HK1173278B - Resonating element for reducing radio-prequency interference in an electronic device - Google Patents

Description

Resonating element for reducing radio frequency interference in electronic devices

Cross Reference to Related Applications

This application claims priority to U.S. patent application No. 13/017,568 filed on 31/2011 and to provisional patent application No. 61/431,522 filed on 11/2011, which are all incorporated herein by reference.

Technical Field

The present disclosure relates generally to electronic devices and, more particularly, to structures for reducing signal interference in electronic devices.

Background

Electronic devices such as cellular telephones and other devices often contain wireless communication circuitry. The wireless communication circuitry may include, for example, cellular telephone transceiver circuitry for communicating with a cellular telephone network. The wireless communication circuitry in the electronic device may also include wireless local area network circuitry and other wireless circuitry. The antenna structure is used in transmitting and receiving wireless signals.

Electronic devices also often include a display. For example, liquid crystal displays are commonly provided in cellular phones. The display includes an array of image pixels. For example, liquid crystal displays contain an array of image pixels based on liquid crystal materials. A controlled electric field is applied to the liquid crystal material with electrodes in an array to change its optical properties and thereby create an image on the display. Drive signals for the electrodes in the array are generated with a display drive circuit.

Challenges arise in assembling displays and wireless circuits in electronic devices. In many devices, for example, space is at a premium, thus requiring the antenna and display to be placed in close proximity to each other. Meanwhile, display driver circuits used in driving signals into the display may generate signals that interfere with the operation of the wireless circuitry.

Accordingly, it is desirable to provide a way to reduce signal interference between electronic components, such as wireless electronic device components, in an electronic device.

Disclosure of Invention

Electronic devices are equipped with displays such as liquid crystal displays. The display may have display driving circuitry that drives signals onto image pixels of the display.

The electronic device may include wireless circuitry, such as cellular telephone transceiver circuitry, and associated antenna structures. Antenna structures and transceiver circuits may be used to transmit and receive radio frequency signals. The ground plane of the antenna structure may be placed at the center of the electronic device below the display.

In order to reduce signal interference when a plurality of components are used simultaneously in an electronic apparatus, the electronic apparatus may be equipped with a resonance element serving as a structure for reducing interference. The resonator element structure may be implemented as an L-shaped structure having an arm extending parallel to one side of the display. The resonating element may be used to reduce signal interference that may otherwise be caused when a display and antenna structure or other circuitry in an electronic device are operating simultaneously.

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

Drawings

FIG. 1 is a perspective view of an illustrative example of an electronic device of the type that may be equipped with a resonating element structure according to an embodiment of the present invention.

FIG. 2 is a top view of the interior of an electronic device of the type shown in FIG. 1, in accordance with embodiments of the present invention.

Fig. 3 is a diagram of an electronic device including a resonating element structure according to an embodiment of the present invention.

Fig. 4 is a perspective view of a resonant element structure according to an embodiment of the present invention.

FIG. 5 is a perspective view of an interior portion of an electronic device of the type shown in FIG. 1 showing where a resonating element structure of the type shown in FIG. 4 may be used in accordance with an embodiment of the present invention.

Detailed Description

Electronic devices may be equipped with wireless communication circuitry. The wireless communication circuitry may be configured to support wireless communications in one or more wireless communications bands. Antenna structures in electronic devices may be used in receiving and transmitting radio frequency signals.

Fig. 1 shows an illustrative electronic device containing wireless communication circuitry. The device 10 of fig. 1 may be a laptop, tablet, computer monitor with integrated computer, desktop, or other electronic device. If desired, the electronic device 10 may be a portable device such as a cellular telephone, media player, other handheld device, wrist-watch device, pendant device, earpiece device, or other compact portable device.

