System for increasing antenna efficiency

Information

  • Patent Grant
  • 6266019
  • Patent Number
    6,266,019
  • Date Filed
    Friday, July 21, 2000
    24 years ago
  • Date Issued
    Tuesday, July 24, 2001
    23 years ago
Abstract
A communications device having an antenna and a housing having a front section and a rear section, one of the front section and the rear section being conductive. A circuit board is mounted within the housing and includes a point of lowest potential and a perimeter of length P. An electrical connection between the conductive one section and the circuit board point of lowest potential has a length less than one-half P.
Description




BACKGROUND OF THE INVENTION




The present invention is directed toward a communications device, and more particularly toward increasing efficiency of an antenna for a communications device.




A communications device, for example a cellular telephone, typically includes a front section and a rear section, the front and rear sections acting as a housing for a circuit board. The circuit board includes the control circuitry for the cellular telephone. The cellular telephone further includes an antenna coupled to the circuit board used for transmitting and receiving information to and from a cellular base station. Cellular telephones are usually powered by a battery, the negative terminal of which is the lowest point of potential for the cellular telephone. When transmitting information from the cellular telephone to the cellular base station, battery power is consumed and therefore the operational availability of the device is shortened.




In a cellular telephone, one or both of the front and rear sections have in some cases been conductive, that is made of or coated with a conductive material. Where one or both of the sections are conductive, the conductive sections have sometimes been unconnected from the point of lowest potential, and in other cases have been connected to the point of lowest potential via a circuit board trace located around an entire perimeter of the circuit board. When the section(s) are conductive and connected to the point of lowest potential by the perimeter trace, the conductive sections serve as a ground plane for the antenna, aiding in the transmission and reception of information from and to the cellular telephone. However, antenna efficiency is not optimized. A less efficient cellular telephone antenna causes more battery power to be consumed when transmitting information to the cellular base station. Because battery power is limited, it is desirable to increase the efficiency of the antenna.




The present invention is directed to overcoming the problem discussed above.




SUMMARY OF THE INVENTION




In one aspect of the present invention, a communications device having an antenna includes a communication device housing having a front section and a rear section, wherein one of the front section and the rear section is conductive. A circuit board is mounted within the communications device body including a connection with a point of lowest potential for the communications device and having a perimeter of length P. An antenna is connected to the circuit board and is used for transmitting information from and receiving information to the communications device. An electrical connection electrically connects the conductive one of said front and rear sections to the circuit board point of lowest potential, where the electrical connection has a major dimension less than one-half P.




In various forms of this aspect of the invention, the electrical connection is located other than along the perimeter of the circuit board, and may comprise a plurality of contact locations. The electrical connection may be a capacitor or an inductor. The electrical connection may also have a major dimension of length less than one-tenth P. In another form, the antenna is mounted proximate an edge of the circuit board and the circuit board includes a ground plane coupled to the point of lowest potential and the electrical connection is positioned to cause a one-quarter wave waveguide trap to be formed between the one section and the ground plane, the one-quarter wave waveguide trap having a low current point proximate said edge. In another form, the communications device includes a negative power terminal, and the point of lowest potential is an electrical connection with the negative power terminal. In a further form, the electrical connection from the one section and the point of lowest potential is proximate to the negative power terminal.




In another form of this aspect, the one section may be metalized or may be formed from metal. In another form, where the other of the front section and the rear section is conductive, the communications device further comprises a second electrical connection between the other section and the point of lowest potential, where the second electrical connection has a length less than one-half P. In another form of this aspect, the other of the front section and the rear section is conductive, and the communications device further comprises a second electrical connection between the other section and the point of lowest potential substantially along the entire perimeter of the circuit board. In yet another form of this aspect, the other of the front section and the rear section is conductive and electrically unconnected from the point of lowest potential.




In another aspect of the invention, a communications device is provided including a communications device housing having a front section and a rear section, wherein one of the front section and the rear section is conductive. An antenna is mounted to the housing and is used for transmitting information from and receiving information to the communications device. A battery is mounted to the housing for powering the communications device where the battery includes a positive power terminal and a negative power terminal. A circuit board is mounted within the communications device housing and connected to the antenna and to the battery power jet terminals, where the circuit board has a perimeter of length P and includes a circuit board ground plane connected to the negative power terminal. An electrical connection electrically connects the conductive one of the front and rear sections to the circuit board ground plane, where the electrical connection has a major dimension less than ½P.




