Antenna Structures and Electrical Components with Grounding

BACKGROUND

0001This relates generally to electronic devices, and, more particularly, to grounding structures for antennas and components in electronic devices.

0002Electronic devices such as portable computers and handheld electronic devices are often provided with wireless communications capabilities. For example, electronic devices may use long-range wireless communications circuitry to communicate using cellular telephone bands. Electronic devices may use short-range wireless communications links to handle communications with nearby equipment. Electronic devices are also often provided with microphones, cameras, and other electronic components.

0003It can be difficult to incorporate antennas and electrical components successfully into an electronic device. Some electronic devices are manufactured with small form factors, so space is limited. In many electronic devices, the presence of conductive structures associated with components can influence the performance of antennas. There is also a potential for antenna disruptions from electromagnetic interference when antennas and electrical components are mounted in close proximity with insufficient grounding. This further restricts potential mounting arrangements for components and antennas.

0004It would therefore be desirable to be able to provide improved grounding arrangements for electronic devices with antennas and electronic components.

SUMMARY

0005An electronic device may have a conductive housing with an antenna window. A display module may be mounted within the conductive housing. A display cover layer may cover the display module. The inner surface of an inactive edge region of the display cover layer may be coated with a layer of opaque masking material. Antenna structures may be mounted adjacent to the antenna window under the layer of opaque masking material on the display cover layer.

0006The antenna structures may be formed from patterned metal traces on a dielectric carrier. The patterned metal traces may form an antenna resonating element with positive and ground feed terminals.

0007A flexible printed circuit may include a transmission line with positive and ground conductors respectively coupled to the positive and ground feed terminals. A proximity sensor may be formed from capacitive electrodes within the flexible printed circuit.

0008The flexible printed circuit may have a tail that contains the transmission line. The positive conductor in the transmission line may be maintained at a desired distance from the conductive housing a polymer sheet. Conductive structures such as screws and vias and other metal structures in the flexible printed circuit may be used to short the ground conductor in the transmission line to the conductive housing.

0009A portion of the antenna structures may protrude between a microphone and a camera module. The microphone may be mounted to a microphone flexible printed circuit. The camera module may be mounted to a camera flexible printed circuit. The conductive housing may have a vertical shielding wall that is adjacent to the antenna structures. The microphone flexible printed circuit and the camera flexible printed circuit may pass through the opening.

0010The camera module may have plastic camera module housing structures. An inner surface of the plastic camera module housing structures may be coated with a layer of metal that serves as an electromagnetic signal interference shield. A U-shaped conductive fabric layer may be used as a grounding structure. The conductive fabric layer may be interposed between the camera flexible printed circuit and the microphone flexible printed circuit adjacent to the opening in the vertical shielding wall.

0011Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

0012<figref idref="DRAWINGS">FIG. 1</figref> is a front perspective view of an illustrative electronic device of the type that may be provided with grounding structures for antennas and components in accordance with an embodiment of the present invention.

0013<figref idref="DRAWINGS">FIG. 2</figref> is a diagram showing circuitry that may be used to operate antenna structures and proximity sensor structures in accordance with an embodiment of the present invention.

0014<figref idref="DRAWINGS">FIG. 3</figref> is a top view of an end portion of an electronic device housing containing two antennas in accordance with an embodiment of the present invention.

0015<figref idref="DRAWINGS">FIG. 4</figref> is a cross-sectional side view of a portion of an electronic device taken through a microphone and camera module with grounding structures in accordance with an embodiment of the present invention.

0016<figref idref="DRAWINGS">FIG. 5</figref> is a cross-sectional side view of a portion of a camera module and associated flexible printed circuit structures in accordance with an embodiment of the present invention.

0017<figref idref="DRAWINGS">FIG. 6</figref> is a cross-sectional side view of a portion of an electronic device showing how a U-shaped conductive fabric gasket may be used in shorting together adjacent flexible printed circuits as part of a grounding arrangement in accordance with an embodiment of the present invention.

0018<figref idref="DRAWINGS">FIG. 7</figref> is a perspective view of an illustrative grounding structure of the type that may be used in an electronic device in accordance with an embodiment of the present invention.

0019<figref idref="DRAWINGS">FIG. 8</figref> is a top view of an illustrative antenna having a carrier that is used in forming an antenna support and a support for a proximity sensor flexible printed circuit in accordance with an embodiment of the present invention.

0020<figref idref="DRAWINGS">FIG. 9</figref> is a perspective view of a portion of an electronic device having an antenna with a grounded transmission line in accordance with an embodiment of the present invention.

0021<figref idref="DRAWINGS">FIG. 10</figref> is a cross-sectional side view of a transmission line for an antenna having grounding structures in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

0022Electronic devices may be provided with antennas and electronic components such as microphones, cameras, sensors, and other electronic components. It may be desirable to mount components on flexible structures. For example, it may be desirable to mount a microphone, a camera, and other electronic components on flexible printed circuit structures. Flexible printed circuits, which are sometimes referred to as flex circuits, may include patterned metal traces on flexible substrates such as layers of polyimide or other flexible polymer sheets. Flexible printed circuits may be used in forming antennas, capacitive sensors (e.g., electrodes for a proximity sensor), assemblies that include antenna and capacitive sensor structures, other electronic device components, or combinations of these structures.