As shown in fig. 1, the device 10 may have a housing such as housing 11. The housing 11 may be formed of materials such as plastic, metal, carbon fiber and other fiber composite materials, ceramic, glass, wood, other materials, or combinations of these materials. The apparatus 10 may be formed from a unitary construction in which a portion or all of the housing 11 may be formed from a single piece of material (e.g., a single cast or machined piece of metal, a single piece of molded plastic, etc.) or from a frame structure, housing sidewall structure, and other structures that can be assembled together with fasteners, adhesives, and other attachment mechanisms. In the exemplary device shown in fig. 1, the housing 11 includes a conductive peripheral housing member 12. The conductive peripheral housing member 12 may have a ring shape extending around the rectangular periphery of the device 10. One or more gaps, such as gap 30, may be formed in the conductive peripheral housing member 12. Gaps such as gap 30 may be filled with a dielectric such as plastic and may interrupt the otherwise continuous shape of the conductive peripheral housing member. The conductive perimeter housing member can have any suitable number of gaps 30 (e.g., more than one, more than two, three or more, less than three, etc.).

The conductive peripheral housing member 12 may be formed of a durable material such as metal. The housing member 12 may be formed from stainless steel, as it is aesthetically pleasing, rigid, and machinable in manufacture. Other metals may be used if desired. The back of the housing 11 may be formed of plastic, glass, metal, ceramic composite, or other suitable material. For example, the back of the housing 11 may be formed from a glass plate having regions supported by an internal metal layer for increased strength. The conductive perimeter housing member 12 may be relatively short in the vertical dimension z (e.g., to serve as a bezel for a display) or may be taller (e.g., to serve as a sidewall of the housing 11 as shown in the exemplary configuration of fig. 1).

Device 10 may include components such as buttons, input-output port connectors, ports for removable media, sensors, microphones, speakers, status indicators, and other device components. As shown in FIG. 1, for example, device 10 may include buttons such as menu button 16. Device 10 may also include a speaker port (e.g., to serve as an ear speaker for device 10) of speaker port 18.

One or more antennas may be formed in the device 10. For example, antennas may be formed in locations such as locations 24 and 26 to provide spacing from conductive elements of display 14. The antenna may be formed with a single-band or multi-band antenna structure. Examples of communication bands that an antenna may cover include cellular telephone bands (e.g., bands 850MHz, 900MHz, 1800MHz, 1900MHz, and 2100MHz), satellite navigation bands (e.g., Global positioning System band 1575MHz), such as IEEE 802.11Frequency bands of 2.4GHz and 5GHz of a wireless local area network, a Bluetooth frequency band of 2.4GHz and the like. Examples of antenna configurations that may be used for the antennas in device 10 include monopole antennas, dipole antennas, strip antennas, patch antennas, inverted-F antennas, coil antennas, planar inverted-F antennas, open slot antennas, closed slot antennas, loop antennas, hybrid antennas including multiple types of antenna structures, or other suitable antenna structures.

Device 10 may include one or more displays such as display 14. The display 14 may be a Liquid Crystal Display (LCD), an Organic Light Emitting Diode (OLED) display, a plasma display, an electronic ink display, or the like. The touch sensor may be incorporated into the display 14 (i.e., the display 14 may be a touch screen). The touch sensor may be an acoustic touch sensor, a resistive touch sensor, a piezoelectric touch sensor, a capacitive touch sensor (e.g., a touch sensor based on an indium tin oxide capacitor electrode array), or a touch sensor based on other touch technologies.

The display 14 may be covered by a transparent planar conductive member such as a glass or plastic layer. The cover layer for display 14, which is sometimes referred to as a cover glass layer or cover glass, may extend over substantially the entire front face of device 10 as shown in FIG. 1. The rectangular central portion of the cover glass (the portion surrounded by the dashed line in fig. 1) contains the image pixel array and is sometimes referred to as the active portion of the display 14. The outer peripheral portion of the cover glass (i.e., the rectangular peripheral ring 22 of fig. 1) does not include any moving image pixels and is sometimes referred to as the inactive portion of the display 14. A patterned opaque barrier layer, such as a ring around black ink, may be formed under the inactive portion 22 to hide internal device components from view by a user.

