Abstract:
The present invention relates to problems with how to achieve a reliable and efficient connection between circuitry in a radio communication device and an extendable and retractable antenna device, which is operable in both extended and retracted position as well as during extension and retraction. This problem is solved by providing an antenna device with radiating means, movable between an extended and a retracted position. The antenna device having a feeding arrangement comprising at least a first connection member ( 306, 307, 308; 801, 802, 803 ) electrically coupled to and movable with the radiating means. The feeding arrangement further comprises at least a second connection member ( 309, 310; 903, 904, 905, 906, 907; 1003, 1004, 1005 ) arranged for being electrically coupled to the first circuitry and fixedly mounted on a support unit. Moreover, the first connection member being electrically coupled to the second connection member in all positions between and including the extended and retracted positions.

Description:
TECHNICAL FIELD OF INVENTION 
     The present invention relates in general to an antenna device, for receiving and transmitting RF signals with .a sliding connector means, and more specifically to an antenna device for receiving and transmitting RF signals, which is electrically coupled to radio circuitry through a sliding connector during its extension and retraction. 
     DESCRIPTION OF RELATED ART 
     Some of the driving forces of the mobile communication industry today are availability and size. A user of a hand-held mobile communication device requires to be reached wherever his location may be. This puts requirements on the operator to have good coverage of their mobile network, but for large unpopulated or scarcely populated areas, this is not possible with any reasonable economy. One solution for a user who frequently travels to unpopulated locations is to instead use a satellite communication telephone. 
     Such a user will still have requirements on the size of his satellite communication device, as he undoubtedly will compare his ordinary cellular communication device with his satellite communication device. Since the distance to orbiting or stationary satellites is so great, satellite antennas need to be able to handle very weak signals. The antennas used will thus generally be larger and require less obstacles compared to antennas for cellular communication devices, and will consequently take a considerable amount of the space of a satellite communication device. The need for reducing the size of the antennas for satellite communication devices is thus large and anyone being able to reduce the size for such an antenna will have a considerable competitive advantage. 
     The somewhat larger antenna unit in a satellite communication device has posed some problems. In one set of prior art antennas the antenna unit can be rotated around an axis so as to fold the antenna unit along one side of the satellite communication device when not in talk position. Thereby, the space taken by the terminal device is considerably less when in a standby mode. One problem, which occurs with this solution, is that the antenna is badly suited to receive paging signals from the satellite in the standby mode. This can be remedied by introducing an extra paging antenna on the top of the satellite communication device specifically designed for receiving signaling in the standby mode. This, however generates a new problem namely with how to switch between the different antennas in dependence of the operating mode. 
     Another solution requires the satellite device to have a specific position during standby, such as upside down. The U.S. patent application Ser. No. 5,628,057 discloses a satellite communication device with an antenna unit connected thereto at a pivot point. 
     SUMMARY OF INVENTION 
     The object of the present invention is thus to achieve a reliable and efficient connection between circuitry in a radio communication device and an extendable and retractable antenna device, which is operable in both extended and retracted position. 
     Another object of the present invention is to achieve a reliable and efficient connection between circuitry in a radio communication device and an extendable and retractable antenna device, which is operable during extension and retraction. 
     The problems described above, how to achieve a reliable and efficient connection between circuitry in a radio communication device and an extendable and retractable antenna device, which is operable in both extended and retracted position as well as during extension and retraction, is solved by providing an antenna device with radiating means, movable between a extended and a retracted position. Said antenna device having a feeding arrangement comprising at least a first connection member electrically coupled to and movable with said radiating means. Said feeding arrangement further comprises at least a second connection member arranged for being electrically coupled to said first circuitry and fixedly mounted on a support unit. Moreover, said first connection member being electrically coupled to said second connection member in all positions between and including said extended and retracted positions. 
     In more detail the objects of the present invention are obtained, according to a first embodiment, by providing an antenna device according to the above, wherein said first connection member comprises a multitude of resilient conductive members. Said second connection member comprising a multitude of elongated conductive strips arranged on one side of a dielectric medium and with a ground plane arranged on an opposite side of said dielectric medium. Each resilient conductive member of said multitude of conductive members being arranged to exert a force against a corresponding elongated conductive strip so as to enable electrical coupling between said conductive member and said conductive strip. Each resilient conductive member being arranged to slide along said elongated conductive strip when said radiating means moves between said first and second positions. 
