GB2390957A

GB2390957A - System for enhanced radiation performance of a communication device

Info

Publication number: GB2390957A
Application number: GB0316053A
Authority: GB
Inventors: Amin T Jalali; Adrian Napoles; Neil J Schmertmann; Paul Morningstar; Naveed Mirza; De Leon Lorenzo A Ponce; Christos Kontogeorgaki
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 2002-07-15
Filing date: 2003-07-09
Publication date: 2004-01-21
Anticipated expiration: 2023-07-09
Also published as: GB0316053D0; CN1477896A; CN1232150C; GB2390957B; TW200419940A; TWI325237B

Abstract

A system (115) provides enhanced radiation performance for a communication device (10). The system (115) includes one or more shields (90) for directing radio frequency energy. The one or more shields (90) are isolated from the radio frequency currents on the ground plane of the communications device (10). The system (115) further includes a display bezel (60) also isolated from the radio frequency currents on the ground plane. The system (115) further includes one or more impedance blocks electrically connected between the display bezel (60) and a printed circuit board (25) for providing a direct current ground path between the display bezel (60) and the printed circuit board (25) and for providing radio frequency isolation between the display bezel (60) and the printed circuit board (25).

Description

System for Enhanced Radiation Performance of a Communication Device

Background of the Invention

5 Field of the Invention

This invention relates in general to communication devices and in particular to communication devices having a system for enhanced radiation performance.

10 Descrintion of the Related Art The manner in which communication devices such as cellular telephones are utilized affects their radiated performance. Typically, a user positions the communication device against his/her head, aligning the device microphone with 15 bis/her mouth to facilitate speaking into the microphone, and aligning the device earpiece to his/her ear to facilitate listening to the output signal generated by the earpiece. Some cellular telephones are equipped with a speaker used for hands free operation. In hands free operation, during a cellular conversation, the cellular telephone is located at some fixed distance from the user. Variations in the local 20 environment of the cellular telephone such as herein described affects its radiated performance. The radiated performance then directly impacts the quality of the service provided by a cellular phone or other communication device. Communication devices such as cellular phones must meet regulatory and industrymandated standards.

Regulatory agencies dictate the maximum amount of radiated power that a

communication device can transmit in a designated frequency band, the maximum amount of radiated emissions that are allowed outside the operational frequency band, and also the allowable limits on Specific Absorption Rates or energy deposition.

Industry standards follow the regulatory standards and also dictate the minimum 5 allowable radiated levels for a giver. operational frequency band. In combination, these standards for communication devices constrain both the maximum and minimum power that a communication device can transmit, the maximum out of band radiated emissions, and the maximum levels of energy deposition.

In order to gauge how mall a communication device works in the field,

10 manufacturers of such devices assess their radiation performance with a variety of radiated tests. Device manufacturers measure the effective radiated power (ERP) of their products in "free field." Manufacturers measure the ERP of their products when

placed next to a phantom (emulating the human head and body) in a "talk mode".

Manufacturers also measure the ERP of their products in a variety of other user 15 positions. Typically, ERP in the free field is many decibels higher than in talk mode.

Manufacturers measure the energy deposition of the product using a simulated anthropomorphic mannequin (SAM) phantom and the industry standard measurement procedures. The conflict between maximizing radiated power to meet the ERP tests and nirumizlng energy deposition creates difficult design challenges to 20 corornunication device manufacturers. It is known that decreasing the transmitter output power decreases energy deposition of a communication device. Decreasing the transmitter output power also reduces the ERP. For example, in order to meet the requirements for energy deposition, a manufacturer may have to reduce the ERP of its

cornmuriication device. In such a situation' the reduction in ERP reduces the range of the communication device and negatively impacts the quality of the service. order to meet the electromagnetic compliance (EMC) standards for unwanted out of band radiation, manufacturers utilize venous shielding methods to reduce emissions from 5 the communication device. For example conductive paint is applied in a relatively random fashion on plastic housing of conunucation devices to provide shielding andlor for cosmetic purposes alone. Current approaches, however, neither identify nor address the potential affects on energy deposition from such shielding.