Fig. 2 is a top view of the interior of electronic device 10, showing how antennas 40L and 40U are implemented in housing 12. As shown in fig. 2, a ground plane G is formed in the housing 12. Ground plane G may form the antenna ground for antennas 40L and 40U. Since ground plane G may serve as an antenna ground, ground plane G is sometimes referred to as an antenna ground, or ground plane element (as examples). One or more printed circuit boards or other mounting structures may be used to mount components 31 in device 10. Components 31 may include radio frequency transceiver circuitry, processors, application specific integrated circuits, cameras, sensors, switches, connectors, buttons, and other electronics components coupled to antennas 40U and 40L using transmission lines 52L and 52U.

In the central portion C of the device 10, the ground plane G may be formed by a conductive structure (sometimes referred to as an inner housing plate or planar inner housing structure) such as a conductive housing mid-plate member. The ground plane G may be configured to be connected between the left and right edges of the member 12. A printed circuit board with conductive ground traces (e.g., one or more printed circuit boards for mounting the component 31) may form part of the ground plane G.

The intermediate plate member may have one or more individual sections (e.g., patterned sheet metal sections) welded together. Portions of the intermediate plate structure may be covered by insert-molded plastic (e.g., to provide structural support in portions of the interior of the device that do not require conductive grounding, such as the dielectric filled portions of antennas 40U and 40L in regions 24 and 26).

At the ends 24 and 26 of the device 10, the shape of the ground plane G may be determined by the shape and location of the conductive structures connected to ground. The ground plane G in the simplified layout of fig. 2 has a straight upper edge UE and a straight lower edge LE. In actual devices, the upper and lower edges of the ground plane G and the inner surface of the conductive perimeter housing member 12 typically have more complex shapes determined by the shape of the individual conductive structures present in the device 10. Examples of conductive structures that overlap to form the ground plane G and that may affect the shape of the inner surface of the member 12 include housing structures (e.g., conductive housing mid-plane structures, which may have raised portions), conductive components (e.g., switches, cameras, data connectors, printed circuits such as flexible circuits and rigid printed circuit boards, radio frequency shielding cans, buttons, and conductive button mounting structures), and other conductive structures in the device 10. In the illustrative layout of fig. 2, the portions of device 10 that are conductive and connected to ground to form a portion of ground plane G are shaded and border central portion C.

Openings (sometimes referred to as gaps), such as openings 138 and 140, may be formed between various portions of the peripheral conductive housing member 12 and the ground plane G. Openings 138 and 140 may be filled with air, plastic, and other dielectrics. Openings 138 and 140 may be associated with antenna structures 40U and 40L.

The lower antenna 40L may be formed from a loop antenna structure having a shape determined at least in part by the shape of the ground plane G and the lower portion of the conductive housing member 12. In the example of fig. 2, the opening 138 is depicted as being rectangular, but this is merely illustrative. In practice, the shape of opening 138 may be dictated by the placement of conductive structures (such as microphones, flex circuit traces, data port connectors, buttons, speakers, etc.) in region 26.

The lower antenna 40L may be fed using an antenna feed, which may be comprised of a positive antenna feed terminal 58L and a ground antenna feed terminal 54L. The transmission line 52L may be coupled to the antenna feed of the lower antenna 40L. Gap 30' may form a capacitance that helps configure the frequency response of antenna 40L. If desired, device 10 may have conductive housing portions, matching circuit elements, and other structures and components that help match the impedance of transmission line 52L to antenna 40L.

