quality. If desired, the adjustments to transmit power levels may ensure that the transmitted signals are provided with a desired amount of jitter. First device  10  and second device  12  may continue to transmit data normally using the adjusted transmit power levels. Processing may subsequently loop back to step  132  as shown by path  140  to continue to evaluate the quality of EHF links  60  and  62  in real time (e.g., to ensure that the transmit power levels are updated if link quality deviates over time). In this way, devices  10  and  12  may perform loop feedback power adjustments (e.g., adjustments to the EHF links based on active feedback obtained from measurements of the EHF links) for EHF links  60  and  62  to ensure that the quality of links  60  and  62  are optimized over time. 
     If desired, debugging circuitry  79  on RF module  80  may generate test data for evaluating the quality of EHF links  60  and  62 .  FIG. 5  is a flow chart of illustrative steps that may be performed by first and second devices  10  and  12  for evaluating the quality of EHF links  60  and  62  using generated test data. The steps of  FIG. 5  may, for example, be performed while processing step  132  of  FIG. 4 . 
     At step  150 , one of devices  10  and  12  may generate a test bit sequence using corresponding debugging circuitry  79 . For example, debugging circuitry  79  on RF module  40 - 1  of first device  10  may generate a test bit sequence. The test bit sequence may be a stream of data bits. Debugging circuitry  79  may include pseudo-random number generator circuitry that generates the test bit sequence as a pseudo-random sequence of data bits (e.g., a pseudo-random sequence of binary “1” and “0”). The pseudo-random sequence of data bits may sometimes be referred to herein as a pseudo-random bit sequence (PRBS). 
     At step  152 , control circuitry  79  may inject the generated test bit sequence onto the corresponding transmit path. For example, circuitry  79  on RF module  40 - 1  may inject the generated test bit sequence onto transmit path  90  via circuitry  71 . RF-module  40 - 1  may transmit the test bit sequence over EHF link  60  to second device  12 . 
     At step  154 , RF module  54 - 1  on second device  12  may receive the transmitted test bit sequence over EHF link  60 . For example, module  54 - 1  may extract the test bit sequence from other data that is received over link  60 . Module  54 - 1  may pass the received test bit sequence to baseband processor  48  for processing. 
     At step  156 , baseband processor  48  and/or storage and processing circuitry  20  may process the received test bit sequence to identify the quality of EHF link  60 . For example, circuitry  20  may compare the test bit sequence received from RF module  54 - 1  to a predetermined sequence to identify a bit error rate or other performance metric information associated with EHF link  60 . Bit error rate values identified by circuitry  20  may, for example, be a measure of the number of incorrectly received bits in the received test bit sequence (e.g., higher bit error rate values may be indicative of a poorer link quality whereas lower bit error rate values may be indicative of a higher link quality). This example is merely illustrative and, in general, any desired wireless performance metrics may be used. A similar procedure may be performed at first device  10  for processing test bit sequences received from second device  12 . By injecting test data bits using RF modules  40  and  54 , modules  40  and  54  and the corresponding EHF links  60  and  62  may be characterized without expensive external testing equipment. 
     Antennas  30  for conveying EHF signals over links  60  and  62  may be formed within a housing  14  having metal housing portions. The metal housing portions may provide an attractive form factor to device  10  and/or may form a portion of one or more antennas within the device. In general, conductors such as metal portions of housing  14  may block radio-frequency signals. Openings may be formed in metal portions of housing  14  to allow for EHF wireless signals to be conveyed to and from antennas  30 . If desired, the openings may be filled with dielectric material to form dielectric antenna windows in the metal housing. The dielectric antenna windows may allow EHF signals to be conveyed into or out of the metal housing while blocking dirt, moisture, or other debris from entering the interior of the housing. 
       FIG. 6  shows a rear view of first device  10  having metal housing portions  14  and at least two dielectric antenna windows formed in metal housing portions  14 . As shown in  FIG. 6 , rear surface  162  of first device  10  may be formed from metal housing portions  14  (e.g., a planar metal layer or sheet extending across the width and length of the device). Rear surface  162  may be formed on an opposite side of device  10  from display  70  ( FIG. 2 ). At least two dielectric antenna windows  160  may be formed in openings in metal housing  14 . Dielectric antenna windows  160  may be formed from any desired dielectric materials (e.g., polymer, plastic, glass, ceramic, sapphire, rubber, combinations of these materials, etc.). 
