PATENT DOCUMENT

Publication Number: US-10727580-B2
Application Number: US-201816036770-A
Country: US
Kind Code: B2

Title: Millimeter wave antennas having isolated feeds

Abstract:
An electronic device may be provided with antenna structures that convey radio-frequency signals greater than 10 GHz. The antenna structures may include overlapping first and second patches. The first patch may include a hole. A transmission line for the second patch may include a conductive via extending through the hole. The via may be coupled to a first end of a trace. A second end of the trace may be coupled to a feed terminal on the second patch over an additional via. The hole may be located within a central region of the first patch to allow the via to pass through the hole without electromagnetically coupling to the first patch. If desired, adjustable impedance matching circuits may be used to couple selected impedances to the antenna feeds that help ensure that the first and second patch antennas are sufficiently isolated from each other.

Claims:
What is claimed is: 
     
       1. Antenna structures configured to radiate in first and second frequency bands higher than 10 GHz, comprising:
 a stacked dielectric substrate having a first, second, third, and fourth layers, the second layer being interposed between the first and third layers, and the third layer being interposed between the second and fourth layers; 
 a ground plane on the first layer; 
 a first conductive patch on the second layer and comprising a first positive antenna feed terminal and an opening; 
 a second conductive patch on the fourth layer and comprising a second positive antenna feed terminal; and 
 a transmission line comprising a first conductive via coupled to the second positive antenna feed terminal, a second conductive via extending through the opening, and a conductive trace on the third layer that couples the first conductive via to the second conductive via. 
 
     
     
       2. The antenna structures defined in  claim 1 , wherein the first conductive patch is configured to generate an electric field and the opening is aligned with a location on the first conductive patch at which the generated electric field exhibits a minimum magnitude. 
     
     
       3. The antenna structures defined in  claim 2 , wherein the first conductive patch has a length and the location on the first conductive patch is halfway across the length. 
     
     
       4. The antenna structures defined in  claim 1 , wherein the conductive trace has a length configured to match an impedance of the second conductive patch to an impedance of the transmission line. 
     
     
       5. The antenna structures defined in  claim 1 , wherein the first conductive patch comprises an additional opening and the second conductive patch comprises a third positive antenna feed terminal, the antenna structures further comprising:
 an additional transmission line that includes a third conductive via coupled to the third positive antenna feed terminal, a fourth conductive via extending through the additional opening, and an additional conductive trace on the third layer that couples the third conductive via to the fourth conductive via. 
 
     
     
       6. The antenna structures defined in  claim 5 , wherein the first conductive patch comprises a fourth positive antenna feed terminal, the first and second positive antenna feed terminals are configured to convey radio-frequency signals with a first polarization, and the third and fourth positive antenna feed terminals are configured to convey radio-frequency signals with a second polarization orthogonal to the first polarization. 
     
     
       7. The antenna structures defined in  claim 1 , further comprising:
 a hole in the ground plane that is aligned with the opening in the first conductive patch, wherein the second conductive via extends through the first layer, the hole, the second layer, and the third layer, and the first conductive via extends through the fourth layer. 
 
     
     
       8. The antenna structures defined in  claim 1 , wherein the dielectric substrate comprises a fifth layer, the first layer is interposed between the fifth and second layers, and the transmission line further comprises an additional conductive trace on the fifth layer that is coupled to the second conductive via. 
     
     
       9. The antenna structures defined in  claim 1 , further comprising:
 an additional transmission line that includes a third conductive via coupled to the first positive antenna feed terminal. 
 
     
     
       10. The antenna structures defined in  claim 1 , wherein the first conductive patch is configured to radiate in the first frequency band, the second conductive patch is configured to radiate in the second frequency band, and the second frequency band is higher than the first frequency band. 
     
     
       11. The antenna structures defined in  claim 10 , wherein the first frequency band comprises a frequency band between 27.5 GHz and 29.5 GHz and the second frequency band comprises a frequency band between 37 GHz and 41 GHz. 
     