Communication device designers are also concerned with minimizing the 10 detrimental electrostatic discharge (ESD) effects of metal elements of the device on ESD sensitive components. For example, many communication devices utilize a metal bezel around the perimeter of the display for mechanical stability and protection of the display. Typically, the metal bezel is mechanically and electrically connected to the conductive components of We radio chassis (such as the printed circuit (PC) 15 board ground plane). One disadvantage ofthis connection is that it provides a path for RF currents to flow Trough the display and ultimately increase energy deposition.

As advances in technology have pennitted communication devices to be made smaller in size and lighter in weight, the available space for implementing necessary radiation enhancing features to meet the performance requirements detailed above becomes 20 limited, creating Farther challenges for device manufacturers.

Brief Description of the Drawings

The present invention will be described by way of exemplary embodiments, but not limitations, illustrated in the accompanying drawings in which like references 5 denote similar elements, and in which: FIG. I illustrates a communication device.

FIG. 2 illustrates a cross section view of a shield for use within the communication device of FIG. I in accordance with the present inventior'.

FIG. 3 illustrates system for enhanced radiation performance for use witn:Yi 10 the communication device of FIG. I in accordance with the present invention.

FIG. 4 illustrates a radiated frequency current distribution within the communication device of FIG. 1 in accordance with the present invention.

FIG. 5 illustrates an electrostatic current path within the communication device of FIG. 1 in accordance with a preferred ernbodinent of the present invention.

15 FIGs. 6 and 7 illustrate the system for enhanced radiation perfonnance of FIG. 3 as implemented in various embodiments of the communication device of PIG. 1.

FM. 8 illustrates one embodiment of a shield for use within the communication device of FIGs. I through 7 in accordance with the present invention.

FIG. 9 illustrates more detail of the shield of FIG. 8 in accordance with the 20 present invention.

FIGs. 10 through 15 illustrate various alternative embodiments of the shield of FIGs. 8 and 9 in accordance with the present invention.

FIGs. 16 through 18 illustrate various alternative embodiments of the shield of Flus. 8 and 9 for a display portion of the communication device of FIG. 1 in accordance with the present invention.

5 Detailed Description Of The Preferred Embodiment(s)

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific 10 structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the

15 invention.

The terms a or an, as used herein, are defined as one or more than one. The tend plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language). The term 20 coupled, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. The term program, as used herein, is defined as a sequence of instructions designed for execution on a computer system. A program, or computer program, may include a subroutine, a fimction, a procedure, an object s

method, an object implementation, an executable application, an apples, a servlet, a source code, an object code, a shared library/dynamic load library and/or other sequence of instructions designed for execution on a computer system.

FIG. I illustrates a comm Location device 10, in accordance with the present 5 invention. The communication device 10 preferably is a voice communication device.

The communication device 10, for example, can be a cellular telephone (as illustrated), a cordless telephone, a wired landline telephone, or a personal communicator such as the V200 Personal Communicator manufactured by Motorola Inc. of Schaumburg, Illinois. In the following description, the term "cocmnrtirn

10 device" refers to any ofthe communication devices mentioned above or an equivalent.

The communication device 10 preferably includes a front housing 20 and a back housing 30. The role of the front housing 20 and the back housing 30 in the communication device 10 primarily includes covering, protecting and supporting a plurality of components such as those within a printed circuit (PC) board 25 encased 15 within. Along with the plurality of components, the printed circuit board 25 includes a ground plane coupled to the plurality of components for grounding the plurality of components. It will be appreciated by those of ordinary skill in the art that both radio frequency (RF) currents and direct (DC) currents flow through the ground plane. The communication device further includes a battery 35 typically located within or 20 adjoining the back housing 30. The communication device 10 further includes an antenna 45, a display 40, a display bezel 60, a display lens 70, a speaker 50, and a keypad assembly 80 typically located within or adjoining the front housing 20. The keypad assembly 80 allows the user ofthe communication device 10 to enter data

such as phone numbers and text memos. The display 40 displays data such as one or more communication messages, phone numbers, or caller identifications. The display 40 can be, for example, a liquid crystal display utilized to display text. It will be appreciated by one of ordinary skill in the art that other similar displays such as dot 5 matrix displays can be utilized for the display 40. The display bezel 60 provides mechanical Support and protection to the display 40. The display lens 70 can be decorative to provide ornamental design customization around the display 40 and also can provide protection to the face of the display 40.

