Patent Abstract:
An antenna configuration for a mobile communication device. The antenna configuration includes at least a first antenna configured so that the first antenna may be mounted near or between a speaker and a earpiece of a mobile station. In an embodiment of the invention, the first antenna comprises a substantially flat conductor including at least one hole for passing sound from the speaker to the earpiece of the mobile station. The first antenna is configured to receive GPS signals. A second antenna is implemented on the mobile station to transmit and receive cellular transmissions.

Full Description:
FIELD OF THE INVENTION 
     This invention relates generally to antennas and, more particularly, to compact, lightweight antennas for mobile communications devices. 
     BACKGROUND OF THE INVENTION 
     As mobile telephone technology has advanced, the phone developers have concentrated on making the phone smaller so that more volume and weight could be set aside for battery storage, while keeping the overall form-factor of the phone to be pocket-sized. With the advent of new long-life battery storage technologies and low power digital modulation, the phone has been reduced to a size and battery life that is more than adequate in both departments. Now that these problems are effectively solved, an interest to adding new features to the phone beyond ordinary telecommunications has developed. Among these features is the accurate locating technology afforded by GPS receivers. 
     Adding a GPS receiver to a mobile phone permits dual use of many of the phone&#39;s current parts: embedded CPU, DSP, battery, user interface. Unfortunately, cellular downlink signals are different enough from GPS downlink that an entirely different antenna and filtering arrangement may be needed. For example, GPS downlink signals are typically circularly polarized, whereas cellular signals are not. Moreover, since dual antennas are needed, each antenna must be oriented so that while the mobile phone is positioned for each specialized use, as few phone parts and external obstacles are interposed between the external radio source and the phone antenna. 
     Since a mobile station such as a mobile phone must be highly miniaturized in order to provide its current functionality, designers adding new features must use as little real estate on the main circuit board as possible. Current generation circular polarized patch antennas, as described, for example, in the paper, “Compact Microstrip Antenna Loaded with Very High Permittivity Superstrate”, Chih-Yu Huang and Jian-Yi Wu, IEEE Antennas and Propagation Society International Symposium 1998, Jun. 21-26 1998, Atlanta Ga., may occupy as little as a square 20 mm on a side. This type of antenna, and others that lack holes are continuous conductor type antennas. Because GPS depends on line-of-sight (LOS) operation between the satellite(s) and the receiver, the GPS receive antenna must be on the top of the mobile station while employed for its locating function—which means for purposes of human-readable output, the mobile station&#39;s display must be situated on the same side as the antenna. Furthermore, the GPS antenna must be on the distant end, as opposed to the end that is grasped. Moreover, on that same side, the antenna competes for space with display, keyboard, microphone and speaker as principal front-side mobile phone components. 
     Deploying the GPS antenna on a flip or a boom causes its own problems. A flip requires extra enclosing hardware, as well as a resilient path for conductors to carry signals between the flip and the main phone. More parts thus produce higher cost, greater weight, lower reliability among other problems. The same problems apply to any other component that is deployed on a flip or boom. 
     OBJECTS OF THE INVENTION 
     It is therefore an object of this invention to provide an improved antenna for a mobile communications device that overcomes the foregoing and other problems. 
     Another object and advantage of this invention is to provide an auxiliary antenna for a mobile communications device that may be configured and hidden within the device while not disturbing significantly the functions of a basic cellular antenna. 
     It is a further object and advantage of this invention to provide an antenna that is transparent to sound so that sound devices may operate near the ground-plane of the antenna. 
     It is a further object and advantage of this invention to provide an antenna that can be situated between a speaker and a user&#39;s ear without changing the typical speaker location on the upper longitudinal middle of the front side of the phone. 
     It is a further object to provide an elliptically polarized antenna operating close to a non-polarized antenna such that both may be housed in a common enclosure. 
     SUMMARY OF THE INVENTION 
     The present invention provides a antenna that is compatible with the form of portable mobile devices. The antenna configuration includes a conducting portion that is flat and generally rectangularly shaped. The antenna maybe configured so the conducting portion of the antenna configuration may be mounted within a mobile station between a speaker and an earpiece. Slots may be implemented in each side to permit the conducting portion to operate like a microstrip antenna having dimensions much larger, but still with high levels of gain with respect to the desired frequencies. At least one hole may be implemented in the conducting portion to aid in sound transmission from the speaker to the earpiece. The implementation of a hole in the approximate center of the conducting portion has virtually no effect in the gain of the antenna since the central region for a continuous antenna having a rectangular shape (or with slots) is a voltage minimum. 