In various forms of this aspect of the present invention, the electrical connection may comprise a plurality of contact locations, and may be formed by a capacitor or an inductor. The electrical connection further may have a major dimension less than one-tenth P. In another form, the antenna is mounted proximate an edge of the circuit board and the circuit board includes a ground plane coupled to the point of lowest potential, and positioned to cause a one-quarter wave-guide trap to be formed between the one section and the ground plane, the one-quarter wave waveguide trap having a low current point proximate the edge. In another form where the other of the front section and the rear section is conductive, a second electrical connection is located between the other section and the circuit board ground plane, where the second electrical connection has a major dimension less than ½P.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

illustrates a communications device in accordance with the prior art;





FIG. 2

illustrates a communications device embodying the present invention;





FIGS. 3



a


and


3




b


are an exploded side view and side by side sections, respectively, of a communications device in accordance with one embodiment of the present invention;





FIGS. 4



a


and


4




b


are an exploded side view and side by side sections, respectively, of a communications device in accordance with another embodiment of the present invention;





FIGS. 5



a


and


5




b


are an exploded side view and side by side sections, respectively, of a communications device in accordance with still another embodiment of the present invention;





FIGS. 6



a


and


6




b


are an exploded side view and side by side sections, respectively, of a communications device in accordance with yet another embodiment of the present invention;





FIGS. 7



a


and


7




b


are an exploded side view and side by side sections, respectively, of a communications device in accordance with still another embodiment of the present invention;





FIG. 7



c


illustrates the electrical connection utilized in the embodiment of

FIGS. 7



a


and


7




b;







FIG. 8

is an exploded side view of a communications device in accordance with an embodiment of the present invention;





FIG. 9

is an exploded side view of a communications device in accordance with another embodiment of the present invention; and





FIG. 10

is an exploded side view of a communications device in accordance with still another embodiment of the present invention.











DESCRIPTION OF THE PREFERRED EMBODIMENT





FIG. 1

illustrates the electrical connection between a printed circuit board (PCB) and a housing of a mobile terminal such as a cellular telephone


100


in accordance with the prior art. The cellular telephone


100


includes the housing designated by a front section


105


and a rear section


110


, and a PCB


115


. The front section


105


includes an LCD lens


120


and a keypad


125


. An antenna


130


is mounted to the rear section


110


for receiving and transmitting information to and from a cellular base station (not shown). A battery


135


with positive and negative power terminals


136


,


137


respectively is also mounted to the rear section


110


. The PCB


115


is connected to the power terminals


136


,


137


and to the antenna


130


. An LCD


140


is mounted on the PCB


115


, such that when the cellular telephone


100


is assembled, the LCD


140


is viewable through the LCD lens


120


. The PCB further includes a PCB trace


145


located along an entire perimeter P of the PCB


115


, where the PCB trace


145


is connected to a cellular telephone point of lowest potential. Typically, the point of lowest potential is the negative power terminal


137


. Although not shown, the PCB trace


145


may also be exposed on a back side of the PCB


115


.




Where one or both of the front and rear sections


105


and


110


are conductive, the conductive section(s) have sometimes been unconnected from the point of lowest potential, and in other cases have been connected to the point of lowest potential along the entire perimeter P of the PCB


115


via the PCB trace


145


. Where the conductive section(s) are connected to the point of lowest potential, the electrical connections are typically made using a conductive caulk, a conductive elastomer, or a conductive gasket along a perimeter of the respective front and rear section. When the cellular telephone


100


is assembled, the electrical connection connects the respective conductive section to the point of lowest potential along the entire perimeter P of the PCB


115


via the PCB trace


145


.





FIG. 2

illustrates a communications device embodying the present invention. Components of

FIG. 2

identified by reference numerals identical to those of

FIG. 1

are the same and will not be discussed in detail.




In one form of the

FIG. 2

embodiment, the front section


105


is conductive, that is formed from metal, formed from a conductive material such as a conductive plastic, or coated with a conductive material along an inner surface of the front section


105


. The front section


105


is unconnected from the point of lowest potential, for example the negative battery terminal


137


or some terminal connected thereto, except for an electrical connection between positions designated as


205




a


and


205




b,


where


205




b


is further connected to the point of lowest potential


137


.




