Patent Publication Number: US-7224316-B2

Title: Retractable stubby antenna

Description:
BACKGROUND OF THE INVENTION 
     The invention relates in general to antennas and more specifically to a retractable stubby antenna. 
     Stubby antennas are often utilized in portable communication devices due to their compact design. Due to their structure, stubby antennas are typically shorter than antennas such as ¼ wave or ½ wave whip antennas. Accordingly, the use of a stubby antenna results in an overall smaller size of the portable communication device. Conventional portable communication devices, however, are limited in that position of the stubby antenna is a compromise between performance and size. Conventional stubby antennas are secured in a fixed position relative to the housing of the portable communication device. For example, stubby antennas utilized in conventional cellular telephones typically are secured to the housing such that at least a portion of the antenna is positioned outside the housing in order to increase antenna performance. Greater antenna performance is typically achieved when the antenna is positioned outside of the housing. Such a configuration, however, increases the size of device and results in a more cumbersome form factor. Although the size and form factor of the device may be improved by implementing the device with an internal stubby antenna, such a design results in a degradation of antenna performance. For many situations, the reduced performance does not significantly affect communication. In fringe areas and other situations where antenna performance is critical, however, the reduced antenna performance may not be adequate for communication. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a retractable stubby antenna device within a housing when the antenna is in a retracted position in accordance with the exemplary embodiments of the invention. 
         FIG. 2  is a block diagram of the retractable stubby antenna device within the housing when the antenna is in an extended position in accordance with the exemplary embodiments of the invention. 
         FIG. 3  is a block diagram of the retractable stubby antenna device within the housing when the antenna is in the retracted position in accordance with exemplary embodiments of the invention where the housing connection interface comprises a plurality of connectors. 
         FIG. 4  is a block diagram of the retractable stubby antenna device within the housing when the antenna is in the extended position in accordance with exemplary embodiments of the invention where the housing connection interface comprises a plurality of connectors. 
         FIG. 5  is a block diagram of the retractable stubby antenna device within the housing when the antenna is in the retracted position in accordance with exemplary embodiments of the invention where the antenna connection interface comprises a plurality of connectors. 
         FIG. 6  is a block diagram of the retractable stubby antenna device within the housing when the antenna is in the extended position in accordance with exemplary embodiments of the invention where the antenna connection interface comprises a plurality of connectors. 
         FIG. 7  is a block diagram of the retractable stubby antenna device within the housing when the antenna is in the retracted position in accordance with exemplary embodiments of the invention where the antenna connection interface comprises a single continuous connector. 
         FIG. 8  is a block diagram of the retractable stubby antenna device within the housing when the antenna is in the extended position in accordance with exemplary embodiments of the invention where the antenna connection interface comprises a single continuous connector. 
         FIG. 9  is an illustration of a perspective view of a flex circuit conductor where the antenna connection interface includes a single base connector. 
         FIG. 10  is an illustration of a perspective view of a flex circuit conductor where the antenna connection interface includes a top connector and a single base connector. 
         FIG. 11  is an illustration of a perspective view of the flex circuit conductor where the antenna connection interface includes a single continuous connector. 
         FIG. 12  is an illustration of a perspective view of the flex circuit conductor where the antenna connection interface includes a single continuous connector connected to the helical radiating element at the top of the antenna. 
         FIG. 13  is an illustration of a perspective view of the antenna in accordance with a first exemplary embodiment including a flex circuit and a core with a slot. 
         FIG. 14  is an illustration of a top view of the antenna in accordance with the first exemplary embodiment. 
         FIG. 15  is an illustration of a perspective view of the core in accordance with the first exemplary embodiment. 
         FIG. 16  is an illustration of a top view of the flex circuit before application to the core in accordance with the first exemplary embodiment. 
         FIG. 17  is an illustration of an exploded view of an antenna in accordance with a second exemplary embodiment where the core includes a conductive tube. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In accordance with exemplary embodiments of the invention, a retractable stubby antenna is movable relative to a housing along a longitudinal axis. In a retracted position, at least a portion of the retractable stubby antenna is positioned within the housing. In an extended position, at least a portion of the retractable stubby antenna is positioned outside of the housing such that a greater portion of the antenna is positioned outside the housing in the extended positioned than in the retracted position. A radiating helical element is connected to device circuitry through a connection interface including an antenna connection interface and a housing connection interface. As explained below with reference to the exemplary embodiments, the connection interface may have any of several configurations and provides the electrical connection at least when the antenna is in the retracted position and when the antenna is in the extended position. 
