Patent Publication Number: US-6703978-B2

Title: Dual telescopic whip antenna

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention generally relates to wireless communications antennas and, more particularly, to a dual telescopic whip antenna that is especially useful with small portable wireless communication devices. 
     2. Description of the Related Art 
     The size of portable wireless communications devices, such as telephones, continues to shrink, even as more functionality is added. As a result, the designers must increase the performance of components or device subsystems while reducing their size, or placing these components in less desirable locations. One such critical component is the wireless communications antenna. This antenna may be connected to a telephone transceiver, for example, or a global positioning system (GPS) receiver. 
     One antenna design is the patch antenna, which can be incorporated into a wireless device circuit board or the device chassis. However, the close proximity of the chassis to the user can limit the performance of such an antenna. Typically, better communication results are achieved using a whip antenna. Using a wireless telephone as an example, it is typical to use a combination of a helical and a whip antenna. In the standby mode with the whip antenna withdrawn, the wireless device uses the stubby, lower gain helical coil to maintain control channel communications. When a traffic channel is initiated (the phone rings), the user has the option of extending the higher gain whip antenna. Some devices combine the helical and whip antennas. Other devices disconnect the helical antenna when the whip antenna is extended. 
     The whip antenna has a physical length, when extended, related to the antenna operating frequency. When withdrawn, the whip antenna must fit within the constraints of the wireless device chassis. Therefore, as the wireless device chassis decreases in size, the extended length of conventional whip antennas has necessarily decreased. A shorter whip antenna can be made to operate at the same frequency as longer whip antennas by using higher dielectric constant materials in the antenna fabrication. However, the use of higher dielectric constants makes for a lower gain antenna, and a poorer performing wireless device. 
     One popular solution to the above-mentioned length problem has been to fabricate the whip antenna as a wire with a telescoping tube section. When the antenna is withdrawn, the wire section is withdrawn into the tube, with the tube being withdrawn into the chassis. When extended, the combination of the wire and tube section define the antenna length. 
     As mentioned above, one advantage of the whip antenna is a reduced proximity to the human user, who blocks the signal path around the antenna. Whip antenna performance can be further enhanced by further reducing the proximity of the antenna to the user. Safety is another reason for reducing proximity, as there is concern that the proximity of the human head to wireless transmissions may be a health hazard. For these reasons it is desirable to angle the whip antenna from the device chassis when extended, away from the user. When withdrawn, such an angled antenna would necessarily reside in a channel formed through the center of the device chassis (where the electronic components reside), unless the withdrawn antenna can be bent. However, the relatively rigid telescoping tube is not completely flexible. Further, a truly flexible telescoping tube would be easily damaged when the phone is accidentally dropped. 
     It would be advantageous if a high performance whip antenna could be withdrawn into a compact length using more than one telescoping section. 
     It would be advantageous if a telescoping whip antenna could be angled away from the device chassis when extended. 
     SUMMARY OF THE INVENTION 
     The present invention describes a dual telescope whip antenna. Since two telescoping tubes are used, having approximately half the length of a conventional single tube design, the antenna can be extended at an angle with respect to its withdrawn (contracted) position. That is, the shorter tubes can be inserted into the chassis collection channel at an angle. The antenna has a physical length that is not limited to the chassis collection channel length, or the angle between the antenna withdrawn and extended orientations. 
     Accordingly, a dual telescopic whip antenna is provided. The antenna comprises a radiator including a conductive wire, and a first telescoping tube section having a first end to accept the wire and an antenna port at a second end. The radiator also includes a second telescoping tube section having a first end to accept the other end of the wire. The radiator has an extended position length that is approximately equal to the sum of the wire length, the first tube length, and the second tube length. The radiator has a contracted position with the wire length substantially withdrawn in the first and second tubes. 
     In some aspects the antenna further comprises a chassis with a stopper channel assembly to accept the first and second tubes in the radiator contracted position and to limit the extension of the first tube from the chassis in the radiator extended position. The stopper channel assembly also includes a transmission line terminal that is connected to the antenna port in the radiator extended position. 
     Additional details of the above-described antenna, a wireless communications device dual telescopic antenna system, and a dual telescopic antenna method are described below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 2 is a schematic block diagram of the present invention wireless communications device dual telescopic antenna system. 
     FIG. 1 is a partial cross-sectional view of the present invention dual telescope whip antenna of FIG.  2 . 
     FIG. 3 is a partial cross-section view of the dual telescope whip antenna in the contracted, or withdrawn position. 