In accordance with the present invention, the communication device 1^ 10 preferably further includes one or more shields 90 on one or more surfaces of the communication device 10. In accordance with the present invention, when more than one shield is incorporated, the plurality of shields are electromagnetically coupled to each. The one or more shields 90 are preferably located within the front housing 20 of the communication device 10. The one or more shields 90 preferably extend over at 15 least a majority of the front side of the cornmucation device 1O, substantially solar in size to the front housing 20. It will be appreciated by those of ordinary skill in the art that the one or more shields 90 can further extend over one or more other sides of the communication device 10 in accordance with the present invention. As illustrated in a cross sectional view in FIG. 2, the one or snore shields 90 preferably are 20 comprised of a conductive layer 100 and a dielectric layer 110 that mechanically supports the shield. The dielectric layer 110 can be a polycarbonate designed for mechanical support and forms part of the front housing 20 or back housing 30, or can be a material whose electrical characteristics are selected to further enhance the shield

performance. The one or more shields 90 redirect radio frequency (RF) energy outward from the surface of the commumcation device 10 and specifically away from the person using the communication device 10. The one or more shields 90 behave as a director or reflector, allowing the one or more shields 90 to be placed either on the 5 front side or the back side of the communication device 10 depending upon the desired radiated energy direction. The behavior of the one or more shields 90 cause the radiated energy emitted through the antenna 45 to point away from the device user (i.e. emit energy through the back housing 30 when substantially located within the front housing 20). The one or more shields 90 further can null out the magnetic neat 10 field, thereby reducing energy deposition.

In one embodiment of the present invention, the one or more shields 90 are integrated into the front housing 20 ofthe communication device 10 of FM. 1. The back housing 30 remains unshielded to provide a radiating surface for the emitted energy. The one or more shields 90 each preferably comprise a floating shield that 15 covers most of the openings of the Wont housing 20. [he one or more shields 90 are floating in the electrical sense by not making electrical contact with the antenna 45 ground typically consisting of the printed circuit board 25 ground and any grounded and/or metal elements attached thereto. The one or more shields 90 therefore are isolated fiom the radio frequency currents that flow on the ground plane and other 20 metal components of Me punted circuit board 25 by ohmic or conductive contact.

The one or more shields 90 are electromagnetically coupled to the ground plane as well as the other components.

The one or more shields 90 can be one or more individual stand-alone elements of the communication device lo, one or more attachments to the communication device 10 (such as a belt clip, protective case, or holster) , or alternatively can be integrated into the front housing 20 or the back housing 30 of the 5 communication device 10. For example, the one or more shields 90 can be created by molding the front housing 20 out of conductive plastic, by sputtering, painting, or vacuum depositing a conductive layer onto the surface of the front housing 20.

Similarly the one or more shields 90 can be created by constructing the front housing 20 out of a metal, or by placing a metallic element on the inside, middle, or outer 10 surface ofthe front housing 20. For example, metal inserts, molded wires, molded wire screen, conductive oxide or carbon layers or any combination thereto can be molded into the front housing 20. It will be appreciated by those of ordinary skill in the art that the one or more shields 90 can be created using any combination as described previously herein or an equivalent.

15 Although the invention is described such that the one or more shields 90 are packaged on the front side ofthe communication device 10 (i.e. within the front housing 20), it will be appreciated by those of ordinary skill in the art that alternatively it can be located on the back side of the communication device 10 (i.e. within the back housing 30). For example, in a communication device 10 in which 20 the speaker 50 and a microphone are located on the back side of the communication device 10 such that the user speaks with the display 40 away from the user's head, the one or more shields 90 can be located on the back side such as within the back

housing 30 using equivalent techniques to those described previously herein for the front housing 20.

Similarly, in accordance with the present invention, when the communication device 10 includes a moveable flip, the flip can be shielded over selective areas to 5 reduce energy deposition by including the one or more shields 90 substantially within the flip. In such a communication device 10, the flip may not radiate if it only contains the speaker 50. Here the display 40 and the keypad assembly 80 can be shielded, while the flip portion can remain unshielded. In a cornnunication device 10 in which the flip houses both the antenna Is and the display 4), the surface of th.c Up 10 facing outwards is shielded. The base of the communication device 10, which contains the printed circuit board 25 and the keypad assembly 80, for example can be left unshielded to form the radiating surface.