0023An illustrative electronic device in which electronic components and antenna structures may be used is shown in <figref idref="DRAWINGS">FIG. 1</figref>. Device <b>10</b> may include one or more antenna resonating elements, one or more capacitive proximity sensor structures, one or more components that include antenna structures and proximity sensor structures, microphone structures, camera structures, and other electronic components. In the illustrative configuration of <figref idref="DRAWINGS">FIG. 1</figref>, device <b>10</b> has the shape of a portable device such as a cellular telephone or other handheld device, tablet computer, or other portable equipment. In general, electronic devices <b>10</b> may be desktop computers, computers integrated into computer monitors, portable computers, tablet computers, handheld devices, cellular telephones, wristwatch devices, pendant devices, other small or miniature devices, televisions, set-top boxes, or other electronic equipment.

0024As shown in <figref idref="DRAWINGS">FIG. 1</figref>, device <b>10</b> may have a display such as display <b>50</b>. Display <b>50</b> may be mounted on a front (top) surface of device <b>10</b> or may be mounted elsewhere in device <b>10</b>. Device <b>10</b> may have a housing such as housing <b>12</b>. Housing <b>12</b> may have curved portions that form the edges of device <b>10</b> and a relatively planar portion that forms the rear surface of device <b>10</b> (as an example). Housing <b>12</b> may also have other shapes, if desired.

0025Housing <b>12</b> may be formed from conductive materials such as metal (e.g., aluminum, stainless steel, etc.), carbon-fiber composite material or other fiber-based composites, glass, ceramic, plastic, other materials, or combinations of these materials. A radio-frequency (RF) window (sometimes referred to as an antenna window) such as antenna window <b>58</b> may be formed in housing <b>12</b> (e.g., in a configuration in which the rest of housing <b>12</b> is formed from conductive structures). Window <b>58</b> may be formed from plastic, glass, ceramic, or other dielectric. Antenna and proximity sensor structures for device <b>10</b> may be formed in the vicinity of window <b>58</b>, may be covered with dielectric portions of housing <b>12</b>, and/or may be mounted under dielectric structures such as portions of a display cover layer or other dielectric display structure.

0026Device <b>10</b> may have user input-output devices such as button <b>59</b>. Display <b>50</b> may be a touch screen display that is used in gathering user touch input. The surface of display <b>50</b> may be covered using a dielectric member such as a planar cover glass member or a clear layer of plastic or the outermost layer of display <b>50</b> may be formed from a portion of a color filter layer or other display layer. The central portion of display <b>50</b> (shown as region <b>56</b> in <figref idref="DRAWINGS">FIG. 1</figref>) may be an active region that contains an array of display pixels for displaying images and that is sensitive to touch input. The peripheral portion of display <b>50</b> such as region <b>54</b> may be an inactive region that is free from touch sensor electrodes and display pixels and that does not display images.

0027A layer of opaque masking material such as opaque ink or plastic may be placed on the underside of display <b>50</b> in peripheral region <b>54</b> (e.g., on the underside of the cover glass). This layer may be transparent to radio-frequency signals. The conductive touch sensor electrodes in region <b>56</b> and the conductive structures associated with the array of display pixels in region <b>56</b> may tend to block radio-frequency signals. However, radio-frequency signals may pass through the cover glass and the opaque masking layer in inactive display region <b>54</b> (as an example). Radio-frequency signals may also pass through antenna window <b>58</b> or dielectric housing walls in housing formed from dielectric material. Lower-frequency electromagnetic fields may also pass through dielectric structures such as portions of a display cover layer, window <b>58</b>, or other dielectric housing structures, so capacitance measurements for a proximity sensor may be made through these dielectric structures.

0028With one suitable arrangement, housing <b>12</b> may be formed from a metal such as aluminum. Portions of housing <b>12</b> in the vicinity of antenna window <b>58</b> may be used as antenna ground. Antenna window <b>58</b> may be formed from a dielectric material such as polycarbonate (PC), acrylonitrile butadiene styrene (ABS), a PC/ABS blend, or other plastics (as examples). Window <b>58</b> may be attached to housing <b>12</b> using adhesive, fasteners, or other suitable attachment mechanisms. To ensure that device <b>10</b> has an attractive appearance, it may be desirable to form window <b>58</b> so that the exterior surfaces of window <b>58</b> conform to the edge profile exhibited by housing <b>12</b> in other portions of device <b>10</b>. For example, if housing <b>12</b> has straight edges <b>12</b>A and a flat bottom surface, window <b>58</b> may be formed with a right-angle bend and vertical sidewalls. If housing <b>12</b> has curved edges <b>12</b>A, window <b>58</b> may have a similarly curved exterior surface along the edge of device <b>10</b>.