     Each antenna window  160  may be formed over a corresponding antenna  30 . For example, a first antenna window  160  may be formed over a given antenna  30  that is used to convey signals associated with EHF link  60  whereas a second antenna window  160  may be formed over a given antenna  30  that is used to convey signals associated with EHF link  62 . In other words, RF module  40 - 1  and RF module  40 -N may transmit or receive signals through two different antenna windows  160  in housing  14 . The use of two different antenna windows for each link may allow for the windows and thus the corresponding RF modules to be formed relatively far apart in device  10 . Such spatial separation may allow for an increase in spatial isolation between links  60  and  62 , and a corresponding reduction in interference between the links. 
     The example of  FIG. 6  is merely illustrative. In general, windows  160  may have any desired shape (e.g., a circular shape, oval shape, rectangular shape, polygonal shape, a logo shape, etc.). Each of windows  160  may be the same size or may be different sizes. Each of windows  160  may be the same shape or may be different shapes. In the example of  FIG. 6 , windows  160  are formed adjacent to the bottom of device  10 . In general, windows  160  may be formed at any desired location on surface  162 . Similar windows  160  may be formed on second device  12  when device  12  includes metal housing portions, if desired. 
     If desired, RF modules  40 - 1  and  40 -N may transmit and receive EHF signals through the same antenna window in metal housing  14 .  FIG. 7  shows a rear view of device  10  in an example where EHF links  60  and  62  are conveyed through a single antenna window. As shown in  FIG. 7 , a single antenna window  164  may be formed in rear surface  162  of metal housing  14 . Antenna window  164  may be formed from any desired dielectric materials. Each antenna  30  that is used to convey EHF signals for RF module  40 - 1  and RF module  40 -N may transmit and/or receive signals associated with EHF links  60  and  62  through window  164 . For example, a first antenna  30  that transmits signals from RF module  40 - 1  may transmit the signals through window  164  and a second antenna  30  that receives signals associated from RF module  54 -N may receive the signals through antenna window  164 . 
     The example of  FIG. 7  is merely illustrative. In general, window  164  may have any desired shape (e.g., a circular shape, oval shape, rectangular shape, polygonal shape, a logo shape, etc.). Window  164  may have any desired size (e.g., window  160  may extend across the entire width of device  10  or a fraction of the width of rear surface  162 ). Window  164  may be formed adjacent to the bottom side of device  10  or at any other desired location on rear surface  162  (e.g., in the center of surface  162 , adjacent to the top side of device  10 , etc.). A similar window  164  may be formed on second device  12  when device  12  includes metal housing portions, if desired. 
     In practice, conveying EHF signals for both modules  40 - 1  and  40 -N over separate antennas  30  and through the same antenna window  164  may introduce excessive interference between EHF links  60  and  62  (e.g., due to the relatively short spatial separation between the RF modules when a single antenna window is used). If desired, modules  40 - 1  and  40 -N may transmit and receive signals for EHF links  60  and  62  over the same antenna  30 . In this scenario, only a single antenna  30  for communicating over links  60  and  62  is formed behind window  164 . 
     In order to compensate for the lack of spatial separation between the RF modules in this scenario, devices  10  and  12  may, if desired, perform time division duplexing operations for concurrently maintaining EHF links  60  and  62 . In a time division duplexing scheme, EHF signals for link  60  may be interspersed in time with EHF signals for link  62  using switching circuitry on first device  10  and second device  12 . For example, signals for EHF link  60  may be conveyed during a first set of time periods and signals for EHF link  62  may be conveyed during a second set of time periods that is interspersed with the first set of time periods. Performing time division duplexing may help to mitigate interference between EHF links  60  and  62  (e.g., because only one of EHF links  60  and  62  is being used for data transmission at a given time). However, performing time division duplexing may undesirably limit the data rate of the EHF link to 500 MBps or less. 
     If desired, devices  10  and  12  may perform frequency division duplexing operations for maintaining EHF links  60  and  62  when a single antenna  30  is used. In a frequency division duplexing scheme, EHF signals for link  60  are transmitted by first device  10  in a first frequency band and EHF signals for link  62  are transmitted by second device  12  in a second frequency band that is different from the first frequency band. Filtering circuitry in radio-frequency circuitry  34  on first device  10  and in radio-frequency circuitry  50  on second device  12  may allow for simultaneous transmission and reception of signals for EHF links  60  and  62  over a single antenna and through a single antenna window  164 . 