     
       12. An electronic device comprising:
 radio-frequency transceiver circuitry configured to transmit radio-frequency signals at a frequency between 10 GHz and 300 GHz; 
 a first patch antenna resonating element having a central region with a hole; 
 a second patch antenna resonating element at least partially overlapping the first patch antenna resonating element and having a positive antenna feed terminal; 
 a first conductive via extending through the hole; 
 a second conductive via coupled to the positive antenna feed terminal and laterally offset with respect to the first conductive via; and 
 a conductive path coupled between the first and second conductive vias, wherein the first conductive via, the conductive path, and the second conductive via are configured to convey the radio-frequency signals transmitted by the radio-frequency transceiver circuitry to the positive antenna feed terminal.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices often include wireless communications circuitry. For example, cellular telephones, computers, and other devices often contain antennas and wireless transceivers for supporting wireless communications. 
     It may be desirable to support wireless communications in millimeter wave and centimeter wave communications bands. Millimeter wave communications, which are sometimes referred to as extremely high frequency (EHF) communications, and centimeter wave communications involve communications at frequencies of about 10-300 GHz. Operation at these frequencies may support high bandwidths, but may raise significant challenges. For example, millimeter wave communications signals generated by antennas can be characterized by substantial attenuation and/or distortion during signal propagation. In addition, it can be difficult to ensure that multiple antennas for handling millimeter wave communications are sufficiently isolated from each other. 
     It would therefore be desirable to be able to provide electronic devices with improved wireless communications circuitry such as communications circuitry that supports millimeter and centimeter wave communications. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antenna structures and transceiver circuitry such as millimeter wave transceiver circuitry. Antenna structures in the wireless circuitry may include co-located patch antennas that are organized in a phased antenna array. 
     The antenna structures may include first and second patch antennas. The first patch antenna may include a first patch antenna resonating element over a ground plane. The second patch antenna may include a second patch antenna resonating element that at least partially overlaps the first patch antenna resonating element. The first patch antenna resonating element may convey radio-frequency signals in a first frequency band higher than 10 GHz. The second patch antenna resonating element may convey radio-frequency signals in a second frequency band higher than 10 GHz. The first patch antenna resonating element may include a hole. A transmission line for the second patch antenna resonating element may include a conductive via extending through the hole. The first and second patch antenna resonating elements may each include two positive antenna feed terminals for conveying radio-frequency signals with orthogonal polarizations. 
     In one suitable arrangement, the conductive via may be coupled to a first end of a conductive trace between the first and second patch antenna resonating elements. A second end of the conductive trace may be coupled to a positive antenna feed terminal on the second patch antenna resonating element over an additional conductive via. The additional conductive via may be laterally offset from the conductive via extending through the hole to ensure that the second patch antenna resonating element is impedance matched to the transmission line. The hole may be located within a central region of the first patch antenna resonating element (e.g., a location at which the first patch antenna resonating element generates an electric field with minimum magnitude). This may allow the conductive via to pass through the hole without electromagnetically coupling to the first patch antenna resonating element, thereby ensuring that the first and second patch antennas as sufficiently isolated. 
     In another suitable arrangement, adjustable impedance matching circuits may be coupled to the antenna feeds for the first and second patch antennas. The first and second patch antennas may be embedded in a substrate. The impedance matching circuits may be mounted to a surface of the substrate and may be coupled to the antenna feeds over corresponding conductive matching vias. If desired, the impedance matching circuits may be formed in an integrated circuit mounted to the substrate. Impedance matching circuits in the integrated circuit may be coupled to radio-frequency ports of the integrated circuit. Control circuitry may adjust the impedance matching circuits to couple selected impedances to the antenna feeds that help to ensure that the first and second patch antennas are sufficiently isolated from each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 3  is a rear perspective view of an illustrative electronic device showing illustrative locations at which antennas for communications at frequencies greater than 10 GHz may be located in accordance with an embodiment. 
         FIG. 4  is a diagram of an illustrative transceiver circuit and antenna in accordance with an embodiment. 
         FIG. 5  is a perspective view of an illustrative patch antenna in accordance with an embodiment. 
         FIG. 6  is a perspective view of an illustrative patch antenna with dual ports in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of illustrative multi-band antenna structures having co-located patch antennas with isolated feeds in accordance with an embodiment. 
         FIG. 8  is a top-down view of illustrative multi-band antenna structures having co-located patch antennas with isolated feeds in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view showing how adjustable matching circuits may be provided for multi-band antenna structures having co-located patch antennas to enhance feed isolation in accordance with an embodiment. 
         FIGS. 10-12  are circuit diagrams of illustrative components that may be used to form adjustable matching circuits of the type shown in  FIG. 9  in accordance with an embodiment. 
         FIG. 13  is a graph of isolation between co-located patch antennas of the types shown in  FIGS. 7-9  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may contain wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include phased antenna arrays that are used for handling millimeter wave and centimeter wave communications. Millimeter wave communications, which are sometimes referred to as extremely high frequency (EHF) communications, involve signals at 60 GHz or other frequencies between about 30 GHz and 300 GHz. Centimeter wave communications involve signals at frequencies between about 10 GHz and 30 GHz. If desired, device  10  may also contain wireless communications circuitry for handling satellite navigation system signals, cellular telephone signals, local wireless area network signals, near-field communications, light-based wireless communications, or other wireless communications. 
     Electronic 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 wristwatch device, a pendant device, a headphone or earpiece device, a virtual or augmented reality headset device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, a wireless access point or base station, a desktop computer, a keyboard, a gaming controller, a computer mouse, a mousepad, a trackpad or touchpad, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     As shown in  FIG. 1 , device  10  may include a display such as display  8 . Display  8  may be mounted in a housing such as housing  12 . Housing  12 , 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  12  may be formed using a unibody configuration in which some or all of housing  12  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.). 
     Display  8  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  8  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  8  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, openings may be formed in the display cover layer to accommodate one or more buttons, sensor circuitry such as a fingerprint sensor or light sensor, ports such as a speaker port or microphone port, etc. Openings may be formed in housing  12  to form communications ports (e.g., an audio jack port, a digital data port, charging port, etc.). Openings in housing  12  may also be formed for audio components such as a speaker and/or a microphone. 
     Antennas may be mounted in housing  12 . If desired, some of the antennas (e.g., antenna arrays that may implement beam steering, etc.) may be mounted under an inactive border region of display  8  (see, e.g., illustrative antenna locations  6  of  FIG. 1 ). Display  8  may contain an active area with an array of pixels (e.g., a central rectangular portion). Inactive areas of display  8  are free of pixels and may form borders for the active area. If desired, antennas may also operate through dielectric-filled openings in the rear of housing  12  or elsewhere in device  10 . 
     To avoid disrupting communications when an external object such as a human hand or other body part of a user blocks one or more antennas, antennas may be mounted at multiple locations in housing  12 . Sensor data such as proximity sensor data, real-time antenna impedance measurements, signal quality measurements such as received signal strength information, and other data may be used in determining when one or more antennas is being adversely affected due to the orientation of housing  12 , blockage by a user&#39;s hand or other external object, or other environmental factors. Device  10  can then switch one or more replacement antennas into use in place of the antennas that are being adversely affected. 
     Antennas may be mounted at the corners of housing  12  (e.g., in corner locations  6  of  FIG. 1  and/or in corner locations on the rear of housing  12 ), along the peripheral edges of housing  12 , on the rear of housing  12 , under the display cover glass or other dielectric display cover layer that is used in covering and protecting display  8  on the front of device  10 , under a dielectric window on a rear face of housing  12  or the edge of housing  12 , or elsewhere in device  10 . 