     According to another embodiment, the objects of the present invention are obtained by providing an antenna device according to the above, wherein said antenna device further comprises a switch. Said switch being arranged for disconnecting said second connection member and connecting said first circuitry to said radiating means when said radiating means is in said second position. 
     According to another embodiment, the objects of the present invention are obtained by providing an antenna device according to the above, wherein at least one of said elongated conductive strips having irregular shaped edges. Said irregular shaped edges being adjusted so that the elongated conductive strip having an input impedance, seen from a first point where the resilient conductive member connects to the elongated conductive strip when said radiating element is in extended position, and towards said open end which is very large compared to the input impedance seen from said first points and towards the radiating means. These irregular shaped edges can for instance be obtained by protrusions and/or recesses. 
     An advantage with the present invention is that a reliable connection between the circuitry in a radio communication device and an extendable radiating means is obtained in extended and retracted position as well as during extension and retraction. 
     Another advantage with the present invention is that the shortest possible electrical transmission distance is kept between the radiating element and the radio circuitry in both extended and retracted position. 
     An advantage, according to one embodiment of the invention, is that several independent, electrically separate connections between circuitry in a radio communication device and an extendable radiating means can be obtained easily and reliably. 
     An advantage, according to one embodiment of the invention, is that power and control signals can easily and reliably be fed to circuitry located on the radiating means. 
     An advantage, according to one embodiment of the invention, is that transmitted and received signals can be conducted on separate lines between the radiating means and the circuitry in the radio communication device. 
     An advantage, according to one embodiment of the invention, is that signals to different radiating elements, arranged for receiving and transmitting RF signals in different systems can be conducted on separate lines between the radiating means and the circuitry in the radio communication device. 
     Another advantage, according to one embodiment of the invention, is that said elongated conductive strip may have irregular shaped edges, such as protrusions or recesses, so that the elongated strip is to be regarded as an open circuit when said radiating means is in its extended position. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention and wherein 
     FIG. 1 shows an prior art antenna arrangement for a satellite communication terminal having a rotatable main antenna and an auxiliary antenna, 
     FIG. 2 shows an axially extendable antenna means connected with coaxial cables to the circuitry of a radio communication device, 
     FIG. 3 shows a perspective view of an antenna device and radio communication device according to a first embodiment of the invention, 
     FIG. 4 shows a detailed view of the connector member according to the first embodiment of the invention, 
     FIGS. 5 a ,  5   b  and  5   c  schematically shows different electrical configurations according to a preferred embodiment of the invention, 
     FIG. 6 shows a schematic signal strength diagram during the extension of the inventive antenna means according to one embodiment of the invention, 
     FIG. 7 schematically shows the inventive antenna device according to a third embodiment of the invention, 
     FIGS. 8 a ,  8   b  and  8   c  shows a detailed view of a connector member according to a fourth embodiment of the invention, 
     FIGS. 9 a  and  9   b  shows different views of a connector member according to a fifth embodiment of the invention, 
     FIGS. 10 a  and  10   b  shows different views of a connector member according to a sixth embodiment of the invention, 
     FIG. 11 shows a view of a connector member according to a seventh embodiment of the invention, 
     FIG. 12 schematically shows an exploded view according to a preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows a radio communication device with a prior art antenna  101  for satellite communication. The antenna  101  is mounted on the backside of the radio communication device at a pivot point and can thus be rotated to an active position, pointing essentially upwards, or to an inactive position, pointing essentially downwards. A patch antenna  102  is mounted on top of the radio communication device for receiving paging signals when the primary antenna  101  is in an inactive position. 
     The patch antenna  102  can be avoided if the radio communication device is positioned up side-down. The primary antenna  101  would then be pointing essentially upwards, towards the communication satellite, and would be able to receive paging signals. 
     If an extra antenna unit or awkward positioning requirements is to be avoided an extendable antenna unit may be used instead. With an extendable and retractable antenna unit, the same antenna unit may be used for paging signals as well as for use in talk position. 
     FIG. 2 shows a radio communication device  201  with extendable radiating means  202 . The radiating means is connected to circuitry  203  mounted on a printed circuit board PCB  204  in the radio communication device  201 . The connection is achieved with a first coaxial cable  205  and a second coaxial cable  206 . 