FIG. 3 illustrates a cross sectional view of a system 115 for enhanced radiation perfonnance in the communication device 10 in accordance with the present 15 invention. As illustrated in FIG. 3, the system 115 within the communication device 10 includes the one or more shields 90, a spacer 120, the display bezel 60, and one or more impedance blocks such as a first impedance block 125, a second impedance block 130, andlor a third impedance block 135.

The one or more shields 90 of the system 115 enhance the radiation performance 20 of the communication device 10 as described previously herein. The spacer 120, mechanically located between the one or more shields 90 and the display bezel 60, can be an insulator, gasket, or an equivalent for controlling a separation distance between the one or more shields 90 and the display bezel 60. The spacer 120, in accordance

with the present invention, is located such that RF currents are prevented from conductively flowing from the display bezel 60 to the one or more shields 9O Adjusting the separation between the one or more shields 90 and the conductive materials in the communication device 10 adjusts the effect the performance of the 5 one or more shields 90. A minimum distance between the conductive materials of the communication device 10 and the one or more shields 90 is required for the one or more shields 90 to be effective. In typical applications, as illustrated in FIG. 3, the metal display bezel 60 is the nearest conductive material to the one or more shields 90. The space 120 therefore is utilized to control the performance effects 'oily creating 10 an optimum distance between the one or more shields DO and the nearest conductive element. The display bezel 60 preferably is a metal display bezel isolated from the RF current flow ofthe components ofthe communication device 10. In other words, the display bezel 60, in accordance with a preferred embodiment of the present invention, 15 is electrically floating, thereby preventing the flow of RF currents through the display bezel 60 and the circuit ground of the communication device 10 located on the printed circuit board 25. When Me metal display bezel 60 is isolated from the RF current flow (or open circuited for RF purposes), the effective distance from the human body of the device user to the source of RF is increased.

20 Preferably, and in accordance with the present invention, one or more impedance blocks such as the first impedance block 125 and the second impedance block 130 are utilized to isolate the display bezel 60 Rom the printed circuit board 25 of the communication device 10. The one or more impedance blocks between the

display bezel 60 and the printed circuit board 25 provide a direct current (DC) ground path while simultaneously providing RF isolation. By using the one or more impedance blocks to isolate the metal display bezel 60, the display bezel 60 is decoupled from the conductive traces on the printed circuit board 25. effect, the 5 distance between the metal portions of the communication device 10 that carry a significant amount of the RF currents and the one or more shields 90 is increased.

Additionally beneficial, the ohmic connections established using the one or more impedance blocks further provide ESD protection to the display 40 by providing a path for charge to flow around the display 40 arid also choke ofithe radio ir.quency 10 (RF) currents. The one or more impedance blocks 125,130 comprise a frequency dependent impedance that can be used to adjust the coupling between the display bezel 60 and the printed circuit board 25 for each frequency band in which the communication device 10 operates. They are used to optimize the frequency response of the one or more shields 90 and the frequency response of the display bezel 60. As a 15 further benefit, the one or more impedance blocks also provide a path to guide the flow of electrostatic discharge currents away from Me display 40 (see FIG. 1).

At least one impedance block of the one or more impedance blocks such as the third impedance block 135 of FIG. 3 preferably is mechanically located between the one or more shields 90 and the printed circuit board 25 in accordance with the present 20 invention to provide coupling control between the one or more shields 90 and the printed circuit board 25. This impedance block can, for example, contact the one or more shields 90 and the printed circuit board 25 via a contact mechanism such as a spring or any other contacting means as is well lmown in the art. In accordance with

the present invention, the at least one impedance block such as the third impedance block 135 comprises a frequency dependent impedance, wherein adjusting the frequency dependent impedance adjusts the coupling between the one or more shields 90 and the printed circuit board 25 for one or more frequency bands.

5 It will be appreciated by those of ordinary skill in the art that multiple impedance blocks can be used to create RF open circuits at all frequency bands of interest between both the one or more shields 90 and the printed circuit board 25 and between the display bezel 60 and the printed circuit board 25. It will further be appreciated by those of ordinary skill in the ar- that the multiple inp;-._e- bloc!-. c;: 10 comprise any combination of inductors, transmission lines, and/or tuned networks to lower the RF currents on the display bezel 60 and/or on the one or more shields 90.

The combination of the floating shield and the floating metal bezel can reduce the energy deposition of the communication device 10. The present invention, as described herein, uses the one or more impedance blocks to virtually increase the 15 distance between a device user's body and a communications device, creating electrical performance better than prior art for the given mecharucal dimensions.