     A schematic diagram showing illustrative components that may be used in device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include storage and processing circuitry such as control circuitry  14 . Control circuitry  14  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  14  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processor integrated circuits, application specific integrated circuits, etc. 
     Control circuitry  14  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, control circuitry  14  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  14  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other WPAN protocols, IEEE 802.11ad protocols, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols, etc. 
     Device  10  may include input-output circuitry  16 . Input-output circuitry  16  may include input-output devices  18 . Input-output devices  18  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  18  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, accelerometers or other components that can detect motion and device orientation relative to the Earth, capacitance sensors, proximity sensors (e.g., a capacitive proximity sensor and/or an infrared proximity sensor), magnetic sensors, and other sensors and input-output components. 
     Input-output circuitry  16  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas  40 , transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include transceiver circuitry  20  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  22 ,  24 ,  26 , and  28 . 
     Transceiver circuitry  24  may be wireless local area network (WLAN) transceiver circuitry. Transceiver circuitry  24  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. 
     Circuitry  34  may use cellular telephone transceiver circuitry  26  for handling wireless communications in frequency ranges such as a communications band from 700 to 960 MHz, a communications band from 1710 to 2170 MHz, and a communications band from 2300 to 2700 MHz or other communications bands between 700 MHz and 4000 MHz or other suitable frequencies (as examples). Circuitry  26  may handle voice data and non-voice data. 
     Millimeter wave transceiver circuitry  28  (sometimes referred to as extremely high frequency (EHF) transceiver circuitry  28  or transceiver circuitry  28 ) may support communications at frequencies between about 10 GHz and 300 GHz. For example, transceiver circuitry  28  may support communications in Extremely High Frequency (EHF) or millimeter wave communications bands between about 30 GHz and 300 GHz and/or in centimeter wave communications bands between about 10 GHz and 30 GHz (sometimes referred to as Super High Frequency (SHF) bands). As examples, transceiver circuitry  28  may support communications in an IEEE K communications band between about 18 GHz and 27 GHz, a K a  communications band between about 26.5 GHz and 40 GHz, a K u  communications band between about 12 GHz and 18 GHz, a V communications band between about 40 GHz and 75 GHz, a W communications band between about 75 GHz and 110 GHz, or any other desired frequency band between approximately 10 GHz and 300 GHz. If desired, circuitry  28  may support IEEE 802.11ad communications at 60 GHz and/or 5 th  generation mobile networks or 5 th  generation wireless systems (5G) communications bands between 27 GHz and 90 GHz. If desired, circuitry  28  may support communications at multiple frequency bands between 10 GHz and 300 GHz such as a first band from 27.5 GHz to 29.5 GHz, a second band from 37 GHz to 41 GHz, and a third band from 57 GHz to 71 GHz, or other communications bands between 10 GHz and 300 GHz. Circuitry  28  may be formed from one or more integrated circuits (e.g., multiple integrated circuits mounted on a common printed circuit in a system-in-package device, one or more integrated circuits mounted on different substrates, etc.). While circuitry  28  is sometimes referred to herein as millimeter wave transceiver circuitry  28 , millimeter wave transceiver circuitry  28  may handle communications at any desired communications bands at frequencies between 10 GHz and 300 GHz (e.g., in millimeter wave communications bands, centimeter wave communications bands, etc.). 
     Wireless communications circuitry  34  may include satellite navigation system circuitry such as Global Positioning System (GPS) receiver circuitry  22  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., GLONASS signals at 1609 MHz). Satellite navigation system signals for receiver  22  are received from a constellation of satellites orbiting the earth. 
     In satellite navigation system links, cellular telephone links, and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. In WiFi® and Bluetooth® links at 2.4 and 5 GHz and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. Extremely high frequency (EHF) wireless transceiver circuitry  28  may convey signals over short distances that travel between transmitter and receiver over a line-of-sight path. To enhance signal reception for millimeter and centimeter wave communications, phased antenna arrays and beam steering techniques may be used (e.g., schemes in which antenna signal phase and/or magnitude for each antenna in an array is adjusted to perform beam steering). Antenna diversity schemes may also be used to ensure that the antennas that have become blocked or that are otherwise degraded due to the operating environment of device  10  can be switched out of use and higher-performing antennas used in their place. 
     Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. 
     Antennas  40  in wireless communications circuitry  34  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from stacked patch antenna structures, loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, monopoles, dipoles, helical antenna structures, Yagi (Yagi-Uda) antenna structures, hybrids of these designs, etc. If desired, one or more of antennas  40  may be cavity-backed antennas. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. Dedicated antennas may be used for receiving satellite navigation system signals or, if desired, antennas  40  can be configured to receive both satellite navigation system signals and signals for other communications bands (e.g., wireless local area network signals and/or cellular telephone signals). Antennas  40  can one or more antennas such as antennas arranged in one or more phased antenna arrays for handling millimeter and centimeter wave communications. 
     Transmission line paths may be used to route antenna signals within device  10 . For example, transmission line paths may be used to couple antenna structures  40  to transceiver circuitry  20 . Transmission lines in device  10  may include coaxial probes realized by metalized vias, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, waveguide structures, transmission lines formed from combinations of transmission lines of these types, etc. Transmission lines in device  10  may be integrated into rigid and/or flexible printed circuit boards. In one suitable arrangement, transmission lines in device  10  may also include transmission line conductors (e.g., signal and ground conductors) integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive) that may be folded or bent in multiple dimensions (e.g., two or three dimensions) and that maintain a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). All of the multiple layers of the laminated structures may be batch laminated together (e.g., in a single pressing process) without adhesive (e.g., as opposed to performing multiple pressing processes to laminate multiple layers together with adhesive). Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within the transmission lines, if desired. 
     In devices such as handheld devices, the presence of an external object such as the hand of a user or a table or other surface on which a device is resting has a potential to block wireless signals such as millimeter wave signals. Accordingly, it may be desirable to incorporate multiple antennas or phased antenna arrays into device  10 , each of which is placed in a different location within device  10 . With this type of arrangement, an unblocked antenna or phased antenna array may be switched into use. In scenarios where a phased antenna array is formed in device  10 , once switched into use, the phased antenna array may use beam steering to optimize wireless performance. Configurations in which antennas from one or more different locations in device  10  are operated together may also be used. 
       FIG. 3  is a rear perspective view of electronic device  10  showing illustrative locations  50  on the rear and sides of housing  12  in which antennas  40  (e.g., single antennas and/or phased antenna arrays for use with wireless circuitry  34  such as wireless transceiver circuitry  28 ) may be mounted in device  10 . Antennas  40  may be mounted at the corners of device  10 , along the edges of housing  12  such as edge  12 E, on upper and lower portions of rear housing portion (wall)  12 R, in the center of rear housing wall  12 R (e.g., under a dielectric window structure or other antenna window in the center of rear housing  12 R), at the corners of rear housing wall  12 R (e.g., on the upper left corner, upper right corner, lower left corner, and lower right corner of the rear of housing  12  and device  10 ), etc. 
     In configurations in which housing  12  is formed entirely or nearly entirely from a dielectric, antennas  40  may transmit and receive antenna signals through any suitable portion of the dielectric. In configurations in which housing  12  is formed from a conductive material such as metal, regions of the housing such as slots or other openings in the metal may be filled with plastic or other dielectric. Antennas  40  may be mounted in alignment with the dielectric in the openings. These openings, which may sometimes be referred to as dielectric antenna windows, dielectric gaps, dielectric-filled openings, dielectric-filled slots, elongated dielectric opening regions, etc., may allow antenna signals to be transmitted to external equipment from antennas  40  mounted within the interior of device  10  and may allow internal antennas  40  to receive antenna signals from external equipment. In another suitable arrangement, antennas  40  may be mounted on the exterior of conductive portions of housing  12 . 