0029A schematic diagram of an illustrative configuration that may be used for electronic device <b>10</b> is shown in <figref idref="DRAWINGS">FIG. 2</figref>. As shown in <figref idref="DRAWINGS">FIG. 2</figref>, electronic device <b>10</b> may include control circuitry <b>29</b>. Control circuitry <b>29</b> may include storage and processing circuitry for controlling the operation of device <b>10</b>. Control circuitry <b>29</b> may, for example, 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. Control circuitry <b>29</b> may include processing circuitry based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc.

0030Control circuitry <b>29</b> may be used to run software on device <b>10</b>, such as operating system software and application software. Using this software, control circuitry <b>29</b> may, for example, transmit and receive wireless data, tune antennas to cover communications bands of interest, process proximity sensor signals, adjust radio-frequency transmit powers based on proximity sensor data, and perform other functions related to the operation of device <b>10</b>.

0031Input-output devices <b>30</b> may be used to allow data to be supplied to device <b>10</b> and to allow data to be provided from device <b>10</b> to external devices. Input-output circuitry <b>30</b> may include communications circuitry such as wired communications circuitry. Device <b>10</b> may also use wireless circuitry such as radio-frequency transceiver circuitry <b>206</b> and antenna structures <b>204</b> to communicate over one or more wireless communications bands.

0032Input-output devices <b>30</b> may also include input-output components with which a user can control the operation of device <b>10</b>. A user may, for example, supply commands through input-output devices <b>30</b> and may receive status information and other output from device <b>10</b> using the output resources of input-output devices <b>30</b>.

0033Input-output devices <b>30</b> may include sensors and status indicators such as an ambient light sensor, a proximity sensor, a temperature sensor, a pressure sensor, a magnetic sensor, an accelerometer, and light-emitting diodes and other components for gathering information about the environment in which device <b>10</b> is operating and providing information to a user of device <b>10</b> about the status of device <b>10</b>. Audio components in devices <b>30</b> may include speakers and tone generators for presenting sound to a user of device <b>10</b> and microphones for gathering user audio input. Devices <b>30</b> may include one or more displays such as display <b>50</b>. Displays may be used to present images for a user such as text, video, and still images. Sensors in devices <b>30</b> may include a touch sensor array that is formed as one of the layers in display <b>50</b>. During operation, user input may be gathered using buttons and other input-output components in devices <b>30</b> such as touch pad sensors, buttons, joysticks, click wheels, scrolling wheels, touch sensors such as a touch sensor array in a touch screen display or a touch pad, key pads, keyboards, vibrators, cameras, and other input-output components.

0034Device <b>10</b> may include wireless communications circuitry such as radio-frequency transceiver circuitry <b>206</b>, power amplifier circuitry, low-noise input amplifiers, passive radio frequency components, one or more antennas such as antenna structures <b>204</b>, and other circuitry for handling radio frequency wireless signals. The wireless communications circuitry may include radio-frequency transceiver circuits for handling multiple radio-frequency communications bands. For example, wireless communications circuitry in device <b>10</b> may include transceiver circuitry <b>206</b> for handling cellular telephone communications, wireless local area network signals, and satellite navigation system signals such as signals at 1575 MHz from satellites associated with the Global Positioning System. Transceiver circuitry <b>206</b> 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 <b>206</b> may use cellular telephone transceiver circuitry for handling wireless communications in cellular telephone bands such as the bands in the range of 700 MHz to 2.7 GHz (as examples).

0035The wireless communications circuitry in device <b>10</b> can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry in device <b>10</b> may include wireless circuitry for receiving radio and television signals, paging circuits, etc. 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. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles.

0036Antenna structures <b>204</b> may include one or more antennas. Antenna structures <b>204</b> may include inverted-F antennas, patch antennas, loop antennas, monopoles, dipoles, single-band antennas, dual-band antennas, antennas that cover more than two bands, or other suitable antennas. As an example, device <b>10</b> may include one or more antennas such as dual band inverted-F antennas formed from metal structures supported by a dielectric carrier.

0037To provide antenna structures <b>204</b> with the ability to cover communications frequencies of interest, antenna structures <b>204</b> may be provided with tunable circuitry <b>208</b>. Tunable circuitry <b>208</b> may be controlled by control signals from control circuitry <b>29</b>. For example, control circuitry <b>29</b> may supply control signals to tunable circuitry <b>208</b> using control path <b>210</b> whenever it is desired to tune antenna structures <b>204</b> to cover a desired communications band during operation of device <b>10</b>. Path <b>222</b> may be used to convey data between control circuitry <b>29</b> and radio-frequency transceiver circuitry <b>206</b> (e.g., when transmitting wireless data or when receiving and processing wireless data).