     In an embodiment of the invention, a mobile phone is provided a flat GPS antenna which has a hole through the central region. The hole is located just above a speaker or other input/output device, wherein the speaker is mounted on a printed circuit board (PCB), and the GPS antenna is set-off from the PCB, yet still enclosed within a case or casing of the mobile phone. The case has an earpiece which has holes located near to the GPS antenna hole. A cellular antenna is mounted below the PCB to permit reception and transmission of cellular frequencies. The GPS antenna, speaker, and cellular antenna are located on the part of the mobile phone that is the distant end, i.e. the remaining part of the mobile phone is for grasping and other handling by a person. In alternative embodiments, the cellular antenna may be any other type of antenna usually for cellular communications such as extendable, stub antennas or antennas embedded in flip portions of a mobile station. 
     Similar performance with a two-feed circularly polarized microstrip antenna can be achieved, while making the size of the two-feed antenna as small as the size of the single-feed arrangement. It is also quite common to generate elliptical polarization by using two feed points to excite two orthogonal modes on the patch with a 90 degrees phase difference between their excitations. 
     In another embodiment of the invention, the antenna generates elliptical polarization by using two blunt opposite corners of the patch. The placement of the feedpoint at the end of a slot is needed to provide the elliptical polarization. Enhanced performance occurs by putting a high permittivity superstrate over the patch as well as between the patch and the ground plane. The longest dimension is about 20 mm, which appears electrically as a half wavelength (about 9.5 cm for 1575 MHz GPS signals). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a elevation side cut away view of mobile station including a dual antenna configuration, according to an embodiment of the invention. 
     FIG. 2 is a elevation side view of a dual antenna configuration, according to an alternate embodiment of the invention. 
     FIG. 3 a  is a top view of a GPS antenna configuration, according to an embodiment of the invention. 
     FIG. 3 b  is an elevation view of a the GPS antenna of FIG. 3 a.    
     FIG. 4 a  is a perspective view of a GPS antenna configuration according to an alternate embodiment of the invention. 
     FIG. 4 b  is an elevation side view of the antenna configuration of FIG. 4 a.    
     FIG. 5 a  is a perspective view of GPS antenna configuration according to an alternate embodiment of the invention. 
     FIG. 5 b  is an elevation side view of the antenna configuration of FIG. 5 a.    
     FIG. 6 a  is a perspective view of a mobile phone including an antenna configuration according to an alternate embodiment of the invention. 
     FIG. 6 b  is an elevation side view of the antenna configuration of FIG. 6 a.    
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a elevation view of a dual antenna configuration  100  according to an embodiment of the invention. The main supporting surface is the printed circuit board  101 , which provides a ground plane on at least one side of the board. A radio transmit and receive patch antenna  103  such as U.S. patent application filed Jan. 19, 1998, appl. Ser. No. 09/005,103, is located on the back of the board, which affords the antenna fewer obstructions when an ear is placed close to the front side of the board. The front of the PCB  101  includes a sound transducer  105  which, for example, may be a speaker,  105  which is to located under a elliptically polarized GPS antenna  107 . The GPS antenna  107  provides a conductor hole  109  through which sound passes. Conductor hole  109  may be square, rectangular round or any other shape. Either side of the PCB  101  can operate as a ground plane. Both antennas are mounted on the distant end  131  of the PCB  101 , while the grasping end  133  may be mounted within portions of a mobile device used for handling, for example, by a hand. Surrounding the entire unit is a mobile phone exterior case  141  or casing which includes an earpiece  143  having at least one sound hole  145 . 
     GPS ellipticaly polarized antenna  107  further includes a dielectric superstrate  121  having a superstrate hole  109   a  positioned above conductor hole  109   b  of the substantially flat conductor  110 . In addition, below the conductor is the high permittivity dielectric substrate  125  and a substrate hole  109   c  as well as a feed hole  129 , which provides a conduit through which feed probe  151  passes. Holes  109 ,  109   a ,  109   b ,  109   c , may be square, rectangular, round or any other shape. 
     Both the substrate  125  and the superstrate  121  overlap all parts of conductor  110  and extend beyond the outer edges of conductor  110 . The substrate  125  and the superstrate  121  may come in contact with each other. 
     FIG. 2 shows an alternative embodiment wherein the PCB  201  has a PCB hole  202  with a speaker  205  mounted facing the hole, but on the back side of the PCB  201 . Transmit and receive antenna  203  is below the PCB  201 . 