     In devices with phased antenna arrays, circuitry  34  may include gain and phase adjustment circuitry that is used in adjusting the signals associated with each antenna  40  in an array (e.g., to perform beam steering). Switching circuitry may be used to switch desired antennas  40  into and out of use. If desired, each of locations  50  may include multiple antennas  40  (e.g., a set of three antennas or more than three or fewer than three antennas in a phased antenna array) and, if desired, one or more antennas from one of locations  50  may be used in transmitting and receiving signals while using one or more antennas from another of locations  50  in transmitting and receiving signals. 
     A schematic diagram of an antenna  40  coupled to transceiver circuitry  20  (e.g., transceiver circuitry  28  of  FIG. 2 ) is shown in  FIG. 4 . As shown in  FIG. 4 , radio-frequency transceiver circuitry  20  may be coupled to antenna feed  100  of antenna  40  using transmission line  64 . Antenna feed  100  may include a positive antenna feed terminal such as positive antenna feed terminal  96  and may include a ground antenna feed terminal such as ground antenna feed terminal  98 . Transmission line  64  may be formed form metal traces on a printed circuit or other conductive structures and may have a positive transmission line signal path such as path  91  that is coupled to terminal  96  and a ground transmission line signal path such as path  94  that is coupled to terminal  98 . Path  91  may sometimes be referred to herein as signal conductor  91 . Path  94  may sometimes be referred to herein as ground conductor  94 . 
     Transmission line paths such as path  64  may be used to route antenna signals within device  10 . For example, transmission line paths may be used to couple antenna structures such as one or more antennas in an array of antennas to transceiver circuitry  20 . Transmission lines in device  10  may include coaxial probes realized by metal vias, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, waveguide structures, transmission lines formed from combinations of transmission lines of these types, etc. Transmission lines in device  10  may be integrated into rigid and/or flexible printed circuit boards. 
     In one suitable arrangement, transmission lines in device  10  may also include transmission line conductors (e.g., signal and ground conductors) integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive) that may be folded or bent in multiple dimensions (e.g., two or three dimensions) and that maintain a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within transmission line  64  and/or circuits such as these may be incorporated into antenna  40  if desired (e.g., to support antenna tuning, to support operation in desired frequency bands, etc.). 
     Device  10  may contain multiple antennas  40 . The antennas may be used together or one of the antennas may be switched into use while other antenna(s) are switched out of use. If desired, control circuitry  14  ( FIG. 2 ) may be used to select an optimum antenna to use in device  10  in real time and/or to select an optimum setting for adjustable wireless circuitry associated with one or more of antennas  40 . Antenna adjustments may be made to tune antennas to perform in desired frequency ranges, to perform beam steering with a phased antenna array, and to otherwise optimize antenna performance. Sensors may be incorporated into antennas  40  to gather sensor data in real time that is used in adjusting antennas  40 . 
     In some configurations, antennas  40  may be arranged in one or more antenna arrays (e.g., phased antenna arrays to implement beam steering functions). For example, the antennas that are used in handling millimeter and centimeter wave signals wireless transceiver circuits  28  may be implemented as phased antenna arrays. The radiating elements in a phased antenna array for supporting millimeter and centimeter wave communications may be patch antennas (e.g., stacked patch antennas), dipole antennas, dipole antennas with directors and reflectors in addition to dipole antenna resonating elements (sometimes referred to as Yagi antennas or beam antennas), or other suitable antenna elements. Transceiver circuitry can be integrated with the phased antenna arrays to form integrated phased antenna array and transceiver circuit modules. 
     An illustrative patch antenna that may be used in conveying wireless signals at frequencies between 10 GHz and 300 GHz or other wireless signals is shown in  FIG. 5 . As shown in  FIG. 5 , antenna  40  may be a patch antenna having a patch antenna resonating element  104  that is separated from and parallel to a ground plane such as antenna ground plane  92 . Positive antenna feed terminal  96  may be coupled to patch antenna resonating element  104 . Ground antenna feed terminal  98  may be coupled to ground plane  92 . If desired, conductive path  88  (e.g., a coaxial probe feed) may be used to couple terminal  96 ′ to terminal  96  so that antenna  40  is fed using a transmission line with a positive conductor coupled to terminal  96 ′ and thus terminal  96 . If desired, path  88  may be omitted and other types of antenna feed arrangements may be used. The illustrative feeding configuration of  FIG. 5  is merely illustrative. 
     As shown in  FIG. 5 , patch antenna resonating element  104  may lie within a plane such as the X-Y plane of  FIG. 5  (e.g., the lateral surface area of element  104  may lie in the X-Y plane). Patch antenna resonating element  104  may sometimes be referred to herein as patch  104 , patch element  104 , patch resonating element  104 , antenna resonating element  104 , or resonating element  104 . Ground plane  92  may lie within a plane that is parallel to the plane of patch  104 . Patch  104  and ground plane  92  may therefore lie in separate parallel planes that are separated by a distance H. Patch  104  and ground plane  92  may be formed from conductive traces patterned on a dielectric substrate such as a rigid or flexible printed circuit board substrate, metal foil, stamped sheet metal, electronic device housing structures, or any other desired conductive structures. The length of the sides of patch  104  may be selected so that antenna  40  resonates at a desired operating frequency. For example, the sides of patch  104  may each have a length L 0  that is approximately equal to half of the wavelength (e.g., within 15% of half of the wavelength) of the signals conveyed by antenna  40  (e.g., in scenarios where patch  104  is substantially square). 
     The example of  FIG. 5  is merely illustrative. Patch  104  may have a square shape in which all of the sides of patch  104  are the same length or may have a different rectangular shape (e.g., a non-square rectangular shape). If desired, patch  104  and ground plane  92  may have different shapes and orientations (e.g., planar shapes, curved patch shapes, patch shapes with non-rectangular outlines, shapes with straight edges such as squares, shapes with curved edges such as ovals and circles, shapes with combinations of curved and straight edges, etc.). In scenarios where patch  104  is non-rectangular, patch  104  may have a side or a maximum lateral dimension that is approximately equal to (e.g., within 15% of) half of the wavelength of operation, for example. 
     To enhance the polarizations handled by antenna  40 , antenna  40  may be provided with multiple feeds. An illustrative patch antenna with multiple feeds is shown in  FIG. 6 . As shown in  FIG. 6 , antenna  40  may have a first feed at antenna port P 1  that is coupled to transmission line  64 - 1  and a second feed at antenna port P 2  that is coupled to transmission line  64 - 2 . The first antenna feed may have a first ground feed terminal coupled to antenna ground  92  and a first positive antenna feed terminal  96 -P 1  coupled to patch  104 . The second antenna feed may have a second ground feed terminal coupled to ground plane  92  and a second positive antenna feed terminal  96 -P 2  on patch  104 . 
     Patch  104  may have a rectangular shape with a first pair of edges running parallel to dimension Y and a second pair of perpendicular edges running parallel to dimension X, for example. The length of patch  104  in dimension Y is L 1  and the length of patch  104  in dimension X is L 2 . With this configuration, antenna  40  may be characterized by orthogonal polarizations. 
     When using the first antenna feed associated with port P 1 , antenna  40  may transmit and/or receive antenna signals in a first communications band at a first frequency (e.g., a frequency at which one-half of the corresponding wavelength is approximately equal to dimension L 1 ). These signals may have a first polarization (e.g., the electric field E 1  of antenna signals  102  associated with port P 1  may be oriented parallel to dimension Y). When using the antenna feed associated with port P 2 , antenna  40  may transmit and/or receive antenna signals in a second communications band at a second frequency (e.g., a frequency at which one-half of the corresponding wavelength is approximately equal to dimension L 2 ). These signals may have a second polarization (e.g., the electric field E 2  of antenna signals  102  associated with port P 2  may be oriented parallel to dimension X so that the polarizations associated with ports P 1  and P 2  are orthogonal to each other). In scenarios where patch  104  is square (e.g., length L 1  is equal to length L 2 ), ports P 1  and P 2  may cover the same communications band. In scenarios where patch  104  is rectangular, ports P 1  and P 2  may cover different communications bands if desired. During wireless communications using device  10 , device  10  may use port P 1 , port P 2 , or both port P 1  and P 2  to transmit and/or receive signals (e.g., millimeter wave signals at millimeter wave frequencies). 
     The example of  FIG. 6  is merely illustrative. Patch  104  may have a square shape in which all of the sides of patch  104  are the same length or may have a rectangular shape in which length L 1  is different from length L 2 . In general, patch  104  and ground plane  92  may have different shapes and orientations (e.g., planar shapes, curved patch shapes, patch element shapes with non-rectangular outlines, shapes with straight edges such as squares, shapes with curved edges such as ovals and circles, shapes with combinations of curved and straight edges, etc.). 