0038Transceiver circuitry <b>206</b> may be coupled to antenna structures <b>204</b> by signal paths such as signal path <b>212</b>. Signal path <b>212</b> may include one or more transmission lines. As an example, signal path <b>212</b> of <figref idref="DRAWINGS">FIG. 2</figref> may be a transmission line having a positive signal conductor such as line <b>214</b> and a ground signal conductor such as line <b>216</b>. Lines <b>214</b> and <b>216</b> may form parts of a coaxial cable, parts of a microstrip transmission line, or parts of other transmission line structures. The impedance of transmission line <b>212</b> may be 50 ohms (as an example). A matching network formed from components such as inductors, resistors, and capacitors may be used in matching the impedance of antenna structures <b>204</b> to the impedance of transmission line <b>212</b>. Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc.

0039Transmission line <b>212</b> may be coupled to antenna feed structures associated with antenna structures <b>204</b>. As an example, antenna structures <b>204</b> may include an inverted-F antenna having an antenna feed with a positive antenna feed terminal such as terminal <b>218</b> and a ground antenna feed terminal such as ground antenna feed terminal <b>220</b>. Positive transmission line conductor <b>214</b> may be coupled to positive antenna feed terminal <b>218</b> and ground transmission line conductor <b>216</b> may be coupled to ground antenna feed terminal <b>220</b>. Other types of antenna feed arrangements may be used if desired. The illustrative feeding configuration of <figref idref="DRAWINGS">FIG. 2</figref> is merely illustrative.

0040Filter circuitry such as direct current (DC) blocking capacitors <b>224</b> may, if desired, be interposed within paths <b>214</b> and <b>216</b>. Capacitors <b>224</b> may help prevent signals at low frequencies (e.g., frequencies below the lowest frequencies used by antenna structures <b>204</b> in transmitting and receiving wireless data) from reaching transceiver circuitry <b>206</b> and potentially interfering with the operation of radio-frequency transceiver circuitry <b>206</b>.

0041Tunable circuitry <b>208</b> may be formed from one or more tunable circuits such as circuits based on capacitors, resistors, inductors, and switches. Tunable circuitry <b>208</b> may be implemented using discrete components mounted to a substrate such as a rigid printed circuit board (e.g., a printed circuit board formed from glass-filled epoxy), a flexible printed circuit formed from a sheet of polyimide or a layer of other flexible polymer, a plastic carrier, a glass carrier, a ceramic carrier, or other dielectric support. With one suitable arrangement, tunable circuitry <b>208</b> may include an inductor-based tunable component (e.g., a component having one or more inductors in parallel and a switch that can be configured to selectively switch one or more of the inductors into use). An inductor-based tunable component of this type (e.g., a switchable inductor component) may be coupled between one or more of the arms in a dual arm inverted-F antenna and a ground plane or may otherwise be used in tuning the performance of antenna structures <b>204</b>.

0042As shown in <figref idref="DRAWINGS">FIG. 2</figref>, device <b>10</b> may include a proximity sensor that includes proximity sensor electrode structures <b>226</b>. Proximity sensor electrode structures <b>226</b> may include one or more or two or more layers of metal electrodes for sensing capacitance changes in the surroundings of device <b>10</b>. If desired, proximity sensor electrode structures <b>226</b> may be formed from metal traces on a flexible printed circuit or other dielectric carrier. The flexible printed circuit may be mounted within device <b>10</b> so as to surround or at least partly overlap antenna structures <b>204</b>, as shown in <figref idref="DRAWINGS">FIG. 2</figref>. With this type of arrangement, proximity sensor electrode structures <b>226</b> and antenna structures <b>204</b> may experience similar environments. This allows the proximity sensor to monitor the vicinity of antenna structures <b>204</b> for external objects such as part of a user's body. Proximity sensor signals that indicate that the user's body is present in the vicinity of antenna structures <b>204</b> may then be used to limit transmitted radio-frequency signal power from radio-frequency transceiver circuitry <b>206</b> to ensure that device <b>10</b> satisfies regulatory limits on transmitted wireless signal powers.

0043Proximity sensor circuitry <b>230</b> may be coupled to proximity sensor electrode <b>226</b> by path <b>228</b>. Inductors <b>229</b> or other filter circuitry for blocking high-frequency signals may be interposed in path <b>228</b>. The presence of high-frequency signal blocking circuitry in path <b>228</b> may help prevent radio-frequency antenna signals that are associated with antenna structures <b>204</b> from being conveyed to proximity sensor circuitry <b>230</b>. Proximity sensor circuitry <b>228</b> can receive proximity sensor signals (e.g., lower frequency signals) from electrode structures <b>226</b> through inductors <b>229</b> and can determine whether or not external objects are present in the vicinity of structures <b>226</b> based on these proximity sensor signals. For example, if a user places a body part in the vicinity of proximity sensor electrode <b>226</b>, the capacitance of sensor electrode <b>226</b> may vary and, by monitoring these capacitance fluctuations, circuitry <b>230</b> can detect the presence of the body part.