     FIG. 3 a  shows the general configuration of a GPS antenna conductor  300  according to the invention. Antenna conductor  300  may be used in place of antenna conductor  100  of FIG.  1  and FIG.  2 . All angles may be approximately 90° unless otherwise specified. The antenna conductor is generally rectangular, having sides  301 ,  302 ,  303 ,  304 . In each side are slots  311 ,  312 ,  313 ,  314 , having a slot width  318  and a slot length  319 . Each slot may be centered on either a horizontal center line  321  or a vertical center line  322 . Opposing corners have edges  323 ,  324 , each with a blunt length  325 . The edge may be at approximately 45° angle to the sides. Centered on both center lines is conductor hole  350  having a square shape. The sides of the conductor hole  350  are approximately parallel to the sides of the antenna patch. All corners may be rounded due to manufacturing tolerances by radiuses up to 5% of the shortest side next to a corner. 
     Above and below conductor  300  is a superstrate and a substrate, each having a minimal amount of overlap, which may be better seen referring to FIG. 3 b.  Superstrate perimeter  370  overlaps conductor  300 . Superstrate has a hole  371  that has a area at the top of the superstrate. The hole  371  may conform to the dimensions of the conductor hole  350 , or the hole  371  may be smaller in width than the conductor hole  350 . 
     Substrate  390  has a hole  372  that has a area at the top of the substrate. The hole  372  may conform to the dimensions of the conductor hole  350 , or the hole  372  may be smaller in width than the conductor hole  350 . Multiple holes through the substrate  390  and superstrate  370  can substitute for a single hole, so long as all the holes line up and together allow significant sound to pass through. In addition, each of the substrate and superstrate holes must have at least one end at the main conductor hole  350 . 
     In addition, substrate has a feed hole  380  through which a conductor or feed probe may pass. Feed hole  380  ends at feedpoint  381  on the underside of the antenna. Feedpoint  381  is centered on horizontal centerline  321 , but may function just as well on the vertical centerline  322 . The choice of centerlines, and location on either side of the conductor hole is not important since a mirror image of the antenna operates just the same as the opposite orientation, except that the mirror image antenna receives left-hand circular polarized signals. However, in the case where the invention must handle GPS signals, which are right-hand circular polarized, only the orientation as appears in FIG. 3 will properly receive such signals. All holes, whether in the substrate or the superstrate pass in an orthogonal direction in relation to the PCB. A GPS signal carrying conductor attaches by means known in the art to couple the antenna conductor via the feedpoint  381  to filter or amplifier circuitry located on or below the ground plane. 
     FIG. 4 a  shows the general configuration of a GPS antenna conductor  400  according to the invention. Antenna conductor  400  may be used in place of antenna conductor  100  of FIG.  1  and FIG.  2 . All angles may be approximately 90° unless otherwise specified. The antenna conductor is generally rectangular, having sides  401 ,  402 ,  403 ,  404 . In each side are slots  411 ,  412 ,  413 ,  414 , having a slot width  418  and a slot length  419 . Each slot may be centered on either a horizontal center line  421  or a vertical center line  422 . Centered on both center lines is conductor hole  450  having a square shape. The sides of the conductor hole  450  are approximately parallel to the sides of the antenna patch. All corners may be rounded due to manufacturing. 
     Above and below conductor  400  is a superstrate and a substrate, each having a minimal amount of overlap, which may be better seen referring to FIG. 4 b.  Superstrate perimeter  470  overlaps conductor  400 . Superstrate has a hole  471  that has a area at the top of the superstrate. The hole  471  may conform to the dimensions of the conducto r hole  450 , or the hole  471  may be smaller in width than the conductor hole  450 . 
     Substrate  490  has a hole  472  that has a area at the top of the substrate. The hole  472  may conform to the dimensions of the conductor hole  450 , or the hole  472  may be smaller in width than the conductor hole  450 . Multiple holes through the substrate  490  and superstrate  470  can substitute for a single hole, so long as all the holes line up and together allow significant sound to pass through. In addition, each of the substrate and superstrate holes must have at least one end at the main conductor hole  450 . 
     In addition, substrate has a first feed hole  480  through which a first conductor or feed probe may pass. First feed hole  480  ends at feedpoint  481  on the underside of the antenna. Feedpoint  481  is centered on horizontal centerline  421 . All holes, whether in the substrate or the superstrate pass in an orthogonal direction in relation to the PCB. A GPS signal carrying conductor attaches by means known in the art to couple the antenna conductor via the feedpoint  481  to filter or amplifier circuitry located on or below the ground plane. 
     In addition, substrate has a second feed hole  485  through which a second conductor or feed probe may pass. Second feed hole  485  ends at feedpoint  486  on the underside of the antenna. Feedpoint  486  is centered on vertical centerline  422 . All holes, whether in the substrate or the superstrate pass in an orthogonal direction in relation to the PCB. A GPS signal carrying conductor attaches by means known in the art to couple the second antenna conductor via the feedpoint  486  to filter or amplifier circuitry located on or below the ground plane. 