     If care is not taken, antennas  40  such as single-polarization patch antennas of the type shown in  FIG. 5  and/or dual-polarization patch antennas of the type shown in  FIG. 6  may have insufficient bandwidth for covering an entirety of a communications band of interest (e.g., a communications band at frequencies greater than 10 GHz). If desired, antenna  40  may include one or more parasitic antenna resonating elements that serve to broaden the bandwidth of antenna  40 . The parasitic antenna resonating element may be formed from one or more patches over patch  104 . The length of the parasitic antenna resonating element may be greater than or less than the length of patch  104  to add additional resonances that broaden the bandwidth of the antenna. The parasitic antenna resonating element may have a cross shape for impedance matching if desired. 
     Antennas  40  such as single-polarization patch antennas of the type shown in  FIG. 5  and/or dual-polarization patch antennas of the type shown in  FIG. 6  may be arranged within a corresponding phased antenna array in device  10  if desired. In practice, it may be desirable for antennas  40  within device  10  to be able to provide coverage in multiple communications bands between 10 GHz and 300 GHz. As examples, the communications bands may include millimeter and/or centimeter wave frequencies from 27.5 GHz to 28.5 GHz, from 26 GHz to 30 GHz, from 20 to 36 GHz, from 37 GHz to 41 GHz, from 36 GHz to 42 GHz, from 30 GHz to 56 GHz, from 57 GHz to 71 GHz, from 58 GHz to 63 GHz, from 59 GHz to 61 GHz, from 42 GHz to 71 GHz, or any other desired bands of frequencies between 10 GHz and 300 GHz. In one suitable arrangement that is described herein as an example, it may be desirable for the antennas to cover both a first communications band between 27.5 and 29.5 GHz and a second communications band between 37 GHz to 41 GHz. Patch  104  as shown in  FIGS. 5 and 6  may have insufficient bandwidth to cover the entirety of the frequency range between 27.5 GHz and 41 GHz. 
     In some scenarios, a first antenna for covering the first communications band is formed at a first location and a second antenna for covering the second communications band is formed at a second location in the electronic device (e.g., first and second locations on opposing sides of the device). While a relatively large separation between the two antennas may enhance isolation between the antennas, forming the antennas at separate locations may occupy an excessive amount of the limited space within device  10 . In order to reduce the amount of space required within device  10  for covering both the first and second frequency bands, the first antenna may be co-located with the second antenna in device  10 . First and second antennas  40  may be considered to be co-located within device  10  when at least some of the patch  104  of the first antenna overlaps the outline or footprint (lateral area) of the patch  104  in the second antenna. Co-locating the antennas in this way may optimize the amount of space required by the antennas in device  10  for covering both the first and second communications bands. 
       FIG. 7  is a cross-sectional side view showing how a first antenna for covering the first communications band may be co-located with a second antenna for covering the second communications band. As shown in  FIG. 7 , antenna structures  70  may include a first antenna  40  such as antenna  40 A and a second antenna  40  such as antenna  40 B. Antenna  40 A may cover the first communications band whereas antenna  40 B covers the second communications band. Antenna structures  70  may collectively cover both the first and second communications bands. The second communications band covered by antenna  40 B may include higher frequencies (e.g., frequencies between 37 GHz and 41 GHz) than the first communications band covered by antenna  40 A (e.g., frequencies between 27.5 GHz and 29.5 GHz), for example. 
     In the example of  FIG. 7 , antenna  40 A is a patch antenna such as the single-polarization patch antenna shown in  FIG. 5  or the dual-polarization patch antenna shown in  FIG. 6 . Similarly, antenna  40 B is a patch antenna such as the single-polarization patch antenna shown in  FIG. 5  or the dual-polarization patch antenna shown in  FIG. 6 . This is merely illustrative and, if desired, antennas  40 A and  40 B may be formed using other antenna structures. Antenna structures  70  may sometimes be referred to herein as antenna system  70 , multi-band antenna system  70 , dual-band antenna system  70 , multi-band antenna structures  70 , patch antenna structures  70 , multi-band patch antenna structures  70 , co-located patch antenna structures  70 , or co-located antenna structures  70 . Antennas  40 A and  40 B may sometimes be referred to collectively herein as co-located antennas or co-located patch antennas  40 A and  40 B. 
     As shown in  FIG. 7 , patch antenna  40 A may include patch  104 A, ground plane  92 , and an antenna feed that includes a positive antenna feed terminal  96 A coupled to patch  104 A and a corresponding ground antenna feed terminal coupled to ground plane  92 . Patch antenna  40 B may include patch  104 B, ground plane  92 , and an antenna feed that includes a positive antenna feed terminal  96 B coupled to patch  104 B and a corresponding ground antenna feed terminal coupled to ground plane  92 . 
     Patch  104 A may have a lateral surface extending in the X-Y plane of  FIG. 7  and may be separated from antenna ground plane  92  by distance H (e.g., the lateral surface of patch  104 A may extend parallel to the lateral surface of ground plane  92 ). Patch  104 B may have a lateral surface extending in the X-Y plane and may be separated from patch  104 A by distance H′ (e.g., the lateral surface of patch  104 B may extend parallel to the lateral surface of ground plane  92  and patch  104 A). Distance H′ may be the same as distance H, less than distance H, or greater than distance H (e.g., patch  104 B may be separated from ground plane  92  by distance H+H′). Distances H and H′ may be between 0.1 mm and 10 mm, as examples. In general, adjusting distances H and H′ may serve to adjust the bandwidth of antennas  40 A and  40 B, respectively. 
     Antennas  40 A and  40 B may be formed on a dielectric substrate such as substrate  120 . Substrate  120  may be, for example, a rigid or printed circuit board or other dielectric substrate. Substrate  120  may include multiple dielectric layers  122  (e.g., multiple layers ceramic or multiple layers of printed circuit board substrate such fiberglass-filled epoxy). Dielectric layers  122  may include a first dielectric layer  122 - 1 , a second dielectric layer  122 - 2  over the first dielectric layer, a third dielectric layer  122 - 3  over the second dielectric layer, a fourth dielectric layer  122 - 4  over the third dielectric layer, a fifth dielectric layer  122 - 5  over the fourth dielectric layer, and a sixth dielectric layer  122 - 6  over the fifth dielectric layer. Additional dielectric layers  122  may be stacked within substrate  120  if desired. 
     With this type of arrangement, antenna  40 A may be embedded within the dielectric layers of substrate  120 . For example, ground plane  92  may be formed on a surface of second dielectric layer  122 - 2  whereas patch  104 A is formed on a surface of third dielectric layer  122 - 3 . Antenna  40 A may be fed using a first transmission line such as transmission line  64 A. Transmission line  64 A may, for example, be formed from a conductive trace such as conductive trace  126 A on dielectric layer  122 - 1  and portions of ground plane  92 . Conductive trace  126 A may form the signal conductor for transmission line  64 A (e.g., signal conductor  91  of  FIG. 3 ). A first hole  128 A may be formed in ground plane  92 . First transmission line  64 A may include a vertical conductive through-via  124 A that extends from trace  126 A through dielectric layer  122 - 2 , hole  128 A in ground plane  92 , and dielectric layer  122 - 3  to positive antenna feed terminal  96 A on patch  104 A. This example is merely illustrative and, if desired, other transmission line structures may be used (e.g., coaxial cable structures, stripline transmission line structures, etc.). 
     Patch antenna  40 B may be embedded within the layers of substrate  120 . For example, patch  104 B may be formed on a surface of dielectric layer  122 - 5 . Some or all of the lateral area of patch  104 B may overlap with the outline (footprint) of patch  104 A (in the X-Y plane). Antenna  40 B may be fed using a second transmission line such as transmission line  64 B. Transmission line  64 B may, for example, be formed from a conductive trace such as conductive trace  126 B on dielectric layer  122 - 1  and portions of ground plane  92 . Conductive trace  126 B may form the positive signal conductor for transmission line  64 B (e.g., signal conductor  91  of  FIG. 3 ). 
     A second hole  128 B may be formed in ground plane  92 . A hole  130  may be formed in patch  104 A. Second transmission line  64 B may include a vertical conductive through via  124 B that extends from trace  126 B through dielectric layer  122 - 2 , hole  128 B in ground plane  92 , dielectric layer  122 - 3 , hole  130  in patch  104 A, and dielectric layer  122 - 4  to a first end of conductive trace  134  on dielectric layer  122 - 4 . An opposing second end of conductive trace  134  may be coupled to positive antenna feed terminal  96 B on patch  104 B by a vertical conductive through-via  138  extending through dielectric layer  122 - 5 . Conductive trace  134  may sometimes be referred to herein as feed trace  134 , signal conductor trace  134 , horizontal feed trace  134 , or horizontal trace  134 . 
     In this way, ground plane  92 , trace  126 B, conductive via  124 B, horizontal trace  134 , and conductive via  138  may form part of transmission line  64 B for antenna  40 B (e.g., the signal conductor for transmission line  64 B may include trace  126 B, conductive via  124 B, horizontal trace  134 , and conductive via  138 ). Horizontal trace  134  may have a length  136  extending from the first end of the horizontal trace to the second end of the horizontal trace (e.g., conductive via  138  may be laterally offset from conductive via  124 B by length  136 ). 