In another form of the

FIG. 2

embodiment, where the front section


105


is conductive, the front section


105


is unconnected from the point of lowest potential


137


except for an electrical connection between an entire side


210




a


of the front section


105


designated by area


210




a


and a side of the PCB


115


along, for example, the portion of the PCB trace


145


designated within the area


210




b.






In yet another form, where the front section


105


is conductive, the front section


105


is unconnected from the point of lowest potential


137


except for two (2) electrical connections coupling the front section


105


to the point of lowest potential


137


. For example, electrical connections extending between positions


215




a


and


215




b


and positions


220




a


and


220




b


electrically couple the front section


105


to the point of lowest potential


137


, where the electrical connections


215




b


and


220




b


are connected to the point of lowest potential


137


.




In other forms the rear section


110


is conductive, and is unconnected from the point of lowest potential except for an electrical connection between a position


225




a


located on a back of the PCB


115


, and a position


225




b,


where the position


225




a


is connected to the point of lowest potential


137


.




In additional forms (not shown), both the front and rear sections


105


and


110


are conductive and one of the front and rear sections is connected to the point of lowest potential


137


with the electrical connection having a major dimension less than ½P. The other of the front and rear sections is coupled to the point of lowest potential by a second electrical connection having a major dimension less then ½P, or via an electrical connection around the entire perimeter P of the circuit board via the PCB trace


145


.




For the embodiments just described, the electrical connection from the respective conductive section to the point of lowest potential, having a major dimension less than one-half the perimeter of the PCB


115


, increases the antenna efficiency of the antenna


130


. Increasing antenna efficiency allows the cellular telephone to transmit a signal having the same strength as a cellular telephone utilizing prior art electrical connection techniques between the conductive section(s) and the point of lowest potential, while consuming less battery power. Alternatively, the electrical connections utilized in the embodiment just described allow a greater signal strength to be transmitted from the cellular telephone over that of the prior art, while consuming the same battery power as the cellular telephone utilizing prior art electrical connections between the conductive section(s) and the point of lowest potential.




The electrical connections may be formed using wire, conductive foam, conductive elastomer, conductive gasket material, or any other material sufficient for forming an adequate electrical ground.




The size of the electrical connection is not vital so long as it is sufficient (large enough) to form an adequate ground, and has a major dimension less than one-halfP. A minimum size for an electrical connection to form an adequate electrical ground is known to one skilled in the art. A typical thickness for the electrical connection ranges from a width of a wire, or conductive sheet of approximately 1 mm width, to a width of a circular bead of conductive material (for example conductive foam or gasket) of approximately 6 mm diameter. The width of the electrical connection may be less so long as an adequate electrical ground is formed, and the width may be greater where placement of components in the communications device or other manufacturing considerations allow. The height of the electrical connection is typically that of a distance between the respective positions between which the electrical connection is made when the front section


105


, the rear section


110


and the PCB


115


are assembled together. One skilled in the art will realize that the height of the electrical connection may be greater, especially for example, where the electrical connection is formed from a compressible material such as a conductive foam or gasket, or from a conductive material having spring-like properties. In addition, the electrical connection may be formed using an inductor or a capacitor, further discussed below.




When determining the position for the electrical connection between the respective conductive section and the point of lowest potential, it is preferable to select a position proximate the negative battery terminal


137


. However, due to manufacturing considerations or placement of certain components on the respective conductive section or the PCB, the preferred position may not always be achieved. For example, if it is desired to connect a conductive front section


105


to the point of lowest potential, and the negative battery terminal


137


is positioned directly beneath the LCD


140


and the LCD lens


120


, a connection between the front section


105


and the PCB


115


could not be achieved directly above the negative battery terminal


137


. In such situations, the position of the electrical connection is selected such that the point of contact between the front section


105


and the PCB


115


are close to but not directly above the negative battery terminal


137


.




Although it is preferable that the electrical connection be proximate the negative battery terminal, improved antenna performance is also achieved where the electrical connection is not proximate the negative battery terminal.