     FIG. 5 a  shows the general configuration of a GPS antenna conductor  500  according to the invention. Antenna conductor  500  may be used in place of antenna conductor  100  of FIG.  1  and FIG.  2 . All angles may be approximately 90° unless otherwise specified. The antenna conductor is generally rectangular, having sides  501 ,  502 ,  503 ,  504 . In each side are slots  511 ,  512 ,  513 ,  514 , having a slot width  518  and a slot length  519 . Each slot may be centered on either a horizontal center line  521  or a vertical center line  522 . Centered on both center lines is conductor hole  550  having a square shape. The sides of the conductor hole  550  are approximately parallel to the sides of the antenna patch. All corners may be rounded due to manufacturing. 
     Above and below conductor  500  is a superstrate and a substrate, each having a minimal amount of overlap, which may be better seen referring to FIG. 5 b.  Superstrate perimeter  570  overlaps conductor  500 . Superstrate has a hole  571  that has a area at the top of the superstrate. The hole  571  may conform to the dimensions of the conductor hole  550 , or the hole  571  may be smaller in width than the conductor hole  550 . 
     Substrate  590  has a hole  572  that has a area at the top of the substrate. The hole  572  may conform to the dimensions of the conductor hole  550 , or the hole  572  may be smaller in width than the conductor hole  550 . Multiple holes through the substrate  590  and superstrate  570  can substitute for a single hole, so long as all the holes line up and together allow significant sound to pass through. In addition, each of the substrate and superstrate holes must have at least one end at the main conductor hole  550 . 
     In addition, substrate has a first feed hole  580  through which a first conductor or feed probe may pass. First feed hole  580  ends at feedpoint  581  on the underside of the antenna. Feedpoint  581  is centered on diagonal centerline  521 . All holes, whether in the substrate or the superstrate pass in an orthogonal direction in relation to the PCB. A GPS signal carrying conductor attaches by means known in the art to couple the antenna conductor via the feedpoint  581  to filter or amplifier circuitry located on or below the ground plane. 
     In addition, substrate has a second feed hole  585  through which a second conductor or feed probe may pass. Second feed hole  585  ends at feedpoint  586  on the underside of the antenna. Feedpoint  586  is centered on diagonal centerline  522 . All holes, whether in the substrate or the superstrate pass in an orthogonal direction in relation to the PCB. A GPS signal carrying conductor attaches by means known in the art to couple the second antenna conductor via the feedpoint  586  to filter or amplifier circuitry located on or below the ground plane. 
     FIG. 6 a  is a perspective view of an alternate embodiment of the invention which includes a stub antenna  601 , case  600 , PCB  603  and GPS antenna  605 . A case hole  606  is disposed above the GPS antenna hole  607 . Below the GPS antenna hole  607  is a speaker  609 . Stub antenna  601  is situated below the PCB  603 . The stub antenna  601  is the cellular transmit and receive antenna. 
     FIG. 6 b  is a perspective view of an alternate embodiment of the invention which includes a stub antenna  601 , case  600 , PCB  603  and GPS antenna  605 . A case hole  606  is disposed above the GPS antenna hole  607 . Below the GPS antenna hole  607  is a speaker  609 . Stub antenna  601  is situated below the PCB  603 . The stub antenna  601  is the cellular transmit and receive antenna. 
     Operation of the mobile according to the embodiment of the invention is accomplished in one of two modes. For ordinary voice functions of receiving or replaying voice through a speaker, the mobile is operated with the hole of the patch antenna close to the ear of a user. The use of an accessory such as a bud speaker on an extended wire is also an option, wherein the phone may operate in any orientation. Operation of the mobile for purposes of receiving a GPS signal involves holding the mobile in a horizontal, front-up position. In this position, a user may manipulate a keyboard on a mobile phone or any other input device necessary to control the GPS receiver by handling the grasping end of the mobile phone. 
     Although the invention has been described in the context of particular embodiments, it will be realized that a number of modifications to these teachings may occur to one skilled in the art. For example, all manner of fixed, extendable, patch or microstrip antennas could be used for the transmit and receive antenna. Similarly, many elliptically polarized antennas may be substituted for the rectangularly shaped antenna. Thus, while the invention has been particularly shown and described with respect to specific embodiments thereof, it will be understood by those skilled in the art that changes in form and configuration may be made therein without departing from the scope and spirit of the invention.

Technology Classification (CPC): 7