0044<figref idref="DRAWINGS">FIG. 3</figref> is a top view of an end portion of device <b>10</b> of <figref idref="DRAWINGS">FIG. 1</figref>. In the illustrative configuration of <figref idref="DRAWINGS">FIG. 3</figref>, device <b>10</b> includes at least two antennas such as first antenna <b>204</b>A and second antenna <b>204</b>B. Antennas <b>204</b>A and <b>204</b>B may be, for example, inverted-F antennas that are used in handling cellular telephone communications. This is, however, merely illustrative. Antennas <b>204</b>A and <b>204</b>B may, in general, be configured to handle communications in any communications bands of interest and may use any suitable type of antenna resonating element structure. Additional antennas may be included in device <b>10</b>, if desired. For example, wireless local area network antennas may be located at an opposing end of device <b>10</b>.

0045In a configuration of the type shown in <figref idref="DRAWINGS">FIG. 3</figref> in which there are at least two antennas in device <b>10</b>, the two antennas may be used as part of a multiple input multiple output (MIMO) antenna scheme or may be used as part of an antenna diversity arrangement in which control circuitry <b>29</b> (<figref idref="DRAWINGS">FIG. 2</figref>) switches one of the two antennas into use in real time depending on signal quality criteria or other suitable switching criteria. Antennas in device <b>10</b> may be fixed and/or tunable. For example, antenna <b>204</b>B may be a fixed primary antenna that is used for transmitting and receiving wireless signals, whereas antenna <b>204</b>A may be a tunable secondary antenna that is used exclusively or primarily for receiving wireless signals.

0046Proximity sensor structures such as proximity sensor electrode structures <b>226</b> of <figref idref="DRAWINGS">FIG. 2</figref> may be implemented using a flexible printed circuit such as flexible printed circuit <b>242</b>. Flexible printed circuit <b>242</b> may include metal traces for implementing transmission line <b>212</b> of <figref idref="DRAWINGS">FIG. 2</figref>, traces for mounting components such as filter capacitors <b>224</b> and filter inductors <b>229</b>, metal structures for coupling transmission line <b>212</b> to antenna terminals <b>218</b> and <b>220</b> of <figref idref="DRAWINGS">FIG. 2</figref>, and other conductive structures. Conductive metal traces or other conductive structures for forming antenna structures <b>204</b>B may be formed on the surface of a dielectric carrier or on a printed circuit. In a configuration in which patterned metal antenna traces are formed on the surface of a carrier, the carrier may, for example, be a plastic carrier having a protruding portion such as portion <b>232</b> of <figref idref="DRAWINGS">FIG. 3</figref>.

0047Tail portions <b>244</b> and <b>246</b> of flexible printed circuit <b>242</b> may extend over housing structures such as housing wall structures <b>12</b>W of housing <b>12</b>. The presence of tail portions <b>244</b> and <b>246</b> helps accommodate movement of antenna structures coupled to flexible printed circuit <b>242</b> relative to housing <b>12</b>. Housing wall structures <b>12</b>W may be a metal wall that extends vertically (out of the page in the orientation of <figref idref="DRAWINGS">FIG. 3</figref>) from the rear surface of housing <b>12</b>. Housing wall structures <b>12</b>W may be interposed between antenna structures <b>204</b>A and <b>204</b>B and device circuitry located in interior portion <b>292</b> of device <b>10</b> and may therefore serve as a part of an electromagnetic interference shield.

0048Device <b>10</b> may include components such as microphone <b>234</b> and camera <b>236</b>. In region <b>250</b>, microphone <b>234</b> may be mounted on a flexible printed circuit (sometimes referred to as a microphone flexible printed circuit) and camera <b>236</b> may be mounted on a flexible printed circuit (sometimes referred to as a camera flexible printed circuit). The microphone and camera flexible printed circuits may run along the inner surface of antenna window <b>58</b> and through an opening in portion <b>248</b> of inner housing wall <b>12</b>W (e.g., a mousehole opening).

0049A cross-sectional side view of microphone <b>234</b> and camera <b>236</b> in device <b>10</b> taken along line <b>238</b> and viewed in direction <b>240</b> is shown in <figref idref="DRAWINGS">FIG. 4</figref>. As shown in <figref idref="DRAWINGS">FIG. 4</figref>, device <b>10</b> may have a display cover layer such as display cover layer <b>254</b>. Display module <b>252</b> may be mounted in active region <b>56</b> of display <b>50</b> for producing images for user of device <b>10</b>. In inactive region <b>54</b>, a layer of opaque masking material such as opaque masking layer <b>258</b> may be formed on the underside of display cover layer <b>254</b> to hide internal components from view. Camera <b>236</b> (sometimes referred to as a camera module) may be mounted under opening <b>274</b> in opaque masking layer <b>258</b> using mounting structures such as mounting ring <b>276</b>. During operation of camera <b>236</b>, image light <b>272</b> may be received through opening <b>274</b>. Optical structures such as lenses <b>270</b> may focus incoming light <b>272</b> onto digital image sensor <b>268</b> (e.g., a digital imaging sensor implemented on an integrated circuit).