FIG. 4 illustrates the RF current distribution within the communication device 10 in accordance with the present invention. As illustrated, RF currents flow on the one or more shields 90 in such a way as to counter the currents generated on Me metal 20 portions of the communication device 10. As illustrated, a shield current distribution 140 is out of phase with a conductive elements current distribution 145. The conductive elements current distribution 145 peaks near an antenna feed point 150 of the antenna 45 of the communication device 10. This has the effect of canceling the

magnetic field in the proximity of the one or more shields 90. Without the one or

more impedance blocks such as the first impedance block 125 between the metal display bezel 60 and the printed circuit board 25, the conductive elements current distribution 145 would flow on the display bezel 60 and in effect bring the RF 5 currents closer to the front face ofthe communication device to.

FIG. 5 illustrates an electrostatic discharge current path 155 within the communication device 10 incorporating the present invention. The one or more impedance blocks, such as the first Impedance block 125, provide a low impedance path for DC and ESD frequencies. Ads illustrated, electrostatic discharge currents car 10flow through the display bezel 60, through the first impedance block 125 and down into the other grounded conductive elements of the communication device 10. The created electrostatic discharge current path 155 prevents ESD currents from flowing through and potentially damaging the display 40 and its associated circuitry, an additional benefit of the present invention.

15It will be appreciated by one of orgy skill in the art that the system 115 for enhanced radiation performance can be implemented within various mechanical assembly structures and designs ofthe communication dewce 10 in accordance with Uhe present invention. Multiple combinations of electrical networks and interboard connectors can be used to alter the flow of RF from PC board to PC board or from 20 display bezel to any PC board.

For example, FIG. 6 illustrates a cross section view of the system 115 for enhanced radiation performance implemented within an alternate embodiment of the communication device 10 in accordance with the present invention. Specifically, the

communication device illustrated in FIG. 6 includes a first PC board 160 and a second pc board 165 electrically and mechanically connected using an interboard connector 170. As illustrated, the system 115 functions to provide reduced energy deposition and increased ERP in this alternate embodiment of the communication device 5 similarly to that described previously herein with respect to FIGs. 1 through 5.

As another example, FIG. 7 illustrates a cross section view of the system 115 for enhanced radiation performance implemented within another alternate embodiment of the communication device in accordance with the present invention. Specifically, FIG. 7 illustrates the implementation ofthe system 115 within a communication 10 device 10 having an internal antenna such as a Planar Inverted F Antenna (PIFA) 175 contacting the printed circuit board 25 with a PIFA contact 180 as is widely used in cellular phones. As illustrated, Me system 115 functions to provide reduced energy deposition and increased ERP in this alternate embodiment of the communication device similarly to that described previously herein with respect to FlGs 1 through 6.

15 In accordance with the present invention, the shape ofthe one or more shields 90 can vary depending upon the application and structure of the communication device 10. FIG. 8 illustrates one embodiment of a shield for use within the communication device of FJGs. L through 7 in accordance with the present invention.

Specifically, FIG. 8 illustrates the one or more shields 90 created by painting or 20 depositing material on an inside surface 185 of the front housing 20 ofthe communication device 10. As illustrated, the one or more shields 90 is conformal to the molded plastic front housing 20.

FIG. 9 illustrates further detail of the construction of the one or more shields 90 of FIG. 3 in accordance with the present invention. Dimension 190 adjusts the frequency of the one or more shields 90 in the lower band and its dimensions are substantially similar to a quarter wavelength at the lower band frequency. Dimension 5 195 adjusts the frequency of the one or more shields 90 in the one upper bend and its dunensions are substantially similar to a quarter wavelength at the upper band frequency. Dimension 200 adjusts the frequency of the one or more shields 90 in the other upper band and its dimensions are substantially similar to a quarter wavelength at the other upper band frequency. Dimension 205 adjusts 'the bandwidth o-rqpors.

10 Dimensions 210, 215, 220, and 225 adjust the efficiency of the antenna. It will be appreciated by those of ordinary skill in the art that all the dimensions and features of the one or more shields 90 affect the coefficient of coupling between the shield and the other radio components. Furler, it will be appreciated by those of ordinary skill in the art that the frequency dependent roles of the dimensions can change if the shield 15 shape substantially changes. The frequency bend affected by a certain dimension is wavelength dependent. To optimize radiation perfonnance of a communication device, the dimensions are adjusted in such a way to cause the current distribution to change in a way that lowers the energy deposition of the communication device 10.