FIGS. 3



a


and


3




b


are exploded side and side by side section views, respectively, of an Ericsson cellular telephone


300


, model #A1228d, in accordance with an embodiment of the present invention. A front section


305


, a rear section


310


, and a PCB


315


are shown. The PCB


315


includes a PCB trace


317


exposed on a front and a back of the PCB


315


along the perimeter of the PCB. The PCB trace


317


is connected to a PCB ground plane


318


which is connected to the point of lowest potential for the cellular telephone, typically a negative power terminal


319


of a battery


320


. The PCB


315


further includes a shield can


321


which is connected to the PCB ground plane


318


. The shield can is conductive, and is typically used for electrostatic discharge protection, and/or to reduce emissions from the cellular telephone. The PCB is connected to an antenna


322


, used for receiving and transmitting information to and from the cellular telephone. Both the front and rear section


305


and


310


are metalized, that is coated with a conductive material. The rear section


310


is connected to the PCB ground plane around an entire perimeter P of the PCB


315


via the PCB trace


317


. The front section


305


is isolated from the PCB ground plane except for an electrical connection


335


which extends between a position


340




a


on the front section


305


, and a position


340




b


located on the shield can


321


. Positions


340




a


and


340




b


are located approximately 21 mm from a top of the cellular telephone


300


, designated generally by arrow


350


, and approximately 11 mm from a left side of the cellular telephone


300


, designated generally by an arrow


355


. The electrical connection


335


is formed from a conductive elastomer having a substantially circular configuration of approximately 3 mm diameter. The elastomer is of sufficient height such that when the PCB


315


is assembled within the front section


305


, the electrical connection


335


contacts both the front section


305


and the shield can


320


. Electrically connecting the front section


305


to the point of lowest potential in this manner improves antenna efficiency of the antenna


322


by approximately 65%.





FIGS. 4



a


and


4




b


are exploded side and side by side views, respectively, of an Ericsson cellular telephone


400


, model #T28s, in accordance with another embodiment of the present invention. A front section


405


, a rear section


410


, and a PCB


415


are shown. The PCB


415


includes a PCB trace


417


exposed on a front and a back of the PCB


415


along the perimeter of the PCB. The PCB trace


417


is connected to a PCB ground plane


418


which is connected to the point of lowest potential for the cellular telephone, typically a negative power terminal


419


of a battery


420


. The PCB


415


is electrically connected to an antenna


422


. Both the front and rear sections


405


and


410


are conductive, where the front section


405


is metalized, and the rear section


410


is made of metal. The rear section


410


is connected to the PCB ground plane


418


around the entire perimeter P of the PCB


415


via the PCB trace


417


. The front section


405


is isolated from the PCB ground plane except for an electrical connection


435


which extends between a position


440




a


on the front section


405


, and a position


440




b


located on the PCB


415


. The positions


440




a


and


440




b


are located approximately 20 mm from a top of the cellular telephone


400


designated generally by an arrow


450


, and approximately 24 mm from a right side of the cellular telephone designated generally by an arrow


457


. The electrical connection


435


is formed from an inductor. The inductor may have from 2 to 6 turns, such as 3.5 to 4 turns. The inductor has an air core with a diameter of approximately 4 mm. Electrically connecting the front section


405


to the point of lowest potential


419


in this manner improves antenna efficiency of the antenna


422


by approximately 65%.





FIGS. 5



a


and


5




b


are exploded side and side by side views, respectively, of an Ericsson cellular telephone


500


, model #KH668, in accordance with an embodiment of the present invention. A front section


505


, a rear section


510


, and a PCB


515


are shown. The PCB


515


includes a PCB trace


517


exposed on a front and a back of the PCB


515


along a perimeter of the PCB. The PCB trace


517


is connected to a PCB ground plane


518


which is coupled to the point of lowest potential for the cellular telephone


500


, typically a negative power terminal


519


of a battery


520


. The PCB


515


is electrically connected to an antenna


522


. The front section


505


is metalized, and the rear section


510


is made of metal. The rear section


510


is connected to the PCB point of lowest potential around the entire perimeter P of the PCB


515


via PCB trace


517


. The front section


505


is isolated from the PCB point of lowest potential except for two electrical connections


535


and


537


. One electrical connection


535


extends between a position


535




a


located on the front section


505


and a position


535




b


which is located on the front of the PCB


515


. The other electrical connection


537


extends between a position


537




a


located on the front section


505


and a position


537




b


located on the front of the PCB


515


. The positions


535




b


and


537




b


are coupled to the point of lowest potential for the cellular telephone


500


, for example, via the PCB trace


517


. Positions


535




a


and


535




b


are located approximately 6 mm from a left side of the cellular telephone


500


designated generally by an arrow


555


, and approximately 6 mm from a bottom of the cellular telephone designated generally by an arrow