0050Camera module <b>236</b> may be provided with camera housing walls such as walls <b>264</b>. Housing structures such as walls <b>264</b> may be formed from one or more structures. For example, housing walls <b>264</b> may be formed from molded and/or machined plastic parts. To help electrically isolate internal portions of camera <b>236</b> such as image sensor <b>268</b> from antenna structures in device <b>10</b> such as antenna structures <b>204</b> of <figref idref="DRAWINGS">FIG. 4</figref>, camera module <b>236</b> may be provided with shielding structures. The shielding structures may be formed form a metal coating on the inside or outside surfaces of camera module <b>236</b>.

0051As an example, metal coating <b>266</b> may be formed on the inner surfaces of plastic walls <b>264</b> of camera module <b>264</b>. Metal coating <b>266</b> may be formed by physical vapor deposition techniques, electroplating, or other suitable fabrication techniques. Portions <b>278</b> of metal coating layer <b>266</b> may be formed on the lower surfaces of camera module housing <b>264</b> and may be electrically coupled to a substrate such as camera flexible printed circuit <b>262</b>. For example, solder, conductive adhesive, conductive tape, conductive foam, or other conductive materials may be used to short metal layer <b>266</b> of camera module <b>236</b> to ground path metal traces on camera flexible printed circuit <b>262</b>.

0052Microphone <b>234</b> may be mounted on microphone flexible printed circuit <b>260</b>. Signal lines on flexible printed circuit <b>260</b> may be used to gather microphone signals from microphone <b>234</b>. Microphone <b>234</b> may receive sound through opening <b>290</b> in antenna window <b>58</b> or other portions of the housing for device <b>10</b>. Antenna window <b>58</b> may have a curved cross-sectional shape of the type shown in <figref idref="DRAWINGS">FIG. 4</figref> and may form part of the housing of device <b>10</b>.

0053Microphone flexible printed circuit <b>260</b> and camera flexible printed circuit <b>262</b> may extend through an opening such as opening <b>280</b> in housing wall <b>12</b>W (e.g., an opening in region <b>248</b> of wall <b>12</b>W of <figref idref="DRAWINGS">FIG. 3</figref>). Housing <b>12</b> and housing wall <b>12</b>W may be formed from a metal such as aluminum and may serve as a ground for circuitry and components in device <b>10</b>. If desired, housing wall <b>12</b>W may be a machined feature that is an integral portion of the machined metal structures used to form housing <b>12</b>.

0054To help ground structures in device <b>10</b> and thereby allow antenna structures <b>204</b>B to function satisfactorily, the structures of <figref idref="DRAWINGS">FIG. 4</figref> such as camera <b>236</b>, camera flexible printed circuit <b>262</b>, microphone <b>234</b>, and microphone flexible printed circuit <b>260</b> may be grounded to housing <b>12</b> or other suitable ground structures. Grounding structures <b>282</b> may, for example, be used to ground camera flexible printed circuit <b>262</b> to microphone flexible printed circuit <b>260</b>.

0055Grounding structures <b>282</b> may be formed from a conductive material such as a conductive fabric. Microphone flexible printed circuit <b>260</b> may be grounded to housing <b>12</b> directly or through intervening structures such as audio jack flexible printed circuit <b>280</b>. The presence of grounding structures <b>282</b> such as end portion <b>294</b> of grounding structures <b>282</b> may help reduce electromagnetic interference by helping to prevent antenna signals from antenna <b>204</b>B from entering interior portion <b>292</b> of device <b>10</b> through opening <b>280</b> and by helping to prevent interference signals from interior <b>292</b> from reaching antenna <b>204</b>B through opening <b>280</b>. In effect, portion <b>294</b> of grounding structures <b>282</b> helps seal opening <b>280</b> in metal shielding wall <b>12</b>W.

0056<figref idref="DRAWINGS">FIG. 5</figref> is a cross-sectional side view of a portion of camera <b>236</b> and associated flexible printed circuit structures such as camera flexible printed circuit <b>262</b> and microphone flexible printed circuit <b>260</b>. As shown in <figref idref="DRAWINGS">FIG. 5</figref>, metal portions <b>278</b> of metal shielding coating <b>266</b> on camera module housing structures <b>264</b> may be shorted to metal traces <b>306</b> in camera flexible printed circuit <b>262</b> using conductive adhesive <b>308</b>. Metal traces <b>306</b> may be, for example, ground traces in camera flexible printed circuit <b>262</b>.