     During manufacturing, the use of coaxial cables would introduce some problems. It is difficult to mount the cable connection to the connections in the circuitry and the radiating means in an efficient manner. If several different connections between the radiating means  202  and the circuitry  203  is needed each new coaxial cable increase the difficulties in the manufacturing process. Therefore is the use of coaxial cable connections a feasible but a cumbersome and expensive solution. The connections and the cable will also introduce unnecessary losses in the transmission of signals between the circuitry  203  and the radiating means  202 . This has its greatest disadvantage when the radiating element is in its extended position and the geometric distance between the circuitry and the radiating element is relatively short but the distance using coaxial cables is still relatively long. 
     FIG. 3 shows a radio communication device  301  with a radiating means  302  and circuitry  303  mounted on a PCB  304 . Feeding arrangement  305  being arranged for feeding signals from the circuitry  303  to the radiating means  302 . Said feeding arrangement  305  comprises first, second and third connection members denoted  306 ,  307  and  308  respectively, and fourth, fifth and sixth connection members denoted  309 ,  310  and  311 . 
     The first, second and third connector member are so called pogo pins, telescoping contacts with spring action, mounted on, and movable with the radiating means  302 . The fourth, fifth and sixth connector members are elongated conductive strips mounted on a dielectric medium with conductive backside coupled to ground and fixedly attached to the casing of the radio communication device. The casing thus act as a support member to the elongated conductive strips. The pogo pins  306 ,  307  and  308  are resilient, spring loaded and exert a force on elongated conductive strips  309 ,  310  and  311  so as to enable electrical coupling between the first and fourth, the second and fifth and the third and sixth connector member, respectively. Thus, electrical coupling is achieved between the circuitry  303  and the radiating means  302  when the radiating means is in retracted and extended position as well as in all positions between. For RF signals the transmission characteristics of the transmission line from the circuitry to the radiating element via the connector members will vary during extension and retraction as disclosed in FIG.  6 . 
     In FIG. 6 is the damping of the signal plotted against the distance the antenna is injected into the well of the portable phone for two different frequencies. As can be seen in FIG. 6 one dip occurs for the 90.0 MHz frequency and two dips occur for the 1600 MHz frequency. The dip in transmission efficiency will not have a substantial adverse effect of the performance of the communication since the communication system is designed for allowing short breaks in transmission. Of course, for signals which is not RF signals, such as power and control signals, no such dips in transmission will occur. 
     The radiating means further comprises a first radiating element  312 . The first radiating element consists of a number N, where N being an integer, greater than 1, of conductive, helical strips arranged for receiving and transmitting circular polarized RF signals. It would of course also be possible to use any other radiating means suitable for receiving and transmitting circular polarized RF signals, such as helical conductive wires. The first radiating element  312  is connected, through a phasing network, to the first connector member  306  and further through the fourth connector member  309  to the circuitry  303 . 
     A second radiating element is denoted  313  and is arranged for receiving and transmitting planar polarized RF signals such as is used for earth based radio communication, for instance GSM, DECT, AMPS, DAMPS, PCS etc. The second radiating element is connected to the third connector member  308  and further through the sixth connector member  311  to the circuitry  303 . 
     A protective cap is denoted  314  and is only partly shown for sake of clarity. The cap  314  also comprises guiding protrusions (not shown) which connects with corresponding guiding surfaces positioned on the surrounding walls (not shown). Alternatively, the guiding profiles may be positioned on a support, arranged for supporting the first radiating element  312 . 
     FIG. 4 shows a top view of the radiating means  302  and more clearly discloses a well from which the radiating means  302  is extendable and retractable. Guiding protrusions  402  engage guiding surfaces  403  so that a sliding movement of the radiating means  302  is possible. This makes it possible to extend the radiating means  302  out of the well and retract said means back into the well again. 