       FIG. 1  and  FIG. 2  are block diagrams of side views of a retractable stubby antenna  102  within a housing  118  in accordance with the exemplary embodiments of the invention. The blocks in  FIG. 1  and  FIG. 2  generally represent exemplary relative configurations of the retractable stubby antenna (“antenna”)  104  in a retracted position and extended position, respectively, and do not necessarily represent relative sizes or positions of the components illustrated. In the exemplary embodiments, the antenna  104  is implemented as part of a mobile communication device such as, for example, a cellular telephone or wireless PDA. The housing  118  in the exemplary embodiment, is the housing of the portable communication device. The retractable stubby antenna  104  is movable along a longitudinal axis  106  relative to the mobile communication device housing  118  and can be retracted or extended relative to the housing  118 . 
     A connection interface  116  connects device circuitry  108  to a helical radiating element  114 . In the exemplary embodiments, the connection interface  116  includes an antenna connection interface  102  that engages a housing connection interface  110  to provide an electrical connection  112  between the helical radiating element  114  and the device circuitry  108  at least when the antenna is in a retracted position and when the antenna  104  is in an extended position. As explained below in further detail, the antenna connection interface  102 , as well as the housing connection interface  110 , may include a single connection contact or multiple connection contacts where the single contact may provide an electrical connection between the device circuitry  108  and the helical radiating assembly in more than one antenna position. 
     The helical radiating element  114  may be formed using any of several techniques. An example of a suitable helical radiating element  114  includes a coiled conductor wrapped around a core material such as dielectric material or plastic. In some circumstances, the core material may be omitted. In the first and second exemplary embodiments discussed below with reference to  FIG. 12 ,  FIG. 13 ,  FIG. 14 ,  FIG. 15 ,  FIG. 16  and  FIG. 17 , the helical radiating element  114  includes a flex circuit having a conductor arranged in configuration resulting in an antenna having similar properties to a helix conductor. 
     The retractable stubby antenna  102  remains in the retracted position during situations when antenna performance in not critical and adequate transmission and reception can be achieved with the antenna  104  in the retracted position. The antenna  104  is extended into the extended position when additional performance is required or the user anticipates that additional antenna performance may be required. In the retracted position, at least a portion of the antenna  104  is positioned within the housing  118 . In the extended position, at least a portion of the antenna  104  is positioned outside the housing  118  where a greater portion of the antenna  104  is positioned outside the housing in the extended position than in the retracted position. 
     In the exemplary embodiments, a user extends and retracts the retractable stubby antenna  102  by grasping and moving the antenna relative to the housing  100 . The antenna  102  slideably moves along an attachment mechanism (not shown). The attachment mechanism is any mechanical configuration that allows the antenna to be moved along the longitudinal axis  106  and depends on the particular antenna implementation. An example of a suitable attachment mechanism includes a sleeve surrounding the antenna  102  that relies on friction between the inner part of the sleeve and at least a portion of the antenna  104  to secure the antenna  104  in the extended and retracted positions. Another example includes a shaft that extends through an opening within the interior of the antenna  102  that utilizes friction forces to maintain the antenna in the positions. The attachment mechanism may be part of, or separate from the connection interface  116 . 
     In some circumstances, matching and tuning circuits are used to increase the performance of the antenna  104  in one or more of the antenna positions. Tuning brackets as well and discrete matching components may be used to change characteristics of the device, ground or other factors affecting performance. For example, tuning elements techniques may be used to optimize the antenna  104  in the various positions due to impedance variations resulting from changes in proximity and relative position of other device components or changes in connection interface  116  characteristics. 
       FIG. 3  and  FIG. 4  are block diagrams of side views of the retractable stubby antenna  104  in accordance with exemplary embodiments of the invention where the antenna connection interface  102  includes a single contact and the housing connection interface  110  includes a plurality of contacts  302 - 304 . In  FIG. 3 , the antenna  104  is in the retracted position and in  FIG. 4 , the antenna  104  is in the extended position. A lower housing contact  302  engages the single contact  102  when the antenna  104  is in the retracted position to form the electrical connection  112  between the helical radiating element  114  and the device circuitry  108 . An upper housing contact  304  engages the single contact  102  when the antenna  104  is in the extended position to form the electrical connection  112  between the helical radiating element  114  and the device circuitry  108 . Accordingly, in the exemplary embodiments discussed with reference to  FIG. 3  and  FIG. 4 , the lower housing contact  302  is positioned within the housing  118  further from the top of the antenna  104  than the upper housing connection  304 . Additional contacts may be included between the upper housing contact  304  and the lower housing contact  302  in some circumstances to provide the electrical connection  112  in antenna positions other than the fully retracted position and fully extended position. 