0057A biasing structure such as conductive foam <b>300</b> may be used to press camera module <b>236</b> upwards towards display cover layer <b>254</b> while compressing structures such as camera flexible printed circuit <b>262</b> and microphone flexible printed circuit <b>260</b> downwards against antenna window <b>58</b>. Conductive structures such as a sheet of stainless steel or other stiffener <b>302</b> may be provided between metal ground traces such a traces <b>312</b> in camera flexible printed circuit <b>262</b> and conductive foam <b>300</b>. Stiffener <b>302</b> may provide localized structural support for flexible printed circuit <b>260</b>. Traces <b>312</b> may be shorted to traces <b>306</b> (e.g., using vias or other paths), so that traces <b>312</b> serve as ground traces. Metal traces <b>304</b> on microphone printed circuit <b>260</b> may be shorted to the ground traces on camera flexible printed circuit <b>262</b> and therefore to shield <b>266</b> in camera module <b>236</b> through conductive foam <b>300</b>. If desired, conductive adhesive may be interposed between stiffener <b>302</b> and traces <b>312</b> and/or between stiffener <b>302</b> and conductive foam <b>300</b>. Conductive adhesive may optionally also be interposed between traces <b>304</b> and conductive foam <b>300</b>.

0058<figref idref="DRAWINGS">FIG. 6</figref> is a cross-sectional side view of grounding structures <b>282</b> and associated structures in the vicinity of internal housing wall <b>12</b>W. As shown in <figref idref="DRAWINGS">FIG. 6</figref>, grounding structures <b>282</b> may have a U-shaped cross section. U-shaped grounding structures <b>282</b> may be formed from a sheet of conductive fabric that is bent around bend axis <b>330</b>. If desired, other shapes such as tube shapes, corrugated shapes formed from an undulating fabric sheet, or other configurations may be used for grounding structures <b>282</b>.

0059Conductive fabric for grounding structures <b>282</b> may be formed from metal fibers, plastic fibers coated with metal, a combination of metal and plastic fibers, or other suitable conductive fibers. Camera flexible printed circuit <b>262</b> may have ground traces that are shorted to grounding structures <b>282</b> using conductive adhesive <b>320</b>. Conductive adhesive <b>322</b> may be used to attach grounding structure <b>282</b> to ground conductive ground traces in microphone flexible printed circuit <b>260</b>. Conductive adhesive <b>324</b> may be used to short the ground traces of microphone flexible printed circuit <b>260</b> to metal ground traces in a printed circuit such as audio jack flexible printed circuit <b>280</b>. Conductive adhesive <b>326</b> may be interposed between audio jack flexible printed circuit <b>280</b> and the inner surface of metal housing <b>12</b>. Metal housing <b>12</b> may serve as ground. If desired, one or more of the conductive adhesive layers of <figref idref="DRAWINGS">FIG. 6</figref> may be omitted and/or other conductive structures (e.g., solder, conductive fabric, conductive metal tape, welds, fasteners, metal paint, etc.) may be used in electrically coupling and thereby grounding the layers of <figref idref="DRAWINGS">FIG. 6</figref>.

0060<figref idref="DRAWINGS">FIG. 7</figref> is a perspective view of grounding structures <b>282</b> in an illustrative U-shaped configuration. As shown in <figref idref="DRAWINGS">FIG. 7</figref>, grounding structures <b>282</b> may be formed from a conductive fabric having conductive fibers such as fibers <b>332</b>. Structure <b>282</b> may be formed from a bent sheet of conductive fabric or conductive fabric having other suitable shapes. Openings <b>334</b> may be formed in structure <b>282</b> along bend axis <b>330</b> to facilitate bending of structure <b>282</b> around bend axis <b>330</b>. If desired, a tube or a structure with other shapes may be formed from conductive fabric having fibers <b>332</b>. The U-shaped structure of <figref idref="DRAWINGS">FIG. 7</figref> is merely illustrative.

0061<figref idref="DRAWINGS">FIG. 8</figref> is a top view of antenna structures <b>204</b>B. In the illustrative configuration of <figref idref="DRAWINGS">FIG. 8</figref>, antenna structures <b>204</b>B have a dielectric carrier such as carrier <b>336</b>. Carrier <b>336</b> may be formed from plastic, glass, ceramic, printed circuit board material, or other suitable dielectric material. Patterned conductive antenna resonating element traces <b>338</b> may be formed on the surface of dielectric carrier <b>336</b> (e.g., using selective surface activation and electroplating such as used in laser direct structuring techniques). Antenna feed terminals <b>218</b> and <b>220</b> may be formed from pad-shaped structures or other structures in the patterned metal coating on carrier <b>336</b>.

0062Proximity sensor electrode structures <b>226</b> may be formed from metal traces within flexible printed circuit <b>340</b>. Tail portion <b>342</b> of flexible printed circuit <b>340</b> may contain transmission line <b>212</b> of <figref idref="DRAWINGS">FIG. 2</figref>. Vias and hot bar solder connections may be used to couple transmission line positive conductor <b>214</b> to terminal <b>218</b> in the metal traces on the surface of carrier <b>336</b> and to couple transmission line ground conductor <b>216</b> to terminal <b>220</b> in the metal traces on the surface of carrier <b>336</b>. Patterned metal traces <b>338</b> may cover some or all of the surfaces of carrier <b>336</b> to form an inverted-F antenna resonating element or an antenna resonating element of another suitable type.