       FIG. 8  is an illustrative diagram showing how devices  10  and  12  may perform frequency division duplexing operations. The frequency division duplexing operations may allow for simultaneous reception and transmission of EHF signals over a single antenna and through a single corresponding antenna window in each device. 
     As shown in  FIG. 8 , first device  10  may include metal housing  14  having dielectric antenna window  164 . A single antenna  30  for handling EHF communications may be formed within housing  14  adjacent to dielectric antenna window  164 . Second device  12  may include metal housing  24  having dielectric antenna window  178 . A single antenna  46  for handling EHF communications may be formed within metal housing  24  and adjacent to dielectric antenna window  178 . 
     RF module  40 - 1  on first device  10  may receive signals in a first EHF band over path  172 . RF module  40 - 1  may transmit the signals in the first EHF band over transmission line path  200 , duplexer structures  170 , transmission line path  208 , and a single antenna  30 . In this way, RF module  40 - 1  may serve as a millimeter wave transmitter (TX) for first device  10 . The signals transmitted by module  40 - 1  may be conveyed from antenna  30  to antenna  46  on second device  12  over EHF link  60 . 
     RF module  54 - 1  on second device  12  may receive the transmitted signals associated with EHF link  60  (e.g., the signals in the first EHF band) via a single antenna  46 , transmission line structures  210 , duplexer structures  176 , and transmission line structures  206 . RF module  54 - 1  may convey the received signals over path  180 . In this way, RF module  54 - 1  may serve as a millimeter wave receiver (RX) for second device  12 . 
     RF module  54 -N on second device  12  may receive signals in a second EHF band over path  182 . RF module  54 -N may transmit the signals in the second EHF band over transmission line path  204 , duplexer structures  176 , transmission line path  210 , and antenna  46 . In this way, RF module  54 -N may serve as a millimeter wave transmitter (TX) for second device  12 . The signals transmitted by module  54 -N may be conveyed from antenna  46  to antenna  30  on first device  10  over EHF link  62 . 
     RF module  40 -N on first device  10  may receive the transmitted signals associated with EHF link  62  (e.g., the signals in the second EHF band) via antenna  30 , transmission line structures  208 , duplexer structures  170 , and transmission line structures  202 . RF module  40 -N may convey the received signals over path  174 . In this way, RF module  40 -N may serve as a millimeter wave receiver (RX) for first device  10 . The first frequency band handled by modules  40 - 1  and  54 - 1  may be, for example, a 60 GHz frequency band, a 62.5 GHz frequency band, a 58.5 GHz frequency band, a frequency band at a frequency between 60 and 62.5 GHz, a frequency band at a frequency between  10  and 58.5 GHz, a frequency band at a frequency between 58.5 and 60 GHz, or a frequency band at a frequency greater than 62.5 GHz. The second frequency band handled by modules  40 -N and  54 -N may be, for example, a 60 GHz frequency band, a 62.5 GHz frequency band, a 58.5 GHz frequency band, a frequency band at a frequency between 60 and 62.5 GHz, a frequency band at a frequency between 10 and 58.5 GHz, a frequency band at a frequency between 58.5 and 60 GHz, or a frequency band at a frequency greater than 62.5 GHz (e.g., as long as the first and second frequency bands are different so as to allow for frequency division duplexing). In one particular example, RF module  40 - 1  and RF module  54 - 1  handle EHF signals in a 62.5 GHz frequency band whereas RF module  40 -N and RF module  54 -N handle EHF signals in a 58.5 GHz frequency band. In another example, RF modules  40 - 1  and  54 - 1  handle EHF signals in a 58.5 GHz frequency band whereas RF modules  40 -N and  54 -N handle EHG signals in a 62.5 GHz frequency band. 