       FIG. 5  and  FIG. 6  are block diagrams of side views of the retractable stubby antenna  104  in accordance with exemplary embodiments of the invention where the antenna connection interface  102  includes a plurality of contacts  502 - 504  and the housing interface  110  includes a single contact. In  FIG. 5 , the antenna  104  is in the retracted position and in  FIG. 6 , the antenna  104  is in the extended position. A top antenna contact  502  engages the single contact  110  when the antenna  104  is in the retracted position to form the electrical connection  112  between the helical radiating element  114  and the device circuitry  108 . A base antenna contact  504  engages the single contact  110  when the antenna  104  is in the extended position to form the electrical connection  112  between the helical radiating element  114  and the device circuitry  108 . Additional contacts may be included between the top antenna contact  502  and the base antenna contact  504  in some circumstances to provide the electrical connection  112  in antenna positions other than the fully retracted position and fully extended position. 
       FIG. 7  and  FIG. 8  are block diagrams of side views of the retractable stubby antenna  104  in accordance with exemplary embodiments of the invention where the connection interface  102  is a single continuous contact and the housing connection interface  110  includes a single contact. In  FIG. 7 , the antenna  104  is in the retracted position and in  FIG. 8 , the antenna  104  is in the extended position. The continuous contact continuously provides the electrical connection  112  between the helical radiating element  114  and the device circuitry as the antenna is moved along the longitudinal axis  106  of the antenna  104  relative to the housing  118 . Any of several configurations may be used to form a connection interface  116  that allows the electrical connection to be maintained as the antenna  104  is extended and retracted. In a first exemplary embodiment discussed with reference to  FIG. 11 ,  FIG. 12 ,  FIG. 13 ,  FIG. 14 ,  FIG. 15  and  FIG. 16 , a section of flex circuit conductor is positioned within a slot of a core and is contacted by a spring connector of the housing connection interface  110 . In a second embodiment discussed with reference to  FIG. 17 , a ball contact of the housing connection interface  110  slideably contacts the inside of a conductive tube positioned within the center of the core. 
     Other configurations of the antenna connection interface  104  may be used in some circumstances. Combinations and modifications of the configurations discussed above may result in other useful antennas  104 . For example, connection interface  116  may include an antenna connection interface  102  having a single connector that engages a continuous single connector of the housing connector interface  110  to provide a continuous electrical connection  112  while the antenna  104  is moved between the fully retracted and fully extended positions. 
       FIG. 9 ,  FIG. 10 ,  FIG. 11  and  FIG. 12  are illustrations of perspective views of flex circuit conductors  900 ,  1000 ,  1100 ,  1200 , of retractable stubby antennas  104  formed with flex circuits applied to a core. The flex circuit portion  900  includes a conductor arranged in a pattern such that the helical radiating element  114  is formed when the flex circuit is applied to a core. In the interest of clarity, the core is not shown in  FIG. 9 ,  FIG. 10 ,  FIG. 11  and  FIG. 12 . The structure formed by the flex circuit has antenna properties similar to a stubby antenna having a helix coil although the helical radiating elements  114  formed by the flex circuit conductors can also be characterized as a meander line radiating element in some situations. The stubby antennas  104  formed by the flex circuit conductors  900 ,  1000 ,  1100 ,  1200  may include other mechanisms, connectors, and insulators not shown in the figures. For example, a casing, covering, or other protective coating may be applied over the helical radiating element  114  in some circumstances to improve durability and aesthetics. 
       FIG. 9  is an illustration of a perspective view of the flex circuit conductor  900  where the antenna connection interface  102  includes a single base connector. The antenna  104  formed with the flex circuit conductor may be used in implementation shown in  FIG. 3  and  FIG. 4  as well as in an implementation where the housing interface  110  includes a single continuous connector extending though the center of the antenna  104 . 