Lower energy deposition increases the efficiency of the antenna 45 and unproves the 20 radiated ERP.

As illustrated and in accordance with the present invention, operungs are provided in the one or more shields 90 to allow for the display 40 and the keypad assembly 80. The one or more shields 90 are constructed so that an ohmic path is

provided around the openings, thereby creating a path around the openings for RF currents to flow. The continuity of the one or more shields 90 along the length of the face ofthe connunication dence 10 is necessary to provide this path for the RF currents. 5 FIGs. 10 through 15 illustratevarious alternative embodiments of the one or more shields 90 of FIG. 9 in accordance with the present invention. It will be appreciated by Rose of ordinary skill in the art that other equivalent embodunents are within the scope of the present invention.

In the embodiments of the present invention illustrated in Fins. ' and 5 the 10 one or more shields 90 preferably comprise one dimension substantially similar to a quarter wavelength electrical length which, when placed at a certain distance range, acts as a director of radiated energy. This is due to the currents induced in the one or more shields 90, which produce a total field sponger in the direction away Tom the

user. The currents on the printed circuit board 25 contained within the 15 communication device 10 are presumed stronger on the top and bottom edges while high energy areas are observed close to the anterma feed point 150. When the communication device 10 is placed next to the user (talk mode) the high energy area is projected around the center of the printed circuit board 25. The one or more shields 90, a conductive element, is placed close to the edges of the printed circuit board 25, 20 extending close to the center of the printed circuit board 25, and has one side substantially similar to a quarter of a wavelength. Further, one top comer is placed right above the antenna feed point 150 for maximum current induction. The resultant

"I-shaped" shield is illustrated in FIGs. 9 and 10. In this implementation, an effective shield can be constructed using a minimal amount of material.

The one or more shields 90, in accordance with the present invention, can also substantially cover the display 40 and surrounding area such as that occupied by the 5 display bezel 60 and the display lens 70 of FIG 1. The conductive layer 100 and the dielectric layer 110 of the one or more shields 90 preferably include characteristics designed to give optimum "ERP balance." The dielectric layer 110, for example, can be a thin material with conductivity near 100 Siernens/meter to achieve a low intensity of radio energy on the shielded side of the communication device 10. f.her lessee 10 materials including high permeability and high permittivity substrates can be used to improve the performance of the shield and are anticipated by this invention. lo this configuration the shield further reduces the energy deposition. By proper selection of the conductivity, permeability, and permittivity of the base material, the energy deposition is reduced significantly with only slight degradation on ERP. In this 15 fashion the radiated performance of the communication device achieves the highest ERP for a level of energy deposition.

In the case were the display 40 covers a significant portion of the surface area of the communications dence 10, it may be necessary to extend the one or more shields 90 across the surface of the display 40. In accordance with the present 20 invention, the display 40 and surrounding area of the communication device 10 can be shielded by treating either the display 40 and/or the display lens 70 with conductive transparent film, by treating either or both with sputtered metal, or by adding an intermediate conductive element. The shielding of the display 40 then contacts the

one or more shields 90 located within the front housing 20 and is further isolated from the display bezel 60 for optimal results. Contact can be accomplished using surface to surface contact, a conductive gasket, conductive adhesive, conductive jumpers, a welding process, any combination thereto or an equivalent. For example, the display 5 lens 70 can be ultrasonic-welded to the front housing 20 to create electrical contact.

When shielding of the display 40 is desired, a partial shield over the display area can be utilized with reduced performance improvement. For example, as illustrated in FIG. 16, wires, a wire screen 230, or a partial film can be employed on either the display 40 or the display lens lo increase the light transmission over the one.

10 or more shields 90. Alternatively, the communication device 10 can include a movable element that covers the display 40. This movable element can include conductive material connected to the housing plastics to form the one or more shields 90. FIG. 17 illustrates an alternative embodiment for achieving the conductive element across the display area. As illustrated, Me conductive element can be 15 achieved by using a conductive housing designed so that the front housing 20 is continuous behind the display 40 using any combination of methods described previously. Further, the portion of the front housing 20 located behind the display 40 is preferably isolated from the printed circuit board 25 using one or more impedance blocks as described previously.