     The example of  FIG. 7  is merely illustrative and, if desired, conductive vias  124 A,  124 B, and/or  138  may be replaced by any desired vertical conductive structures (e.g., metal pillars, metal wire, conductive pins, or other vertical conductive interconnect structures). If desired, other transmission line structures may be used (e.g., coaxial cable structures, stripline transmission line structures, etc.). Traces  126 A and  126 B may be formed on different dielectric layers  122  if desired. Conductive vias  124 A and  124 B may extend through the same hole in ground plane  92  if desired. Holes  128 A,  128 B, and  130  may sometimes be referred to herein as notches, gaps, openings, or slots. If desired, antenna  40 B may include one or more parasitic antenna resonating elements that serve to broaden the bandwidth of antenna  40 B (e.g., parasitic antenna resonating elements formed from one or more layers of conductive traces over patch  104 B). 
     If desired, additional dielectric layers  122  may be interposed between traces  126 A and  126 B and ground plane  92 , between ground plane  92  and patch  104 A, between patch  104 A and patch  104 B, between patch  104 A and horizontal trace  134 , between horizontal trace  134  and patch  104 B, and/or over patch  104 B. In another suitable arrangement, substrate  120  may be formed from a single dielectric layer (e.g., antennas  40 A and  40 B may be embedded within a single dielectric layer such as a molded plastic layer). In yet another suitable arrangement, substrate  120  may be omitted and antennas  40 A and  40 B may be formed on other substrate structures or may be formed without substrates. 
     In practice, while patch  104 B covers relatively high frequencies, patch  104 B may have insufficient bandwidth for covering relatively low frequencies (e.g., patch  104 B alone may not have sufficient bandwidth to cover an entirety of the frequency range from 27.5 GHz to 41 GHz). Patch  104 B may have a length (e.g., lengths L 1  and/or L 2  of  FIG. 6  and measured parallel to the X-axis of  FIG. 7 ) that configures antenna  40 B to radiate within a relatively high communications band such as a communications band between 37 GHz and 41 GHz. Patch  104 A may have a greater length that configures antenna  40 A to radiate within a relatively low communications band such as the communications band between 27.5 and 29.5 GHz. Collectively, antennas  40 A and  40 B may cover frequencies within both communications bands. 
     The electric field generated by antenna  40 A varies across the length of patch  104 A. As shown in  FIG. 7 , graph  131  plots the electric field distribution of antenna  40 A as a function location X across the length of patch  104 A (e.g., parallel to the X-axis of  FIG. 7 ). The left edge of patch  104 A corresponds to a position of X=0 whereas the right edge of patch  104 A corresponds to a position of X=X 2 . X 2  may be approximately equal to one-half of the wavelength corresponding to a frequency in the communications band covered by antenna  40 A (e.g., a frequency between 27.5 and 29.5 GHz). Curve  132  represents the electric field generated by antenna  40 A across the length of patch  104 A. As shown by curve  132 , antenna  40 A generates a maximum electric field magnitude (density) at the left edge (X=0) and at the right edge (X=X 2 ) of patch  104 A. At location X=X 1 , antenna  40 A generates an electric field having zero magnitude. Location X=X 1  may be located at the center of patch  104 B (e.g., X 1  may be equal to X 2 /2 and one-quarter of the wavelength of operation of antenna  40 A). 
     If care is not taken, it can be difficult to ensure that co-located antennas such as antennas  40 A and  40 B are sufficiently isolated. In some scenarios, a single conductive via is used to couple trace  126 B to positive antenna feed terminal  96 B. This conductive via extends through aligned openings in ground plane  92  and patch  104 A (e.g., openings aligned with the location of positive antenna feed terminal  96 B near the right edge of patch  104 B of  FIG. 7 ). In these scenarios, the high-magnitude electric field generated by antenna  40 A near the right edge of patch  104 A (e.g., as illustrated by curve  132 ) electromagnetically couples with the conductive via as the conductive via extends through patch  104 A. This electromagnetic cross-coupling can limit the isolation between antennas  40 A and  40 B, leading to a reduction in antenna efficiency for antennas  40 A and  40 B and/or errors in the conveyed radio-frequency signals. 
     In order to minimize coupling between the feed path for antenna  40 B and the underlying antenna  40 A, conductive via  124 B may extend through patch  104 A at a location for which the magnitude of the electric field generated by antenna  40 A is minimal (e.g., zero). As shown in  FIG. 7 , hole  130  is aligned with location X=X 1  at the center of patch  104 A. This allows conductive via  124 B to extend through patch  104 A at a location where the electric field generated by antenna  40 A has a minimum magnitude, thereby minimizing electromagnetic coupling onto the conductive via from patch  104 A. 
     Locating positive antenna feed terminal  96 B at location X=X 1  on patch  104 B may lead to an impedance mismatch between patch  104 B and transmission line  64 B. Horizontal trace  134  may allow conductive via  124 B to be coupled to patch  104 B (e.g., over conductive via  138  and positive antenna feed terminal  96 B) at a suitable location for matching the impedance of patch  104 B to the impedance of transmission line  64 B. Length  136  may be selected to ensure that patch  104 B is impedance matched to transmission line  64 B. As an example, location X=X 1  may correspond to a zero ohm impedance, location X=X 2  may correspond to an infinite impedance, and length  136  may correspond to a location at which patch  104 B exhibits a 50 ohm impedance (e.g., an impedance that matches the impedance of transmission line  64 B). In this way, antenna  40 B may be provided with suitable impedance matching (thereby maximizing antenna efficiency for antenna  40 B) without introducing undesirable electromagnetic coupling associated with passing the signal conductor for transmission line  64 B through patch  104 A. 
     In the example of  FIG. 7 , antennas  40 A and  40 B are shown as each having only a single feed for the sake of simplicity. In order to enhance the polarizations covered by antenna structures  70 , antennas  40 A and/or  40 B may be dual-polarized patch antennas that each have two corresponding feeds (e.g., as shown in  FIG. 6 , such that antenna structures  70  have a combined total of four antenna feeds), suitable geometry, and suitable phasing of ports P 1  and P 2 . 
     If desired, hole  130  and conductive via  124 B may be located within a distance ΔX from the exact center of patch  104 B (i.e., location X=X 1 ). Offsetting hole  130  from location X=X 1  may allow patch  104 A to accommodate two openings that pass two conductive vias for handling both horizontal and vertical polarizations. In general, locating the openings for both polarizations farther apart increases the isolation between polarizations for antenna  40 B. Some amount of electromagnetic coupling onto the conductive vias may be sacrificed in order to accommodate multiple polarizations with satisfactory isolation between polarizations, if desired. In other words, hole  130  may be located within a central region of patch  104 B defined by two-times distance ΔX around location X=X 1 . This central region (e.g., 2*ΔX) may be 25% of the length of patch  104 B, 20% of the length of patch  104 B, 15% of the length of patch  104 B, 10% the length of patch  104 B, or less than 10% of the length of patch  104 B, as examples. Holes  130  in patch  104 A and conductive vias  124  extending through patch  104 A may sometimes be referred to as being located at or adjacent to the center of patch  104 A when located within two times distance ΔX around location X=X 1 . 
       FIG. 8  is a top-down view (as taken in the direction of arrow  140  of  FIG. 7 ) showing how patch antennas  40 A and  40 B may each have two feeds (e.g., for covering multiple or non-linear polarizations). In the example of  FIG. 8 , dielectric substrate  120  is not shown for the sake of clarity. 
     As shown in  FIG. 8 , antenna  40 A may have a first feed that is coupled to a first transmission line  64 AV and a second feed that is coupled to a second transmission line  64 AH. The first feed may include a first ground feed terminal coupled to ground plane  92  and a first positive antenna feed terminal  96 AV coupled to patch  104 A at a first location on patch  104 A. The second antenna feed may include a second ground feed terminal coupled to ground plane  92  and a second positive antenna feed terminal  96 AH coupled to patch  104 A at a second location on patch  104 A. For example, first positive antenna feed terminal  96 AV may be located adjacent to a first side (edge)  139  of antenna structures  70  (e.g., approximately halfway across patch  104 A), whereas second positive antenna feed terminal  96 AH is located adjacent to a second side  133  of antenna structures  70  (e.g., approximately halfway across patch  104 A). 
     Antenna  40 B may have a third feed that is coupled to a third transmission line  64 BV and a fourth feed that is coupled to a fourth transmission line  64 BH. The third feed may include a third ground feed terminal coupled to ground plane  92  and a third positive antenna feed terminal  96 BV coupled to patch  104 B at a first location on patch  104 B (e.g., adjacent to side  135  of antenna structures  70  approximately halfway across patch  104 B). The fourth antenna feed may include a fourth ground feed terminal coupled to ground plane  92  and a fourth positive antenna feed terminal  96 BH coupled to patch  104 B at a second location on patch  104 B (e.g., adjacent to side  137  of antenna structures  70  approximately halfway across patch  104 B). 
     Positive antenna feed terminals  96 AH and  96 BH may handle radio-frequency signals of a first polarization (e.g., horizontally-polarized signals). Positive antenna feed terminals  96 AV and  96 BV may handle radio-frequency signals of a second polarization (e.g., vertically-polarized signals). Locating positive antenna feed terminals  96 AH and  96 BH at opposing sides of antenna structures  70  may help to maximize isolation between the horizontally-polarized signals conveyed by each positive antenna feed terminal. Similarly, locating positive antenna feed terminals  96 AV and  96 BV at opposing sides of antenna structures  70  may help to maximize isolation between the vertically-polarized signals conveyed by each positive antenna feed terminal. 