       FIG. 10  is an illustration of a perspective view of a flex circuit conductor  1000  where the antenna  104  where the antenna interface conductor  102  includes a top connector  304  and a base connector  302 . The antenna  104  formed with the flex circuit conductor may be used in implementation shown in  FIG. 3  and  FIG. 4  as well as in the implementation shown in  FIG. 5  and  FIG. 6 . For example, where only the top connector  304  or only the base connector  302  is used, a housing connection interface  110  may include a two or more connectors to connect to the single contact in the antenna positions. Where both the top connector  304  and the base connector  302  are used during operation, the housing interface connector  110  may include only a single connector. 
       FIG. 11  is an illustration of a perspective view of a flex circuit conductor  1100  where the antenna connection interface  102  includes a single continuous connector. The antenna  104  formed with the flex circuit conductor may be used in implementation shown in  FIG. 7  and  FIG. 8  to provide a continuous electrical connection  112  as the antenna  104  is moved relative to the housing  118 . 
       FIG. 12  is an illustration of a perspective view of the flex circuit conductor  1200  in accordance with the first exemplary embodiment where the antenna connection interface  102  includes a single continuous connector connected at a top of the antenna  104 . The antenna  104  formed with the flex circuit conductor may be used in implementation shown in  FIG. 7  and  FIG. 8  to provide a continuous electrical connection  112  as the antenna  104  is moved relative to the housing  118 . 
       FIG. 13  is an illustration of a perspective view and  FIG. 14  is an illustration of a top view of the exemplary antenna  104  where a flex circuit conductor  1200  of a flex circuit  1302  is applied to a core  1304  to form a helical radiating element  114  in accordance with a first exemplary embodiment. The continuous contact of the antenna connection interface  102  is positioned within a slot  1306  of the core  1304 . In the first exemplary embodiment, the housing connection interface  110  includes a spring contact  1402  that is positioned within the slot  1306  and adjacent to the antenna connection interface  102 . Tension forces, therefore, push the spring contact against the antenna connection interface to maintain the electrical connection  112 . Therefore, in the first exemplary embodiment, the section of conductor on the inside of the slot  1306  is a continuous contact that forms the antenna connection interface  102  and the spring contact  1402  forms the housing connection interface  110 . 
       FIG. 15  is an illustration of a core  1304  having a slot  1306  in accordance with the first exemplary embodiment of the invention. Although other materials may be used, the core  1304  is formed from plastic in the first and second exemplary embodiments. The core  1304  has tapered structure with a substantially flat and parallel top  1502  and bottom  1504  forming a conical configuration. An inside edge  1506  of the slot  1306  is provides a surface for applying the section of conductor of the flex circuit that forms the antenna connection interface  102 . 
       FIG. 16  is an illustration of a top view a flex circuit  1302  including the flex circuit conductor  1200  arranged in a pattern that forms a helical conductor when applied to the core  1304 . The shape and size of the flex circuit  1302  allow the flex circuit to be wrapped around conical core  1304  such that the flex circuit conductor forms the helical radiation element  114 . The flex circuit is folded along fold lines  1602  such that the section of conductor is positioned along the inside edge  1506  of the slot  1306 . 
       FIG. 17  is an illustration of an exploded view of the antenna in accordance with the second exemplary embodiment of the invention where the single continuous connector of the antenna connection interface  102  is a conductive tube  1702  within the center of a core  1704 . The conductive tube  1702  fits into circular channel  1706  within the core  1704 . A screw  1708  threaded into the conductive tube  1702  secures the conductive tube  1702  to the core  1704  and provides an electrical connection between the flex circuit conductor  1710  of the flex circuit  1712  and the conductive tube  1702 . A ball contact  1714  of the housing connection interface  110  snugly moves within the conductive tube  1702  as the antenna  104  is moved along the longitudinal axis  106  relative to the housing  118 . Positioning bumps  1716  within the conductive tube  1702  provide a mechanism for holding the antenna  104  in the retracted position and the extended position. 
     Therefore, the exemplary retractable stubby antennas  104  include connection interfaces  116  that provide an electrical connection between the helical radiating element  114  and circuitry  108  within the portable communication device at least when the antenna  104  is in the retracted position and the extended position. In some embodiments, the electrical connection  112  is continuous as the antenna  104  is moved relative to the housing  118 . The antenna  104  is placed in the retracted position to minimize size of the portable device but can be extended to improve antenna performance. 
     Clearly, other embodiments and modifications of this invention will occur readily to those of ordinary skill in the art in view of these teachings. The above description is illustrative and not restrictive. This invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.