20 FIG. 18 illustrates an alternate embodiment for shielding the display 40. As illustrated in FIG. 18, the display 40 can be shielded using a display shield 235 designed to be electrically connected to the conductive housing such as the Wont housing 20 and located behind the display 40. This separate display shield 235 and

the Rant housing 20 can be made conductive using any combination of the methods described previously herein. The electrical connection between Me display shield 235 and the conductive portion of the front housing 20 can further be achieved using any combination of the methods described previously herein.

5 Referring back to FIG. 1, the one or more shields 90 can also include shielding of the keypad assembly 80. The keypad assembly 80 preferably comprises keypad buttons 240 made of conductive material and designed to make electrical contact with the conductive portions of the front housing 20. It will be appreciated by those of ordinary skill in the art that the one or more shields 9Q can be formed using an, 10 combination of the methods described above or an equivalent.

Tlle present invention as describe herein provides a system for reducing energy deposition while increasing ERP performance of a communication device, thereby improving the quality and range of service of the communication device. Although the invention has been described in teIrns of preferred embodiments, it will be 15 obvious to those skilled in the art that various alterations and modifications can be made without departing from the invention. Accordingly, it is intended that all such alterations and modifications be considered as within the spirit and scope of the invention as defined by the appended clanns.

20 What is claimed is:

Claims

1. A communication device comprising: a printed circuit board including: 5 a plurality of components, and a ground plane coupled to the plurality of components for grounding the plurality of components, wherein radio frequency currents and direct currents flow through the ground plane; and a system for enhanced radiation performance of the cotummmeatio.

10 device comprising: one or more shields for directing radio Bequency energy, wherein Me one or more shields are isolated Dom the radio frequency currents on the ground plane, a display bezel, wherein the display bezel is isolated 15 Mom the radio frequency currents on the ground plane using one or more impedance blocks, and the one or more impedance blocks coupled between Me display bezel and the printed circuit board for providing a direct current ground path between the display bezel and the printed circuit board and further for providing the 20 radio frequency isolation between the display bezel and the printed circuit board.

2. A communication device as recited in claim 1 wherein the one or more shields compnse: a conductive layer, and a dielectric layer s

3. A communication device as recited in claim 1 wherein the system for enhanced radiati on performance further composes: a spacer mechanically located between the one or more shields and the Mislay bezel, wherein the spacer adjusts the effects of the one car more sh i rl1on the 10 radiated performance of the communication device by controlling a separation distance between the one or more shields and the display bezel.

4. A communication device as recited in claim 1 wherein the one or more impedance blocks comprise a frequency dependent impedance, wherein adjusting the 15 frequency dependent impedance adjusts the coupling between the display bezel and the printed circuit board for one or more frequency bands.

5. A communication device as recited in clann 1 wherein at least one impedance block of the one or more impedance blocks is coupled between the one or more 20 shields and the printed circuit board, and fiercer wherein the at least one impedance block comprises a frequency dependent impedance, wherein adjusting the frequency dependent unpedance adjusts We coupling between the one or more shields and the printed circuit board for one or more frequency bands.

6. A communication device as recited in claim 1 further comprising: a front housing, wherein the one or more shields are substantially located within the front housing; and 5 a back housing, wherein the one or more shields direct radiated energy away from the front housing and through the back housing.

7. A communication device as recited in claim 1 further comprising: a back housing, wherein the one or more shields are substantial!>' 7r,cated 10 within the back housing; and a front housing, wherein the one or more shields direct radiated energy away from the back housing and through the front housing.

S. A communication device as recited in claim 1 wherein the one or more shields 15 are integrated into one or a combination of elements selected from a group consisting of a front housing, a back housing, a belt clip, a protective case, and a holster.

9. A communication device as recited in claim 1 further comprising: a moveable flip, wherein the one or more shields are located substantially 20 within the moveable flip; and a base, wherein the base remams unshielded, and further wherein the one or more shields direct the radiated energy away Dom the flip and Trough the base.

1 O. A communication device as recited in claim 1 wherein each of the one or more shields comprise a plurality of dimensions, wherein each of the plurality of dimensions adjusts a frequency of each of the one or more shields, and further wherein at least one dimension of the plurality of dimensions adjusts a bandwidth of 5 the frequency response of each of the one or more shields.