     One or more holes  130  ( FIG. 7 ) may be provided in patch  104 A to accommodate positive antenna feed terminals  96 BV and  96 BH on patch  104 B. In the example of  FIG. 8 , a first hole  130 V is formed at the center of patch  104 A for accommodating positive antenna feed terminal  96 BV and a second hole  130 H is formed at the center of patch  104 A for accommodating positive antenna feed terminal  96 BH. Transmission line  64 BV may include a first vertical conductive via  124 V extending through hole  130 V and a horizontal trace  134 V that couples first vertical conductive via  124 V to positive antenna feed terminal  96 BV over a second conductive via (e.g., a conductive via such as via  138  of  FIG. 7 ). Similarly, transmission line  64 BH may include a first vertical conductive via  124 H extending through hole  130 H and a horizontal trace  134 H that couples first vertical conductive via  124 H to positive antenna feed terminal  96 BH over a second conductive via (e.g., a conductive via such as via  138  of  FIG. 7 ). 
     Horizontal trace  134 V may have length  136 V (e.g., positive antenna feed terminal  96 BV may be offset from center  141  of patch  104 B by length  136 V). Horizontal trace  134 H may have length  136 H (e.g., positive antenna feed terminal  96 BH may be offset from center  141  by length  136 H). Lengths  136 V and  136 H may be selected to ensure that patch  104 B is impedance matched to transmission lines  64 BV and  64 BH, respectively. 
     In one suitable arrangement, conductive vias  124 V and  124 H extend through the same hole in patch  104 A (e.g., a hole located at center  141  of patch  104 A). In the example of  FIG. 8 , hole  130 V and hole  130 H are each offset from the center  141  of patch  104 A (e.g., within distance ΔX as shown in  FIG. 7  from center  141 ) to ensure that conductive via  124 V is sufficiently isolated from conductive via  124 H. By passing conductive vias  124 H and  124 V through the central region of patch  104 A (e.g., within distance ΔX as shown in  FIG. 7  from center  141 ), electromagnetic coupling onto the conductive vias from patch  104 A may be minimized or eliminated. 
     As shown in  FIG. 8 , patch  104 B has length N (e.g., a length that is approximately equal to one-half of the wavelength corresponding to a frequency between 37 GHz and 41 GHz) and patch  104 A has length M (e.g., a length that is approximately equal to one-half of the wavelength corresponding to a frequency between 27.5 GHz and 29.5 GHz). In the example of  FIG. 8 , patches  104 A and  104 B are both square patches oriented in the same direction and centered on the same point. This is merely illustrative and, in other scenarios, patches  104 A and  104 B may have other shapes or orientations. 
     If desired, each positive antenna feed terminal on patch  104 B may be fed using a conductive via that passes through locations on patch  104 A that are outside of the central region of patch  104 A (e.g., located beyond distance ΔX from center  141 ). In these scenarios, horizontal traces  134  may be omitted and antenna structures  70  may include adjustable impedance matching circuits to ensure that antennas  40 A and  40 B are sufficiently isolated. 
       FIG. 9  is a cross-sectional side view of antenna structures  70  having adjustable impedance matching circuits for ensuring that antennas  40 A and  40 B are sufficiently isolated. In the example of  FIG. 9 , dielectric layers  122  of substrate  120  are omitted for the sake of clarity. 
     As shown in  FIG. 9 , positive antenna feed terminal  96 B is located adjacent to the right edge of patch  104 B to ensure that patch  104 B is impedance matched to transmission line  64 B. Similarly, positive antenna feed terminal  96 A is located adjacent to the left edge of patch  104 A to ensures that patch  104 A is impedance matched to transmission line  64 A (e.g., positive antenna feed terminal  96 B of  FIG. 9  may be formed at the same location on patch  104 B as shown in  FIG. 7  and positive antenna feed terminal  96 A of  FIG. 9  may be formed at the same location on patch  104 A as shown in  FIG. 7 ). Positive antenna feed terminals  96 A and  96 B may cover the same polarization (e.g., positive antenna feed terminals  96 A and  96 B may form respective positive antenna feed terminals  96 AV and  96 BV or may form respective positive antenna feed terminals  96 AH and  96 BH of  FIG. 8 ). 
     A hole such as hole  156  may be formed in patch  104 A in alignment with positive antenna feed terminal  96 B on patch  104 B (e.g., outside of the central region of patch  104 A). Ground plane  92  may include an additional hole  158 B aligned with hole  156  and positive antenna feed terminal  96 B. Conductive trace  126 A in transmission line  64 A may be coupled to positive antenna feed terminal  96 A over a corresponding conductive via  154 A extending through hole  158 A in ground plane  92 . Conductive trace  126 B in transmission line  64 B may be coupled to positive antenna feed terminal  96 B over a single corresponding conductive via  154 B (e.g., without horizontal trace  134  or additional conductive vias such as conductive via  138  of  FIG. 7 ). Conductive via  154 B may extend through hole  158 B in ground plane  92  and hole  156  in patch  104 A to positive antenna feed terminal  96 B. 
     As shown in  FIG. 9 , patch  104 B is interposed between patch  104 A and first surface  164  of substrate  120 . Patch  104 A is interposed between ground plane  92  and patch  104 B. Antenna ground  92  is interposed between patch  104 A and second surface  166  of substrate  120 . An integrated circuit or chip such as integrated circuit  140  may be mounted to surface  166  of substrate  120 . Integrated circuit  140  may include radio-frequency transceiver circuitry (e.g., transceiver circuitry  28  of  FIG. 2 ), some or all of control circuitry  14  ( FIG. 2 ), or any other desired circuitry. The circuitry on integrated circuit  140  need not be formed on an integrated circuit and may be formed using other components that are mounted to substrate  120  if desired. 
     Integrated circuit  140  may include a number of ports  148  (e.g., radio-frequency input-output ports) coupled to antenna structures  70  over respective transmission lines  64 . Integrated circuit  140  may, for example, include a corresponding port  148  for each positive antenna feed terminal on antenna structures  70 . In the example of  FIG. 9 , integrated circuit  140  includes a first port  148 A coupled to positive antenna feed terminal  96 A over transmission line  64 A and a second port  148 B coupled to positive antenna feed terminal  96 B over transmission line  64 B. Integrated circuit  140  may include one or more ground ports coupled to ground plane  92 . Port  148 A may be coupled to conductive trace  126 A over conductive via  150 A. Port  148 B may be coupled to conductive trace  126 B over conductive via  150 B. 
     If care is not taken, radio-frequency signals handled by antenna  40 A may be electromagnetically coupled onto antenna  40 B and/or radio-frequency signals handled by antenna  40 B may be electromagnetically coupled onto antenna  40 A (e.g., because conductive via  154 B passes through patch  104 A at a location for which antenna  40 A exhibits a relatively high electric field magnitude). Antenna structures  70  may include impedance matching circuitry to ensure that antennas  40 A and  40 B are sufficiently isolated even though conductive via  154 B does not pass through the center of patch  104 A. 
     The impedance matching circuitry may include impedance matching circuits  162  external to integrated circuit  140  (e.g., a first impedance matching circuit  162 A and a second impedance matching circuit  162 B) and impedance matching circuits  146  within integrated circuit  140  (e.g., a third impedance matching circuit  146 A and a fourth impedance matching circuit  146 B). Impedance matching circuits  146  may be omitted if desired. 
     As shown in  FIG. 9 , impedance matching circuits  162 A and  162 B may be mounted to surface  166  of substrate  120 . Impedance matching circuit  162 A may be coupled to conductive via  154 A and thus transmission line  64 A over conductive matching via  160 A. Impedance matching circuit  162 B may be coupled to conductive via  154 B and thus transmission line  64 B over conductive matching via  160 B. Conductive matching via  160 A may be aligned with conductive via  154 A and thus positive antenna feed terminal  96 A. Conductive matching via  160 B may be aligned with conductive via  154 B and thus positive antenna feed terminal  96 B. Impedance matching circuits  162 A and  162 B may each include terminals coupled to ground  142  (e.g., grounded structures held at the same potential as ground plane  92 ). Ground  142  may include ground traces on surface  166  of substrate  120 . 
     Impedance matching circuit  146 A may be coupled between path  144 A and port  148 A. Path  144 A may be coupled to transceiver circuitry in integrated circuit  140  (e.g., transceiver circuitry  28  of  FIG. 2 ). Impedance matching circuit  146 B may be coupled to path  144 B and port  148 B. Path  144 B may be coupled to transceiver circuitry in integrated circuit  140  (e.g., transceiver circuitry  28  of  FIG. 2 ). Impedance matching circuits  146 A and  146 B may each include terminals coupled to ground  142  if desired. 
     Impedance matching circuits  162 A,  162 B,  144 A, and/or  144 B may be adjusted (e.g., by control circuitry  14  of  FIG. 2 ) to couple a selected amount of impedance to positive antenna feed terminals  96 A and  96 B based on whether positive antenna feed terminals  96 A and/or  96 B are active. The selected amount of impedance and the predetermined impedance of conductive vias  154 A,  154 B,  160 A, and  160 B may configure antenna structures  70  to exhibit sufficient isolation between antennas  40 A and  40 B. 
     For example, impedance matching circuits  162 A,  162 B,  144 A, and  144 B may be controlled using first settings when positive antenna feed terminal  96 B is active and positive antenna feed terminal  96 A is inactive, may be controlled using second settings when positive antenna feed terminal  96 B is inactive and positive antenna feed terminal  96 A is active, and may be controlled using third settings when both positive antenna feed terminals  96 A and  96 B are active (e.g., such that the antenna feeds are sufficiently isolated regardless of which feeds are active at any given time). 