     Radio-frequency circuitry  34  on first device  10  may include filtering circuitry such as duplexer circuitry  170 . Capacitor-based and inductor-based filtering components have little to no effect on signals on millimeter waves having a frequency of 10 GHz or higher. Duplexer  170  may thereby perform millimeter wave signal filtering operations without using capacitor or inductor components. Duplexer  170  may include EHF duplexer structures that are capable of handling and filtering signals at frequencies of greater than 10 GHz. For example, duplexer  170  may include resonant cavities and waveguide structures that are coupled together to form the desired filtering structures. The resonant cavity and waveguide structures may have sizes and shapes that are configured to handle and filter signals at frequencies greater than 10 GHz. 
     Duplexer  170  may have a first port coupled to RF module  40 - 1  via transmission line path  200 , a second port coupled to RF module  40 -N via transmission line path  202 , and third port coupled to antenna  30  via transmission line path  208 . If desired, amplifier circuits may be interposed on transmission line structures  200  and/or  202 . The cavity and waveguide filter structures in duplexer  170  may provide high isolation between paths  200  and  202 . For example, the cavities and waveguides in duplexer  170  may have a desired shape and arrangement so as to isolate 58.5 GHz signals from 62.5 GHz signals (e.g., in scenarios where links  60  and  62  are 62.5 GHz and 58.5 GHz links, respectively). Duplexer  170  may help prevent the relatively high magnitude EHF signals transmitted by RF module  40 - 1  from being received by RF module  40 -N, thereby providing high EHF isolation between the RF modules. In this way, duplexer  170  may allow for EHF signals in the first and second EHF frequency bands to be simultaneously transmitted and received over a single antenna  30  without generating interference from the signals transmitted by RF module  40 - 1  onto RF module  40 -N. 
     Radio-frequency circuitry  50  on second device  12  may include filtering circuitry such as duplexer circuitry  176 . Duplexer  176  may be millimeter wave duplexer circuitry that is capable of handling signals at frequencies of greater than 10 GHz. Duplexer  176  may include resonant cavities and waveguide structures that are coupled together to form the desired filtering structures. The resonant cavity and waveguide structures may sizes and shapes that are configured to handle and filter signals at frequencies greater than 10 GHz. 
     Duplexer  176  may have a first port coupled to RF module  54 -N via transmission line path  204 , a second port coupled to RF module  54 - 1  via transmission line path  206 , and third port coupled to antenna  46  via transmission line path  210 . If desired, amplifier circuits may be interposed on transmission line paths  206  and/or  204 . The cavity and waveguide filter structures in duplexer  176  may provide high isolation between paths  206  and  204 . For example, the cavities and waveguides in duplexer  170  may have a desired shape and arrangement so as to isolate 58.5 GHz signals from 62.5 GHz signals (e.g., in scenarios where links  60  and  62  are 62.5 GHz and 58.5 GHz links, respectively). Duplexer  176  may help prevent the relatively high magnitude EHF signals transmitted by RF module  54 -N from being received by RF module  54 - 1 , thereby providing high EHF isolation between the RF modules. In this way, duplexer  176  may allow for EHF signals to be simultaneously transmitted and received over antenna  46  without generating interference from the signals transmitted by RF module  54 -N onto RF module  54 - 1 . As shown in  FIG. 8 , high data rate EHF data links  60  and  62  are both conveyed through a single antenna window  164  in metal housing  14 . Use of a single antenna window for conveying both links  60  and  62  may allow for an improved aesthetics and reduced manufacturing complexity relative to scenarios where two antenna windows  160  are formed. A single antenna window may also reduce the rotational sensitivity of device  10  relative to scenarios where two or more antenna windows are used. 
     The example of  FIG. 8  is merely illustrative. If desired, duplexers  170  and  178  may be replaced with diplexer circuitry or any other desired circuitry for isolating multiple signals at frequencies of greater than 10 GHz. In the example of  FIG. 8 , a single antenna is used to convey EHF signals for each device. If desired, two or more antennas may be used in each device for conveying EHF signals. 
       FIG. 9  is an illustrative diagram showing how device  10  may include multiple antennas for conveying EHF signals. As shown in  FIG. 9 , duplexer circuitry  170  may be coupled to multiple antennas  214  through switching circuitry  211 . Antennas  214  may include two or more antennas such as antenna  30  of the type described above in connection with  FIGS. 1-8 . Antennas  214  may include, for example, two antennas, three antennas, four antennas, or more than four antennas. In one suitable arrangement, antennas  214  may be a phased antenna array. Each of antennas  214  may transmit and/or receive EHF signals through a single antenna window  164  in metal housing  14  if desired. 