559


. Positions


537




a


and


537




b


are located approximately 6 mm from a right side of the cellular telephone


500


designated generally by an arrow


557


, and approximately 6 mm from the bottom designated at


559


. Here, the electrical connections


535


and


537


are formed from respective screw bosses approximately 5 mm in diameter, which electrically connect the front section


505


to the PCB


515


when the front section and the PCB are assembled. Electrically connecting the front section


505


to the point of lowest potential


519


in this manner improves antenna efficiency of the antenna


522


by approximately 20%.




In the embodiments discussed above, it is common that a conductive section is connected to the point of lowest potential via an electrical connection having a length less than one-half the perimeter of the PCB, or is completely unconnected from the point of lowest potential. In such circumstances, it may be necessary to remove a portion of the metalized coating on the conductive section, or to insulate a portion of the conductive section from the point of lowest potential to ensure that a complete contact between the respective conductive section and the point of lowest potential is not made. For example, referring to

FIG. 5



a,


a portion around a perimeter of the front section


505


, designated in the area


570


, is not metalized with the rest of the front section


505


, to ensure that when the PCB


515


is assembled with the front section


505


, the front section


505


is not connected to the point of lowest potential along the entire perimeter of the front section


505


via the PCB trace


517


. Alternatively, the entire front section


505


may be metalized, with an insulating material placed around the perimeter of the front section


505


to ensure that the front section


505


does not contact the point, of lowest potential around the entire perimeter of the front section via the PCB trace


517


.





FIGS. 6



a


and


6




b


are exploded side and side by side views, respectively, of an Ericsson cellular telephone


600


, model #A2218d, in accordance with another embodiment of the present invention. A front section


605


, a rear section


610


, and a PCB


615


are shown. The PCB


615


includes a PCB trace


617


exposed on a front and a back of the PCB


615


extending along a perimeter of the PCB. The PCB trace


617


is connected to a PCB ground plane


618


which is coupled to a point of lowest potential for the cellular telephone


600


, typically a negative power terminal


619


of a battery


620


. A shield can


621


is formed from metalized plastic and is coupled to the back of the PCB


615


via the PCB trace


617


. The PCB


615


is further coupled to an antenna


622


. The front section


605


is metalized, and the rear section


610


is made of plastic. The shield can


621


is connected to the point of lowest potential around the entire perimeter P of the PCB


615


via the PCB trace


617


. The front section


605


is unconnected from the point of lowest potential except for an electrical connection


635


which extends between a position


635




a


on the front section


605


, and a position


635




b


located on the front and side of the PCB


615


. The electrical connection


635


and the corresponding position


635




a


and


635




b


are located along a left side of the cellular telephone


600


, generally designated by an arrow


655


, approximately 77 mm from a top of the cellular telephone, generally designated by an arrow


650


. The electrical connection


635


is formed from a conductive elastomer of approximately 4 mm width and 5 mm length, such that when the front section


605


and the PCB


615


are assembled, the front section


605


is coupled to the point of lowest potential. Electrically connecting the front section


605


to the point of lowest potential


625


in this manner improves antenna efficiency by approximately 50%.




In an alternate embodiment (not shown), the electrical connection


635


and respective positions


635




a


and


635




b


are located on a right side of the cellular telephone


600


approximately 77 mm from the top


650


.





FIGS. 7



a


and


7




b


are exploded side and side by side views, respectively, of an Ericsson cellular telephone


700


, model #KF788, according to another embodiment of the present invention. A front section


705


, a rear section


710


and a PCB


715


are shown. The PCB


715


includes a PCB ground plane


718


which is connected to the point of lowest potential for the cellular telephone


700


, typically a negative power terminal


719


of a battery


720


. The PCB


715


further includes a shield can


721


which is coupled to the PCB ground plane. The PCB


715


is electrically connected to an antenna


722


. Both the front and rear sections


705


and


710


are metalized. The front section


705


is isolated from the point of lowest potential. The rear section


710


is isolated from the point of lowest potential except for an electrical connection


735


extending between a position


735




a


located on the shield can


721


, and a position


735




b


located on the rear section


710


. The positions


735




a


and


735




b


are located approximately 41 mm from a top of the cellular telephone


700


designated generally by an arrow


750


, and approximately 1 mm from a right side of the cellular telephone


700


designated generally by an arrow


757


.