Antenna 40U may be a dual-branch inverted-F antenna. Transmission line 52U may be used to feed antenna 40U at antenna feed terminals 58U and 54U. The conductive structure 150 may form a short circuit path that bridges the dielectric opening 140 and electrically shorts the ground plane G to the peripheral housing member 12. Conductive structure 148 (which may be formed with a structure of the type used in forming structure 150 or other suitable structure) and matching circuit M may be used to connect antenna feed terminal 58U to perimeter conductive housing 12 at point 152. Conductive structures (sometimes referred to as conductive paths) such as structures 148 and 150 may be formed from flex circuit traces, conductive housing structures, springs, screws, solder connections, solder joints, brackets, metal plates, or other conductive structures.

There may be gaps such as gaps 30 ', 30 ", 30'" in the peripheral conductive member 12 (e.g., gap 30 of fig. 1). Phantom gap (phantom gap) may be provided in the lower right hand portion of device 10 for aesthetic symmetry, if desired. The presence of the gaps 30 ', 30 ", 30'" may divide the peripheral conductive housing member 12 into segments. As shown in FIG. 2, the peripheral conductive member 12 may include a first segment 12-1, a second segment 12-2, and a third segment 12-3.

Segment 12-1 may form a resonating element arm of antenna 40U. In particular, a first portion (segment) of segment 12-1 may extend from point 152 (where segment 12-1 is fed) to one end of segment 12-1 defined by gap 30 ", and a second portion (segment) of segment 12-1 may extend from point 152 to an opposite end of segment 12-1 defined by gap 30'". The first and second portions of segment 12-1 may form respective branches of an inverted-F antenna and may be associated with Low Band (LB) and High Band (HB) antenna resonances, respectively, of antenna 40U. The long relative position of structures 148 and 150 along member 12-1 may affect the response of antenna 40U and may be selected to tune antenna 40U. Antenna tuning adjustments may also be made by adjusting the matching circuit M, by adjusting the configuration of components used in forming the paths 148 and 150, by adjusting the shape of the opening 140, and so forth. The antenna 40L may also be similarly adjusted.

Using one illustrative configuration, antenna 40L may cover transmit and receive sub-bands in 5 communication bands (e.g., 850MHz, 900MHz, 1800MHz, 1900MHz, and 2100 MHz). As an example, antenna 40U may be configured to cover a subset of the 5 illustrative communication bands. For example, antenna 40U may be configured to cover 2 receive bands of interest and, by tuning, four receive bands of interest.

As shown in fig. 3, display 14 may include a display module 160. When enclosed in the device 10 of fig. 1, the display module 160 may be mounted under a cover layer such as a plastic layer or a glass layer (cover glass). Display module 160 (also sometimes referred to as a display) may include display driver circuit 161. Display driver circuit 161 may be used to drive signals into the display (e.g., circuit 164). For example, display module 160 may be a liquid crystal display including a color filter array, a layer of liquid crystal material, and an array of image pixel electrodes and associated thin film transistors (e.g., a thin film transistor layer). The display driver circuitry may include a driver integrated circuit mounted at one end of the thin-film-transistor layer. The circuitry 164 may include an array of thin film transistors and control lines for distributing signals from the display driver circuitry to the display.

The components 31 (fig. 2) may include radio frequency transceiver circuitry (e.g., one or more cellular telephone receivers, one or more cellular telephone transmitters, and receivers and transmitters associated with other frequency bands, etc.). In radio frequency transmission using a radio frequency transmitter, radio frequency signals may be transmitted through an antenna in device 10. For example, antenna 40L may transmit cellular telephone signals, some of which may be coupled into control lines and other circuitry of display 164. During operation of the driver circuit 161, the drive signal from the driver circuit 161 may be mixed with a signal from a cellular telephone transmitter (or other wireless transmitter). This may result in unwanted mixing products (e.g., intermodulation distortion or IMD). Whenever the display and cellular circuitry in device 10 are used simultaneously, the mixing products may have frequencies that fall within one or more of the receive bands (or other wireless communication bands of interest) of the cellular telephone receiver in device 10 and thus act as a form of unwanted signal interference.