     FIG. 4 is a partial cross-sectional view featuring the chassis stopper channel. 
     FIG. 5 is a partial cross-sectional view of the present invention radiator withdrawn in a chassis collection channel. 
     FIG. 6 is a flowchart illustrating the present invention dual telescopic whip antenna method. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2 is a schematic block diagram of the present invention wireless communications device dual telescopic antenna system. The system  100  comprises a wireless communications transceiver  102  having a communications port. A transmission line  104  has a first end  106  connected to the transceiver communications port and a second end  108 . The transmission line second end  108  is connected to a dual telescope whip antenna  200 . The antenna  200  can be tuned to operate at frequencies such as 824 to 894 megahertz (MHz), or 1850 to 1990 MHz to support wireless telephone communications. The antenna  200  can also be tuned to operate between 1565 and 1585 MHz to support the reception of GPS satellite signals. 
     FIG. 1 is a partial cross-sectional view of the present invention dual telescope whip antenna of FIG.  2 . The dual telescopic whip antenna has a radiator  202  that includes a conductive wire  204  having a length  206 , a proximal end  208 , and a distal end  210 . A first telescoping tube section  212  has a length  214 , an orifice at a first end  216  to accept the wire proximal end  208 , and an antenna port at a second end  218 . The antenna port can be any convention means known in the art of connecting to an antenna. For example, the antenna port can be formed as a conductive plug that becomes a pressure-fit connection in a stopper channel assembly. A second telescoping tube section  220  has a length  222  and an orifice at a first end  224  to accept the wire distal end. The second tube  220  has a second end  226 . The radiator is shown in the extended position with a length  228  that is approximately equal to the sum of the wire length  206 , the first tube length  214 , and the second tube length  222 . In some aspects, the wire  204  is a nickel titanium material, and the first and second tubes  212 / 220  are a stainless steel material. 
     FIG. 3 is a partial cross-section view of the dual telescope whip antenna in the contracted, or withdrawn position. The radiator  202  has a contracted position with the wire length  206  substantially withdrawn in the first and second tubes  212 / 220 . 
     FIG. 4 is a partial cross-sectional view featuring the chassis stopper channel. In some aspects of the system, the first and second tubes  212 / 220  have a first diameter  400 . However, the tube diameters need not necessarily be identical. The first tube second end  218  is shown formed as a butt having a second diameter  404  greater than the first diameter (the diameter of the first tube  212 ). A chassis  406  is shown with a stopper channel assembly  408  with a stopper channel having a third diameter  410  less than the second diameter  404 . More specifically, the stopper channel assembly is shown formed with a threaded section mating to a nut  412 . The nut  412  can be connected with a spring clip to the transmission line second end (see FIG.  2 ), not shown, and acts as the transmission line terminal. Alternately, the stopper channel assembly can be formed as a conductive snap that is pressure fit inside the chassis  406  against a transmission line terminal. There are many other conventional means of securing a stopper channel assembly  408  to a chassis  406  that are not described, but which would be suitable for use with the present invention. 
     There are many conventional antenna/transmission line interfaces that would be practical for use with the present invention system. The transmission line connected to the nut  412  can be a coax cable, microstrip, stripline, or any conventional transmission line. The ground polarity of the transmission line is typically connected to a circuit board or chassis section ground (not shown) that acts as a counterpoise to the radiator. 
     The first tube antenna port at the second end  218  is connected to the transmission line, through the nut  412 , in the radiator extended position. The stopper channel assembly  408  accepts the first and second tubes  212 / 220  in the radiator contracted position. The stopper channel  408  assembly, as shown, limits the extension of the first tube  212  from the chassis  406  in the radiator extended position. 
     FIG. 5 is a partial cross-sectional view of the present invention radiator withdrawn in a chassis collection channel. The chassis  406  includes a collection channel  500  intersecting the stopper channel to accept the first and second tubes in the contracted position. Reference designator  502  represents the orientation of the collection channel and reference designator  504  represents the orientation of the stopper channel. The angle formed at the intersection (θ)  506  can be greater than zero degrees because of the greater flexibility of the dual telescope sections  212  and  220 . Depending on factors such as the diameter of the stopper channel, the diameter of the stopper channel, the outside diameters of the telescope tubes, and the flexibility of the tubes, the angle  506  can be greater than 1 degree. In some aspects, the angle  506  can be greater than 5 degrees. 