     Each of the antennas  214  may be used together or one or more of the antennas may be switched into use while other antenna(s) are switched out of use. If desired, control circuitry such as storage and processing circuitry  16  ( FIG. 2 ) may be used to select an optimum antenna to use for EHF communications in real time and/or to select an optimum setting for adjustable wireless circuitry associated with one or more antennas  214 . Antenna adjustments may be made to tune antennas to perform in desired frequency ranges, to perform beam steering (e.g., in scenarios where antennas  214  include a phased antenna array), and to otherwise optimize antenna performance. For example, control circuitry  16  may control switch  211  by providing control signals  212  to switch  211 . Control circuitry  16  may use control signals  212  to switch one or more antennas  214  into use (e.g., by coupling the antennas to duplexer  170  over transmission line  208 ) while switching other antennas  214  out of use (e.g., by de-coupling the antennas from transmission line  208 ). 
     In some configurations, antennas  214  may include antenna arrays (e.g., phased antenna arrays to implement beam steering functions). For example, the antennas that are used in handling millimeter wave signals for extremely high frequency wireless transceiver modules  40  may be implemented as phased antenna arrays. The radiating elements in a phased antenna array for supporting millimeter wave communications may be patch antennas, dipole antennas, or other suitable antenna elements. Antennas  214  may be integrated with RF modules  40  to form integrated phased antenna array and transceiver circuit modules if desired. If desired, control circuitry  16  may adjust switch  211  to perform beam steering over an array of antennas  214 . In this scenario, radio-frequency circuitry  34  may include phase adjustment circuitry (not shown) for adjusting the relative phases of signals provided to each of the antennas  214  (e.g., so that the transmitted signals have peaks and troughs such that the transmitted signals are effectively steered in a desired direction). While the example of  FIG. 9  is described in connection with first device  10  of communications system  8 , second device  12  may include similar structures for allowing multiple antennas to convey EHF signals through a single antenna window  178 . 
     If desired, RF modules  40 - 1 ,  40 -N,  54 - 1 , and  54 -N as shown in  FIGS. 8 and 9  may perform active feedback transmit power level adjustments as described above in connection with  FIG. 3 . For example, RF module  110  may actively determine that established EHF link  62  has an unacceptable link quality. RF module  40 -N may convey control signals to RF module  40 - 1  over control path  110  identifying changes to be made to the transmit power level of link  62 . In another suitable arrangement processing circuitry  16  ( FIG. 1 ) may convey control signals to RF module  40 - 1  identifying changes to be made to the transmit power level of link  62 . RF module  40 - 1  may transmit the control signals over transmission path  200 , duplexer  170 , transmission path  208 , and antenna  30  so that the control signals are conveyed through antenna window  164  and to antenna  46  on second device  12  (e.g., over EHF link  60 ). 
     The control signals may be routed over transmission line  210 , duplexer  176 , and transmission line  206  to RF module  54 - 1 . Control circuitry  79  in RF module  54 - 1  may identify the received control signals and may route the control signals to RF module  54 -N over path  110 . RF module  54 -N may perform transmit power level adjustments based on the received control signals. The transmit power level adjustments may affect the link quality of EHF link  62 . First device  10  may continue to evaluate the quality of link  62 . If first device  10  determines that the adjusted transmit power has resulted in sufficient link quality for EHF link  62 , data may continue to be transmitted normally. If first device  10  determines that the adjusted transmit power level has still resulted in insufficient link quality for EHF link  62 , first device  10  may provide additional control signals to second device  12  to instruct second device  12  to perform additional transmit power level adjustments. A similar procedure may be performed by devices  10  and  12  to adjust transmit power levels for EHF link  60 . If desired, first device  10  and/or second device  12  may generate and transmit a pseudo random bit sequence through windows  164  and  178  in evaluating the quality of EHF links  60  and  62 , as described above in connection with  FIG. 5  (e.g., to determine whether transmit power level adjustments need to be made or in performing any other desired characterization of links  60  and  62 ). 