To reduce unwanted signal interference in device 10 (e.g., to reduce interference between an antenna in device 10 and display 14 or to reduce interference between other components in device 10), one or more resonating element structures, such as resonating element structure 162, are provided in device 10. A resonating element structure such as structure 162 has antenna-like properties because it resonates most strongly near a particular electromagnetic signal frequency. In an antenna, a resonant element emits radiation (during signal transmission operations) and receives radiation (during signal reception operations) in a particular communication frequency band. In a passive structure such as the resonant element 162, no active signaling operation is performed (i.e., the transmission line does not feed the element 162 as does an antenna), but the resonant element 162 still exhibits a frequency response (peak signal absorption) centered approximately at a particular frequency due to its geometry (e.g., its length relative to the wavelength of the received electromagnetic signal) and its position relative to the ground plane G. In the example of fig. 3, structure 162 has been placed adjacent antenna 40L, but a resonating element such as resonating element 162 may be placed elsewhere in the housing of device 10 if desired.

Figure 4 is a perspective view of the resonant element structure 162 showing how the structure 162 has a resonant element arm, such as arm 162-1, that extends parallel to the surface of the ground plane G at height H. The branch 162-2 of the structure 162 extends parallel to the surface orthogonal to the ground plane G (i.e., extends parallel to the Z-axis) and may electrically connect the arm 162-1 and the ground plane G. Portion 162-3 of structure 162 may be bent at a right angle to branch 162-2. The structure 162 may be attached to the ground plane G using solder, such as solder joints 166 or other fastening arrangements. Structure 162 may be formed from a metal strip or other suitable conductive element. The structure of the ground plane G may include one or more electrically connected metal (e.g., stainless steel) sheets. Structure 162 may also be formed of stainless steel, copper, gold-plated copper, or other suitable conductor.

Using the illustrative configuration for structure 162 shown in fig. 4, structure 162 forms an L-shaped resonating element that resonates (absorbs electromagnetic energy) at a frequency related to its size (e.g., the same frequency as the quarter-wavelength L-shaped antenna resonating element). It has been determined that when the length L of the structure 162 is in the range of about 2 to 4cm, interference due to mixing products generated when simultaneously transmitting cellular telephone signals and operating the display 14, which otherwise would adversely affect cellular telephone signal reception, is greatly reduced. One possible mechanism for reducing interference is to reduce electromagnetic energy that will be coupled into display 14 from antenna 40L during signal transmission operations, which may occur when some of the transmitted energy is not dissipated in resonating element 162. Other interference reduction mechanisms may also be included.

A reduction in interference may be experienced at an antenna structure (e.g., antenna 40L) adjacent structure 162 and/or at an antenna structure (e.g., antenna 40U) at the other end of device 10. If desired, the structure 162 may have a shape other than the illustrative shape of FIG. 4 (e.g., a shape in which the arm 162-1 is bent to form a structure having multiple parallel and/or perpendicular portions with one, two, three, or more bends, a shape having a bent portion, a shape having multiple arms, etc.).

Fig. 5 is a perspective view of device 10 in the vicinity of antenna 40L and structure 162. The structure 162 may extend across the width of the device 10 parallel to the lower edge LE of the ground plane G. As shown in fig. 5, the arms of structure 162 need not be rectangular and may include holes, cut-out regions (e.g., curved portions that can accommodate an opening for button 16 of fig. 1), etc. A plastic layer may be interposed between the arm 162-1 and the ground plane G (e.g., to support the arm 162-1 at a desired height value H). Other dielectrics may be placed between arm 162-1 and ground plane G if desired. There may be any suitable number of structures 162 in device 10 (e.g., one at the lower end 26, one at the upper end 24, one at each end of device 10, etc.).

According to one embodiment, there is provided an electronic device including: a display, an antenna, and a resonating element structure that reduces signal interference associated with simultaneous operation of the display and the antenna.