FIG. 7



c


further illustrates the electrical connection


735


, which may be formed from a sheet of metal bent in a “J” configuration. The electrical connection


735


has a height of approximately 5 mm, a length of approximately 12 mm, and a curved portion designated generally at


760


having a diameter of approximately 2 mm. In an alternate embodiment, the length of the electrical connection


735


may be approximately 1 cm.




A bottom portion


760


of the electrical connection


735


is installed in a battery clip for the negative power terminal


719


and makes contact with metalized rear housing


710


, and a top portion of the electrical connector


735


designated at the curved section


765


makes contact with the shield can


721


. Electrically connecting the rear section


710


to the point of lowest potential in this manner improves antenna efficiency by approximately 40%.




In at least the embodiments discussed above where the front section is coupled to the point of lowest potential via an electrical connection having a length less than one-half the perimeter of the PCB, it is believed that the electrical connection between the front section and the PCB causes a quarter wave, wave guide trap to be formed between the front section and the PCB, as described with respect to

FIGS. 8-10

.





FIGS. 8-10

are exploded side views of a cellular telephone in accordance with embodiments of the present invention.

FIGS. 8-10

show a front section


805


, a rear section


810


, and a PCB


815


. The PCB


815


includes a ground plane


818


which is connected to the cellular telephone


800


point of lowest potential, typically a negative power terminal (not shown) of a battery


820


. The PCB further includes a PCB trace (not shown) exposed on a front and a back of the PCB, similar to the PCB traces of

FIGS. 3



b,




4




b,




5




b


and


6




b


extending around a complete perimeter of the PCB, and connected to the PCB ground plane


818


. The rear section


810


is connected to the PCB


815


around the entire perimeter P of the PCB


815


via the PCB trace. An antenna


822


is coupled to the PCB


815


used for receiving and transmitting information to/from the cellular telephone.




In

FIG. 8

, an electrical connection


825


is formed between position


825




a


on the front section


805


and position


825




b


located on the PCB


815


. Position


825




b


is further coupled to the PCB ground plane


818


. The electrical connection is positioned approximately λ/4 from a top of the front section


805


and PCB


815


such that a quarter wave, wave guide trap is formed between the front section and the PCB


815


, with a low current point (or high impedance Z) near the antenna


822


. This presents a very high impedance to the normal current path down the front of the telephone, causing the ground currents i


t


to flow down the rear section


810


of the cellular telephone as designated by an arrow


830


. The ground currents i


t


are not restricted from flowing down the sides and the rear section of the cellular telephone


800


, so a necessary antenna ground plane for the antenna


822


may be realized within the cellular telephone


800


. The length of the quarter wave trap will be somewhat shorter than a free space quarter wave length due to dielectric loading between the conductive front section


805


and conductive rear section


810


and PCB


815


. The connection


825


in

FIG. 8

may be formed from a wire, or a conductive elastomer or gasket as discussed above.





FIG. 9

illustrates use of inductive loading to significantly shorten the length of the quarter-wave wave guide trap between the front section


805


and the PCB


815


. Here, the electrical connection


840


is an inductor providing inductive loading. The inductive loading provided by the inductor


840


is advantageous as it is not always possible to locate the electrical connection between the front section


805


and the PCB


815


at the λ/4 distance from the top of the front section


805


and PCB


815


because of, for example, location of a cellular telephone LCD or a cellular telephone keypad, or due to other manufacturing considerations.





FIG. 10

illustrates utilization of capacitive loading to shorten the length of the quarter wave, wave guide trap. Shortening the length of the quarter wave wave-guide trap using a capacitor is advantageous as it is not always possible to locate the electrical connection between the front section


805


and the PCB


815


at the λ/4 distance because of components on the front section


805


and PCB


815


, or because of other manufacturing considerations. Here, the electrical connection includes an electrical connection


845




a


similar to the electrical connection


825


discussed above with respect to FIG.


8


and an electrical connection


845




b


formed by a capacitor. The value of the capacitor and position of both the electrical connections


845




a


and


845




b


may be determined experimentally to achieve the advantages of the present invention, as would be realized by one skilled in the art.