     Radio-frequency circuitry  34  in first device  10  may operate on the physical layer of the Open System Interconnections (OSI) model. In general, the OSI model includes seven network protocol layers. The layers of the OSI model are stacked to form a hierarchy with the physical layer (PHY) at the first and lowest layer (Layer-1) and the application layer at the seventh and highest level of the hierarchy. Radio-frequency circuitry  34  may sometimes be referred to herein as RF PHY circuitry  34  or Layer-1 circuitry  34 . RF PHY circuitry  34  may perform Layer-1 processing operations such as beam steering operations on data received from baseband processor  32  and data received over antennas  214 . If desired, baseband processor  32  may convey data to RF PHY circuitry  34  without performing any OSI encoding operations on the data. This may allow baseband processor  32  to have a reduced size relative to RF PHY circuitry  34  and relative to scenarios where baseband processor  32  performs OSI encoding operations. 
       FIG. 10  is an illustrative diagram showing how simplified baseband processing circuitry may convey signals to RF PHY circuitry in device  10 . As shown in  FIG. 10 , baseband processor circuitry  32  may receive data for transmission over path  222 . Baseband processor circuitry  32  may be formed as a part of RF module  40  (e.g., as shown by circuitry  75  in the example of  FIG. 3 ) or may be formed separately from the module. As an example, storage and processing circuitry  16  may provide data for transmission to baseband processor  32  over path  222 . Baseband processor  32  may convey the received stream of data to RF PHY circuitry  220 . RF PHY circuitry  220  may operate on the physical layer (Layer-1) of the OSI model. RF PHY circuitry  220  may be formed on a single integrated circuit sometimes referred to herein as a physical layer chip or a PHY chip. RF PHY chip  220  may include radio-frequency circuitry  34  of the type shown in  FIGS. 1, 8, and 9 , for example. 
     Baseband processor  32  may be a simplified baseband processor that does not perform any encoding operations on the data received over path  222 . For example, baseband  32  may deliver a stream of data received over path  222  to RF PHY circuitry  220  without packetizing the data (e.g., without arranging the data into a stream of packets according to a packet-based communications protocol) or adding frame headers to the data. If desired, baseband circuitry  32  may perform amplitude-shift keying (ASK) modulation on the data received over path  222 . Performing ASK modulation on the data may represent the data as a variation in the amplitude of a carrier wave. The ASK modulated data may be transmitted to RF PHY  220 . Similarly, baseband circuitry  32  may perform ASK demodulation on data received from RF PHY circuitry  220 . If desired, baseband  32  may provide the received data to RF PHY circuitry  220  in the form of in-phase and quadrature-phase (I/Q) data. 
     RF PHY circuitry  220  may perform OSI physical layer operations on the data received from baseband  32 . If desired, RF PHY circuitry  220  may perform IEEE 802.11ad communications operations using EHF signals. For example, PHY circuitry  220  may perform IEEE 802.11ad encoding and beam steering operations associated with IEEE 802.11ad communications on the data received from baseband  32  to transmit the data over an array of antennas  214 . Because baseband  32  need not generate any packets or frame headers for the data, baseband  32  may have a reduced size relative to baseband processors that perform data packetization and relative to the size of RF PHY circuitry  220 . For example, baseband  32  may have a lateral dimension L 2  whereas RF PHY circuitry  220  has a lateral dimension L 1  that is greater than lateral dimension L 1 . As an example baseband processor  32  may have a size of 5 mm by 5 mm or smaller, whereas RF PHY circuitry  220  has a size of 10 mm by 10 mm or greater. The reduced size of baseband circuitry  32  may contribute to an overall reduction in the size of the wireless circuitry in device  10  relative to scenarios where more complex baseband circuitry is used, while still allowing complex operations such as IEEE 802.11ad beam steering to be performed. While described in connection with first device  10 , the components of  FIG. 10  may be used to form the wireless circuitry of second device  12  if desired. 
     In the examples of  FIGS. 7-9 , a single antenna window  164  is formed in device  10  for conveying both EHF communications links  60  and  62 . Conveying multiple EHF communications links through a single antenna window may remove rotational sensitivity of device  10  when communicating with other EHF devices. 