According to another embodiment, the display has edges, the electronic device comprises a ground plane forming part of the antenna, and the resonant element structure comprises an L-shaped structure having an arm extending parallel to at least one of the edges of the display.

According to another embodiment, the display has edges, the electronic device includes a ground plane forming part of the antenna, and the resonant element structure includes an L-shaped structure having an arm and a leg, the arm extending parallel to at least one of the edges of the display and the leg extending substantially perpendicular to the ground plane.

According to another embodiment of the invention, the electronic device further comprises a peripheral conductive housing member, at least a portion of which forms a part of the antenna.

According to another embodiment of the present invention, the electronic device further comprises: a ground plane forming a portion of the antenna, and a peripheral conductive housing member, a portion of the peripheral conductive housing member being isolated from the ground plane by a dielectric-filled aperture, wherein the portion of the peripheral conductive housing member forms a portion of the antenna.

According to another embodiment, a resonant element is interposed between the display and the dielectric filled aperture.

According to another embodiment, the display has edges and the resonant element structure comprises an L-shaped structure having arms extending parallel to at least one of the edges of the display.

According to another embodiment, the L-shaped structure has branches extending perpendicular to the ground plane and perpendicular to the arms.

According to another embodiment said branches are connected to said ground plane.

According to another embodiment, the branches are soldered to the ground plane.

According to another embodiment, the electronic device further comprises: a ground plane associated with the antenna, wherein the resonating element structure comprises an L-shaped structure having an arm and a branch, the arm overlapping the ground plane and the branch being connected to the ground plane; and a plastic interposed between the arm and the ground plane.

According to another embodiment, the electronic device further comprises: a display driver circuit in the display; and cellular telephone radio frequency transceiver circuitry coupled to the antenna, the cellular telephone radio frequency transceiver circuitry to transmit radio frequency signals using the antenna and to receive radio frequency signals using the antenna, wherein the resonant element structure is configured to reduce interference in received radio frequency signals when the display driver circuitry is operated while transmitting the radio frequency signals.

According to one embodiment, there is provided an electronic device including: a housing, a ground plane forming a portion of an antenna, an electronic component having at least one edge, and a resonating element structure having a branch and an arm, the branch being connected to the ground plane and the arm extending parallel to the edge above the ground plane and reducing signal interference associated with operating the antenna and the electronic component.

According to another embodiment, the electronic component comprises a display and the resonant element structure comprises an L-shaped structure.

According to another embodiment, the electronic device further comprises a peripheral conductive housing member surrounding the housing and forming part of the antenna, wherein the ground plane and the peripheral conductive housing member are separated by a dielectric filled gap.

According to another embodiment, the arms extend parallel to the dielectric-filled gaps and the arms are electrically coupled to the ground plane through the branches.

According to one embodiment, there is provided an electronic device including: a housing, a display mounted in the housing, at least one upper antenna located at an upper end of the housing above the display; at least one lower antenna located at a lower end of the housing below the display; and a resonating element structure configured to reduce interference between at least one of the display and the antenna.

According to another embodiment, the electronic device further comprises: a rectangular ring-shaped conductive perimeter housing member surrounding said housing, wherein said upper and lower antennas are formed from portions of said ground plane and said conductive perimeter housing member.

According to another embodiment, the resonating element structure is interposed between the lower antenna and the display and includes an arm and a branch, the arm extending parallel to an edge of the display and the branch being connected to the ground plane.

According to another embodiment, the electronic device comprises a handheld electronic device, the electronic device further comprising: a display driver circuit in the display; and cellular telephone radio frequency transceiver circuitry coupled to the upper and lower antennas, wherein the resonant element structure is configured to reduce interference in radio frequency signals received using at least one of the antennas when the display driver circuitry is operated while simultaneously transmitting radio frequency antenna signals using the cellular telephone radio frequency transceiver circuitry.

The 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.