Although the present invention has been discussed in the context of a cellular telephone, one skilled in the art would realize that the advantages gained therefrom would be realized in any communications device.




Still other aspects and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the advantages of the present invention and preferred embodiments as described above would be obtained.



Claims
  • 1. A communications device, comprising:a communications device housing having a front section and a rear section, wherein one of the front section and the rear section is conductive; an antenna for transmitting information from and receiving information to the communications device; a circuit board mounted within the communications device housing, where the circuit board has a perimeter of length P, is electrically connected to the antenna, and includes a point of lowest potential for the communications device; and an electrical connection electrically connecting said conductive one of said front and rear sections to said circuit board point of lowest potential, said electrical connection having a major dimension less than ½P.
  • 2. The communications device of claim 1 wherein the electrical connection is located other than along the perimeter of the circuit board.
  • 3. The communications device of claim 1 wherein the electrical connection comprises a plurality of contact locations.
  • 4. The communications device of claim 1 wherein the antenna is mounted proximate an edge of the circuit board and the circuit board includes a ground plane coupled to the point of lowest potential, and the electrical connection is positioned to cause a ¼ wave waveguide trap to be formed between said conductive one of said front and rear sections and the ground plane, the ¼ wave waveguide trap having a low current point proximate said edge.
  • 5. The communications device of claim 1 wherein the electrical connection is an inductor.
  • 6. The communications device of claim 1 wherein the communications device includes a negative power terminal, and the point of lowest potential is the negative power terminal.
  • 7. The communications device of claim 6 wherein the electrical connection from said conductive one of said front and rear sections and the point of lowest potential is proximate to the negative power terminal.
  • 8. The communications device of claim 1 wherein the communications device is a cellular telephone.
  • 9. The communications device of claim 1 wherein the electrical connection has a major dimension less than one-tenth P.
  • 10. The communications device of claim 1 wherein said conductive one of said front and rear sections includes a metalized coating deposited thereon.
  • 11. The communications device of claim 1 wherein said conductive one of said front and rear sections is metal.
  • 12. The communications device of claim 1 wherein the electrical connection is a capacitor.
  • 13. The communications device of claim 1 wherein the other of the front section and the rear section is conductive, and further comprising a second electrical connection between said other section and said point of lowest potential, said second electrical connection having a length less than ½P.
  • 14. The communications device of claim 1 wherein the other of the front section and the rear section is conductive, and further comprising a second electrical connection between said other section and said point of lowest potential substantially along the entire perimeter of the circuit board.
  • 15. The communications device of claim 1 wherein the other of the front section and the rear section is conductive but not connected to the point of lowest potential.
  • 16. A communications device, comprising:a communications device housing having a front section and rear section, wherein one of the front section and the rear section is conductive; an antenna mounted to the housing for transmitting information from and receiving information to the communications device; a battery mounted to the housing for powering the communications device and including a positive power terminal and a negative power terminal; a circuit board mounted within the communications device housing and connected to the antenna and to the battery power terminals, the circuit board having a perimeter of length P and including a circuit board ground plane connected to the negative power terminal; and an electrical connection electrically connecting said conductive one of the front and rear sections to the circuit board ground plane, said electrical connection having a major dimension less than ½P.
  • 17. The communications device of claim 16 wherein the electrical connection comprises a plurality of contact locations.
  • 18. The communications device of claim 16 wherein the antenna is mounted proximate an edge of the circuit board and the circuit board includes a ground plane coupled to the point of lowest potential, and positioned to cause a ¼ wave wave-guide trap to be formed between said one section and the ground plane, the ¼ wave waveguide trap having a low current point proximate said edge.
  • 19. The communications device of claim 16 wherein the electrical connection is an inductor.
  • 20. The communications device of claim 16 wherein the electrical connection is a capacitor.
  • 21. The communications device of claim 16 wherein the other of the front section and the rear section is conductive, and further comprising a second electrical connection between said other section and said circuit board ground plane, said second electrical connection having a major dimension less than ½P.
  • 22. The communications device of claim 16 wherein the electrical connection has a major dimension less than one-tenth P.
US Referenced Citations (3)
Number Name Date Kind
5020136 Patsiokas et al. May 1991
5606733 Kanayama et al. Feb 1997
5977917 Hirose Nov 1999