0063A perspective view of antenna structures <b>204</b>B mounted in device <b>10</b> is shown in <figref idref="DRAWINGS">FIG. 9</figref>. As shown in <figref idref="DRAWINGS">FIG. 9</figref>, foam such as foam <b>366</b> may be used to bias antenna structures <b>204</b>B upwards towards display cover layer <b>254</b> (<figref idref="DRAWINGS">FIG. 4</figref>). The biasing force produced by foam <b>366</b> may help ensure that antenna structures <b>204</b>B are placed at a well-defined location relative to the dielectric of display cover layer <b>254</b>. By placing antenna structures <b>204</b>B at this well-defined location, fluctuations in the performance of antenna structures <b>204</b>B due to placement variations within device <b>10</b> can be minimized.

0064Components <b>350</b> may be mounted on flexible printed circuit <b>340</b>. Components <b>350</b> may include capacitors such as capacitors <b>224</b> of <figref idref="DRAWINGS">FIG. 2</figref>, inductors such as inductors <b>229</b> in path <b>228</b> in <figref idref="DRAWINGS">FIG. 2</figref>, switches, inductors, capacitors, and other components that are associated with adjustable components <b>208</b> (e.g., in a scenario in which the antenna structures are tunable), matching circuit components, or other circuitry.

0065Coaxial cable <b>370</b> may be connected to transmission line conductors in flexible printed circuit tail <b>342</b> of flexible printed circuit <b>340</b> using connector <b>372</b>. Cable <b>370</b> may form part of transmission line <b>212</b> (<figref idref="DRAWINGS">FIG. 2</figref>). The transmission line conductors within tail portion <b>342</b> of flexible printed circuit <b>340</b> may be implemented using a microstrip transmission line, a stripline transmission line, or other printed circuit transmission line structure. The ground traces in the microstrip transmission line may be shorted to housing <b>12</b> and vertical housing wall <b>12</b>W. For example, fasteners such as screws <b>360</b> or other conductive structures may be used to couple the ground traces of protruding tail portion <b>342</b> of flexible printed circuit <b>340</b> to housing <b>12</b>.

0066<figref idref="DRAWINGS">FIG. 10</figref> is a cross-sectional side view of tail portion <b>342</b> of flexible printed circuit <b>340</b> taken along line <b>362</b> of <figref idref="DRAWINGS">FIG. 9</figref> and viewed in direction <b>364</b>. As shown in <figref idref="DRAWINGS">FIG. 10</figref>, transmission line <b>212</b> of <figref idref="DRAWINGS">FIG. 2</figref> may be formed from conductive structures such as positive signal conductor <b>406</b> and ground signal conductor <b>404</b>. Conductor <b>406</b> may be a metal trace that serves as positive transmission line conductor <b>214</b> of <figref idref="DRAWINGS">FIG. 2</figref>. Conductor <b>404</b> may be a metal trace that serves as ground transmission line conductor <b>216</b> of <figref idref="DRAWINGS">FIG. 2</figref>. Dielectric such as polymer layer <b>400</b> may serve as a substrate for flexible printed circuit <b>340</b>. Layer <b>400</b> may be formed from a material such as polyimide or other flexible printed circuit substrate material.

0067To ground traces such as trace <b>404</b> to housing structures such as metal housing structure <b>12</b>W, screws <b>360</b> may be coupled between trace <b>404</b> (and if desired, traces on the surface of substrate <b>400</b> that are coupled to trace <b>404</b>) and housing <b>12</b>. Screws <b>360</b> may have threaded shafts with tips that screw into threaded holes in housing <b>12</b>W such as holes <b>420</b>. Vias <b>402</b> may be used to short ground conductor trace <b>404</b> to traces forming contact pads <b>410</b>. Conductive structures <b>412</b> (e.g., foam, conductive fabric, conductive adhesive, or other conductive materials) may be used to short pads <b>410</b> (and therefore ground trace <b>404</b>) to a ground structure such as housing <b>12</b>W.

0068Dielectric member <b>408</b> may be formed from a strip of polymer such as biaxially-oriented polyethylene terephthalate or polyester films. The thickness of film <b>408</b> may be selected to establish a desired separation D between positive signal conductor trace <b>406</b> and ground structures <b>12</b>W. As an example, dielectric film <b>408</b> may have a thickness of 200 microns (or 100-300 microns or other thickness) and the distance between film <b>408</b> and conductor <b>406</b> may be 50 microns, thereby establishing a fixed separation of 250 microns between ground structures <b>12</b>W and conductor <b>406</b>. With a satisfactorily fixed and known distance D, the impedance of the transmission line that is formed using the structures of <figref idref="DRAWINGS">FIG. 10</figref> may be maintained at a desired value such as 50 ohms.

0069The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.