     As seen in FIG. 4, a protective cap  420  has a first end  422  attached to a second end  226  of the second tube  220 . The cap  420  includes a second end with a stop  424  having a fourth diameter  426  greater than the second diameter  410 . The interface between the stopper channel  408  and the stop  424  can limit the insertion of the second  220  tube into the chassis  406  when the radiator is in the contracted position. 
     Returning to FIG. 1, the wire distal end  210  is formed in a butt  240  having a fifth diameter  242  and the wire proximal end  208  is formed in a butt  244  having a sixth diameter  246 . Note, the fifth diameter  242  may equal the sixth diameter  246  in some aspects. The first tube first end  216  orifice has a diameter  248  less than the sixth diameter  246  to limit the extension of the wire  204  in the radiator extended position. Likewise, the second tube first end  224  orifice has a diameter  250  less than the fifth diameter  242  to limit the extension of the wire  204  in the radiator extended position. 
     The first tube second end  218  has an interior channel diameter less than the sixth diameter  246  to limit the withdrawal of the wire  204  into the first tube  212 , when the radiator is in the contracted position. In the extreme case as shown, the first tube second end is completely sealed. Likewise, the second tube second end  226  has an interior channel diameter  254  less than the fifth diameter  242  to limit the withdrawal of the wire  204  into the second tube  220  when the radiator is in the contracted position. In some aspects, the second end  226  is sealed, or partially sealed by the cap (see FIG.  4 ). 
     Returning to FIG. 4, in some aspects of the system the stopper channel includes a helical antenna  450  connected to the transmission line terminal (nut)  412  when the radiator is in the contracted position. The helical antenna  450  is shown as a coil in cross-section. In some aspects of the system (not shown), the helical antenna  450  is disconnected when the dual telescopic whip antenna is extended. 
     FIG. 6 is a flowchart illustrating the present invention dual telescopic whip antenna method. Although this method is depicted as a sequence of numbered steps for clarity, no order should be inferred from the numbering unless explicitly stated. It should be understood that some of these steps may be skipped, performed in parallel, or performed without the requirement of maintaining a strict order of sequence. The methods start at Step  600 . Step  602  forms a conductive wire having a length. Step  604  forms a first telescoping tube having a length, an orifice at a first end to accept the wire, and an antenna port at a second end. Step  606  forms a second telescoping tube having a length and an orifice at a first end to accept the wire. Step  608  extends the wire from the first and second tubes to form an extended radiator having a length that is approximately equal to the sum of the wire length, the first tube length, and the second tube length. Step  610  electro-magnetically communicates at an operating frequency such as 824 to 894 megahertz (MHz), 1565 to 1585 MHz, or 1850 to 1990 MHz. Step  612  withdraws the wire length substantially inside the first and second tubes to form a contracted radiator. 
     In some aspects Step  607   a  forms a chassis stopper channel having a diameter. Then, withdrawing the wire length in Step  612  includes accepting the first and second tubes through the stopper channel. Extending the wire in Step  608  includes using the stopper channel to limit the extension of the first tube from the chassis. 
     In other aspects of the method Step  607   b  forms a collection channel intersecting the stopper channel to accept the first and second tubes when the radiator is contracted. Typically, the chassis channel intersects the stopper channel at an angle of greater than 1 degree. In some aspects the chassis channel intersects the stopper channel at an angle of greater than 5 degrees. 
     In some aspects Step  607   c  forms a protective cap having a first end attached to the second tube. Then, withdrawing the wire length in Step  612  includes using the cap to limit the insertion of the second tube into the chassis when the radiator is contracted. 
     In other aspects, forming a conductive wire in Step  602  includes forming a butt on each wire end. Then, extending the wire in Step  608  includes using the first tube first end orifice and the second tube first end orifice to limit the extension of the wire butt ends from the first and second tubes when the radiator is extended. 
     In some aspects forming a first tube in Step  604  includes forming a first tube with a second end having a diameter. Forming a second tube in Step  606  includes forming a second tube with a second end having a diameter. Then, withdrawing the wire length in Step  612  includes using the first and second tube second end diameters to limit the insertion of the wire butt ends into the first and second tubes when the radiator is contracted. 
     A dual telescopic antenna system and method have been presented. Specific examples of an antenna system have been given in the context of a wireless telephone device, but the invention is not necessarily so limited. Further, although only two telescoping sections have been specifically described, the present invention concept is applicable to multiple telescopic sections. Other variations and embodiments of the invention will occur to those skilled in the art.