       FIG. 11  is an illustrative diagram showing how a single antenna window  164  on first device  10  may allow device  10  to be rotationally insensitive when communicating in EHF bands with an external device. As shown in  FIG. 11 , first device  10  may be communicably coupled via EHF links  60  and  62  with an external device  236 . External device  236  may be a secondary device such as device  12  as shown in  FIGS. 1, 8, and 9 . In the example of  FIG. 11 , device  236  is a peripheral mat or docking device. Primary device  10  may be placed on top of mat device  236  (e.g., by a user of device  10 ). Mat device  236  may perform wireless data synching operations with device  10  over EHF links  60  and  62  while device  10  is placed on top of mat device  236 , for example. The high data rate of links  60  and  62  may allow data synching operations to be performed much more rapidly than when lower frequency links are used. If desired, mat  236  may perform wireless charging operations on device  10  (e.g., to wirelessly charge a battery on device  10 ) or any other desired wireless operations to support device  10  when placed on top of mat  236 . 
     As shown in  FIG. 11 , peripheral device  236  may include a number of antennas  234  for conveying EHF signals. Antennas  234  may be arranged in a repeating array of antennas on the top surface of device  236 . Antennas  234  may be formed behind respective dielectric antenna windows or may be formed behind a dielectric cover for device  236 . 
     In scenarios where first device  10  has two separate antenna windows for conveying respective EHF links  60  and  62  (e.g., windows  160  as shown in  FIG. 6 ), the windows need to overlap with two corresponding antennas  234  on device  236  for the links to be properly established and for high data rate data transfer between the two devices to occur. If care is not taken when placing first device  10  onto peripheral device  236 , one of the two antenna windows may be misaligned with respect to two corresponding antennas  234  on device  236 . Such misalignment could prevent EHF links  60  and  62  from being established between devices  10  and  12 . 
     The example of  FIG. 11  shows a scenario where device  10  has a single antenna window  164  for conveying both EHF links  60  and  62  (e.g., using a frequency duplexing scheme such as that shown in  FIGS. 8 and 9 ). First device  10  may be placed at a number of different positions and orientations on device  236  such as positions  232  and  230 . Because first device  10  includes only a single antenna window  164  for conveying both EHF links  60  and  62 , device  10  may be more easily aligned with a corresponding antenna  234  on device  236  (regardless of the orientation of device  10 ) than when two separate antenna windows  160  are used. This may allow EHF links  60  and  62  to be established and maintained with peripheral device  236  regardless of the orientation and position of first device  10  on top of peripheral device  236 . In other words, forming a single antenna window  164  for conveying both EHF links  60  and  62  may allow for first device  10  to be rotationally insensitive or invariant for performing high speed data transfer operations with secondary device  236  over wireless links at frequencies greater than  10  GHz. This may, for example, allow a user of first device  10  to place device  10  onto device  236  without expending time and energy to ensure that multiple antenna windows on device  10  are aligned with two corresponding antennas on device  236 . 
     The high data rates obtainable by devices  10  and  12  for performing data transfer operations (e.g., 500 Mbps or higher, 1 bit per second or higher, 500 Mega bytes per second (MBps) or higher, etc.) may allow relatively large data files to be wireless transferred between the devices in a short or even unnoticeable amount of time relative to scenarios where lower frequencies are used. The supported high data rates may, for example, allow for first device  10  to off-load complex processing operations to secondary device  12 . For example, second device  12  may include processing circuitry having greater processing power than first device  10 . If desired, first device  10  may off-load complex processing operations to second device  12  via EHF links  60  and  62 . Second device  12  may have sufficient processing power and EHF links  60  and  62  may have sufficient bandwidth (data rates) such that second device  12  can receive data from first device  10  for processing, perform the off-loaded processing operations on the received data, and return the processed data over links  60  and  62  in less time than if first device  10  had performed the processing operations itself. By performing data transfer operations over a wireless link, bulky wired data ports can be omitted from the system. Use of a single antenna window  164  may allow for rotational invariance between devices  10  and  12  when communicating over EHF links  60  and  62 , improved device aesthetics, and reduced manufacturing complexity. Use of active transmit power feedback between devices  10  and  12  may allow for links  60  and  62  to be maintained at an optimal link quality even if the operating conditions for devices  10  and  12  change over time. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20170124
Publication Date: 20200128
Grant Date: 20200128
Priority Date: 20160129
Inventors: SHIU, Boon W.
JACOB, JOBIN
RIVERA ESPINOZA, JORGE L.
BARATZADEH, KIAVASH
SANGUINETTI, LOUIE J.
CABALLERO, RUBEN
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L5/1461", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3888", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/2291", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3888", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3888", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2291", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/1461", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 59385688