     In one suitable arrangement, impedance matching circuit  162 A may be controlled to exhibit a selected impedance such that a short circuit impedance to ground  142  is coupled to positive antenna feed terminal  96 A or such that an open circuit impedance is interposed between conductive via  154 A and ground  142 . Similarly, impedance matching circuit  162 B may be controlled to exhibit a selected impedance such that a short circuit impedance to ground  142  is coupled to positive antenna feed terminal  96 B or such that an open circuit impedance is interposed between conductive via  154 B and ground  142 . This is merely illustrative and, in general, any desired fixed or variable impedance may be coupled between positive antenna feed terminals  96 A and  96 B and ground  142  using circuits  162 A and  162 B. 
     If desired, impedance matching circuit  146 A may be configured to couple any desired impedance or an adjustable impedance between port  148 A and ground  142  (e.g., when positive antenna feed terminal  96 A is inactive) or to short port  148 A to path  144 A (e.g., when positive antenna feed terminal  96 A is active). Similarly, impedance matching circuit  146 B may be configured to couple any desired impedance or an adjustable impedance between port  148 B and ground  142  (e.g., when positive antenna feed terminal  96 B is inactive) or to short port  148 B to path  144 B (e.g., when positive antenna feed terminal  96 B is active). By dynamically adjusting impedance matching circuits  162 A,  162 B,  146 A, and/or  146 B, control circuitry  14  ( FIG. 2 ) may ensure that a suitable impedance is coupled to positive antenna feed terminals  96 A and  96 B at any given time so that antenna structures  70  exhibit satisfactory isolation (e.g., regardless of which positive antenna feed terminals are active). Impedance matching circuits  162 A,  162 B,  146 A, and  146 B may sometimes be referred to herein as adjustable impedance matching circuits. 
       FIGS. 10-12  are circuit diagrams of circuitry that may be used to form impedance matching circuits  162 A,  162 B,  144 A, and/or  144 B of  FIG. 9 . As shown in  FIG. 10 , impedance matching circuit  174  may include a switch  178  coupled to ground  142 . Switch  178  may, for example, be a single-pole single-throw (SPST) switch having a first state at which an open circuit is coupled between ground  142  and terminal  176  and having a second state at which a short circuit path is coupled between ground  142  and terminal  176 . In this way, an open circuit or short circuit impedance to ground may be coupled to terminal  176 . 
     Impedance matching circuit  174  of  FIG. 10  may, for example, be used to form impedance matching circuits  162 A and/or  162 B of  FIG. 9 . Terminal  176  may be coupled to conductive matching vias  160 A or  160 B. Switch  178  may be implemented using discrete switching components that are mounted to surface  166  of substrate  120  ( FIG. 9 ) using surface mount technology (SMT) (e.g., switch  178  may be an SMT component). 
     This example of  FIG. 10  is merely illustrative and, if desired, additional components may be used so that any desired impedance is coupled between ground  142  and terminal  176  when switch  178  is open or closed. As shown in  FIG. 11 , impedance matching circuit  180  may include a switch  184  having a first switch terminal  182 , a second switch terminal  186 , and a third switch terminal  188 . An adjustable or fixed impedance circuit  190  may be coupled between switch terminal  186  and ground  142 . Impedance circuit  190  may include any desired resistive, inductive, capacitive, and/or switching components arranged in any desired manner. Control circuitry  14  ( FIG. 2 ) may provide control signals to actively adjust the impedance of impedance circuit  190  if desired. Switch terminal  188  may be coupled to ground  142 . 
     Switch  184  may have a first state in which switch terminal  182  is coupled to switch terminal  186  to couple a fixed or adjustable impedance between terminal  182  and ground  142 . Switch  184  may have a second state in which switch terminal  182  is coupled to switch terminal  188  to form a short circuit path from terminal  182  to ground  142 . Switch  184  may optionally have a third state in which an open circuit impedance is coupled to switch terminal  182 . 
     Impedance matching circuit  180  of  FIG. 11  may, for example, be used to form impedance matching circuits  162 A and/or  162 B of  FIG. 9 . In this way, control circuitry  14  ( FIG. 2 ) may control impedance matching circuit  180  to couple any desired impedance to positive antenna feed terminals  96 A and/or  96 B (e.g., to ensure that antenna  40 A is sufficiently isolated from antenna  40 B). Terminal  182  may be coupled to conductive matching vias  160 A or  160 B. Switch  184  and impedance circuit  190  may include SMT components that are mounted to surface  166  of substrate  120  ( FIG. 9 ) if desired. 
     As shown in  FIG. 12 , impedance matching circuit  192  may include a switch  201  having a first switch terminal  194 , a second switch terminal  196 , a third switch terminal  198 , and a fourth switch terminal  200 . An adjustable or fixed impedance circuit  202  may be coupled between switch terminal  200  and ground  142 . Impedance circuit  202  may include any desired resistive, inductive, capacitive, and/or switching components arranged in any desired manner. Control circuitry  14  ( FIG. 2 ) may provide control signals to actively adjust the impedance of impedance circuit  202  if desired. Switch terminal  196  may be coupled to transceiver circuitry (e.g., transceiver circuitry  28  of  FIG. 2 ) via power amplifier  204 . Switch terminal  198  may be coupled to the transceiver circuitry via low noise amplifier  206 . 
     Impedance matching circuit  192  of  FIG. 12  may, for example, be used to form impedance matching circuits  146 A and/or  146 B of  FIG. 9  (e.g., switch terminals  196  and  198  may be coupled to a corresponding path  144  of  FIG. 9 ). Control circuitry  14  ( FIG. 2 ) may control impedance matching circuit  192  to couple any desired impedance to ports  148  of integrated circuit  140  ( FIG. 9 ) or to couple ports  148  to transceiver circuitry when the corresponding positive antenna feed terminal is active. Switch  201  and impedance circuit  202  may include circuit components that are integrated within integrated circuit  140  of  FIG. 9 , for example. 
     Switch  201  may have a first state in which switch terminal  194  is coupled to switch terminal  200  to couple a fixed or adjustable impedance between switch terminal  194  and ground  142  (e.g., to the corresponding port  148  of integrated circuit  140  of  FIG. 9 ). Switch  201  may have a second state in which switch terminal  194  is coupled to switch terminal  198  so that radio-frequency signals received by the corresponding positive antenna feed terminal are passed to the transceiver circuitry via low noise amplifier  206 . Switch  201  may have a third state in which switch terminal  194  is coupled to switch terminal  196  so that radio-frequency signals transmitted by the transceiver circuitry are conveyed to the corresponding positive antenna feed terminal via power amplifier  204 . 
     In one suitable arrangement, switch  201  may couple switch terminal  194  to switch terminal  200  when the positive antenna feed terminal coupled to switch terminal  194  is inactive. This may adjust the impedance of the port  148  coupled to switch terminal  194  to ensure that the antennas operate with satisfactory isolation and antenna efficiency. Switch  201  may couple switch terminal  194  to one of switch terminals  196  and  198  when the positive antenna feed terminal  96  coupled to switch terminal  194  is active. 
       FIG. 13  is a graph of isolation (S 21 ) for antennas  40 A and  40 B. For example, curve  208  corresponds to scenarios where antenna  40 B is coupled to transmission line  64 B over a single conductive via without impedance matching circuits  162 A,  162 B,  146 A, or  146 B. In this scenario, the relatively high magnitude electric field near the edge of patch  104 A may cross-couple with the conductive via as the conductive via passes through patch  104 A, resulting in a relatively low isolation at desired frequencies (e.g., frequencies including a first frequency F 1  in a first communications band such as a communications band from 27.5 GHz to 29.5 GHz and a second frequency F 2  in a second communications band such as a communications band from 37 GHz to 41 GHz). Such low isolation may reduce the overall antenna efficiency for antenna structures  70  and generate errors in the conveyed wireless data. 
     Curve  210  corresponds to antenna structures  70  of the types shown in  FIGS. 7-9 . Forming impedance matching circuits  162 A,  162 B,  146 A, and/or  146 B of  FIG. 9  may allow active adjustment of the feed impedance for antennas  40 A and  40 B to achieve a relatively high level of isolation. Similarly, passing conductive via  124 B of  FIG. 7  through the central region of patch  104 A may minimize the amount of coupling between patch  104 A and the feed path for antenna  40 B, thereby allowing antennas  40 A and  40 B to achieve a relatively high level of isolation. In this way, antennas  40 A and  40 B may be co-located within device  10  (thereby minimizing space consumption) while also exhibiting satisfactory isolation and thus antenna performance within multiple communications bands above 10 GHz. 
     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: 20180716
Publication Date: 20200728
Grant Date: 20200728
Priority Date: 20180716
Inventors: RAJAGOPALAN, HARISH
EDWARDS, JENNIFER M.
PAULOTTO, Simone
AVSER, BILGEHAN
XU, HAO
GOMEZ ANGULO, RODNEY A.
BARBIERI, TRAVIS A.
ATMATZAKIS, GEORGIOS
MOW, MATTHEW A.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0414", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0414", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/328", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2291", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/045", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/045", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/523", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0414", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/523", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/045", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 69138537