Claims (16)

1. An electronic device, comprising:

a display;

an inverted-F antenna; and

a resonating element structure separate from the inverted-F antenna, separate from the display, and disposed in a position such that the resonating element structure substantially reduces signal interference associated with simultaneous operation of the display and the antenna, wherein the resonating element structure is not fed by any transmission lines.

2. The electronic device defined in claim 1 wherein the display has edges, the electronic device comprises a ground plane that forms part of the antenna, and the resonant element structure comprises an L-shaped structure having arms with longitudinal axes that extend parallel to at least one of the edges of the display, wherein the resonant element structure further comprises branches that extend perpendicular to the arms between the ground plane and the edges of the arms, and wherein the edges of the arms are located at a first end of the longitudinal axes of the arms.

3. The electronic device defined in claim 1 wherein the display has edges, the electronic device comprises a ground plane that forms part of the antenna, and the resonant element structure comprises an L-shaped structure having an arm and a branch, the arm extending parallel to at least one of the edges of the display and the branch extending substantially perpendicular to the ground plane.

4. The electronic device defined in claim 3 further comprising a peripheral conductive housing member, at least a portion of which forms a portion of the antenna.

5. The electronic device of claim 1, further comprising:

a ground plane forming part of the antenna, an

A peripheral conductive housing member, a portion of which is isolated from the ground plane by a dielectric-filled aperture, wherein the portion of the peripheral conductive housing member forms a portion of the antenna.

6. The electronic device defined in claim 5 wherein the resonating element is interposed between the display and the dielectric-filled aperture.

7. The electronic device defined in claim 6 wherein the display has edges and the resonant element structure comprises an L-shaped structure having arms that extend parallel to at least one of the edges of the display.

8. The electronic device defined in claim 7 wherein the L-shaped structures have branches that extend perpendicular to the ground plane and perpendicular to the arms.

9. The electronic device of claim 8 wherein the branch is connected to the ground plane.

10. The electronic device of claim 9 wherein the branches are soldered to the ground plane.

11. The electronic device of claim 1, further comprising:

a ground plane associated with the antenna, wherein the resonating element structure comprises an L-shaped structure having an arm and a branch, the arm overlapping the ground plane and the branch being connected to the ground plane; and

a plastic interposed between the arm and the ground plane.

12. The electronic device of claim 11, further comprising:

a display driver circuit in the display; and

a cellular telephone radio frequency transceiver circuit coupled to the antenna, the cellular telephone radio frequency transceiver circuit to transmit radio frequency signals using the antenna and to receive radio frequency signals using the antenna, wherein the resonant element structure is configured to reduce interference in received radio frequency signals when the display driver circuit is operated while transmitting the radio frequency signals.

13. An electronic device, comprising:

a housing;

a display mounted in the housing;

at least one upper antenna located at an upper end of the housing above the display;

at least one lower antenna located at a lower end of the housing below the display, wherein the at least one lower antenna comprises a loop antenna; and

a resonating element structure configured to reduce interference between the display and the loop antenna, wherein the resonating element structure is not fed by any transmission lines.

14. The electronic device of claim 13, further comprising:

a rectangular ring-shaped conductive perimeter housing member surrounding said housing, wherein said upper and lower antennas are formed from respective portions of said conductive perimeter housing member and a ground plane.

15. The electronic device defined in claim 14 wherein the resonating element structure is interposed between the lower antenna and the display and comprises an arm and a branch, the arm extending parallel to an edge of the display and the branch connecting to the ground plane.

16. The electronic device defined in claim 15 wherein the electronic device comprises a handheld electronic device, the electronic device further comprising:

a display driver circuit in the display; and

a cellular telephone radio frequency transceiver circuit coupled to the upper and lower antennas, wherein the resonant element structure is configured to reduce interference in radio frequency signals received using at least one of the antennas when the display driver circuit is operated while simultaneously transmitting radio frequency antenna signals using the cellular telephone radio frequency transceiver circuit.