     FIG. 12 shows an exploded view of the main components according to one embodiment of the invention. In this embodiment five different connections are used between the radiating means and the circuitry in a radio communication device. A first PCB is denoted  1201  and a second PCB is denoted  1202 . A first radiating element is denoted  1203  and is consisting of a number of helically wounded conductive strips on a thin flexible carrier mounted on a hollow support  1204 . Said first radiating element is arranged for receiving and transmitting circular polarized RF signals mainly for communication with a satellite. Said first radiating element  1203  is coupled to a phasing network and a diplexer (not shown) when necessary. The phasing network being arranged to transform circularly polarized RF signals to and from signals suitable for transmission to circuitry in a radio communication device. The diplexer separates received signals R x  and transmitted signals T x  into two separate signals carried on two separate conductors, alternatively two separate phasing networks can be utilized for the transmission frequency T x  and the receiving frequency R x . The T x  and R x  signals are connected to a first and second connector member  1205  and  1206  respectively, which in turn are coupled to third and fourth connector member  1207  and  1208  respectively. Said third and fourth connector members  1207  and  1208  being further connected to circuitry in a radio communication device. On the connection established over said first and third, and second and fourth connector members is also power and control signals, for instance to a LNA (Low Noise Amplifier), conducted to the phasing network and the diplexer positioned on the first or second PCB  1201 ,  1202 . Alternatively may separate connector members be used for the transfer of power and control signals to the phasing network and diplexer. 
     A second radiating element is denoted  1209  and is a helical conductive coil arranged for receiving and transmitting RF signals in for instance the GSM, DECT or AMPS systems. The second radiating element is positioned inside the support  1204  and is connected to circuitry in a radio communication device through fifth, sixth, seventh and eighth connector members denoted  1210 ,  1211 ,  1212  and  1213  in a similar way as was described for said first radiating element. However, no phasing network or diplexers are generally required. Ninth and tenth connector members denoted  1214  and  1215  are used for carrying signal ground from the circuitry. Said second, fourth, sixth, eight and tenth connector members are mounted on a dielectric medium or carrier  1216  which on the backside has a ground plane  1217 . 
     It would of course also be possible to have separate signal ground strips between every signal carrying strip, or several signal ground strips surrounding on signal strip etc. 
     One advantage with using strips compared to coaxial connections is that loss in connections and transmission is significantly reduced. 
     FIGS. 5 a ,  5   b  and  5   c  shows schematic circuit diagrams of different configurations according to a preferred embodiment of the invention. With  501  is a first connector member denoted and with  502  is a second connector member denoted. With  503  is a radiating means denoted and  504  denote a circuitry in a radio communication device. Even though, for sake of clarity, only one line is drawn in FIG. 5 between the circuitry  504  and the radiating means  503  it is to be understood, as been shown above, that this line may represents two or more elongated conductive strips and connectors constituting a transmission line. Said second connector member  502  has a first end denoted  505  and a second end  506  connected to said circuitry  504 . 
     As disclosed in FIG. 5 a , when the radiating means is in its retracted position the second connector member  502  electrically connects the radiating means  503  to the circuitry  504 . In FIG. 5 b  the radiating means  503  is shown in its extended position connected to the circuitry  504 . The first end  505  is in this position an open end. In FIG. 5 b  the electrical length of the second connector member  502  is selected so that the second connector member  502  has very high impedance at the second end  506  compared to the radiating means  503 , for the selected frequency band, and can therefore be regarded as a open circuit. In FIG. 5 c , the radiating means  503  is disclosed in a position between the extended and the retracted position. The radiating means  503  is still coupled to the circuitry  504  through said first and second connector members. 
     FIG. 7 shows an arrangement where circuitry  701  is connected to second connector member  702  at the first end  703 . When the radiating means  704  is in its retracted position the second connector member  702  is an open stub and may be disconnected with a switch (not shown) or adjusted to high input impedance as described above. 
     FIG. 8 a  shows a side view, FIG. 8 b  shows a front view and, FIG. 8 c  shows a top view of connector members, 801 ,  802  and  803  where flexible, wire members are used. A radiating means is denoted  804 , on and/or in the support is radiating elements mounted (not shown). As the radiating means  804  is extended or retracted, the resilient members  801 ,  802  and  803  will glide on elongated connector members (not shown). As is shown in FIG. 8 a  the resilient connector members  801 ,  802  and  803  is flexible and will exert a force on the elongated connector members so as to enable electrical contact. In FIG. 8 a  one wire member is shown depressed to indicate the flexibility of the wire members. 
     FIG. 9 a  shows a front view of an arrangement with elongated conductive strips disclosed in FIGS. 3 and 12, and FIG. 9 b  shows a view taken at I—I. A dielectric medium or carrier is denoted  901  and a conductive sheet is denoted  902 . The conductive sheet  902  being coupled to ground. First, second, third, fourth and fifth elongated conductive members are mounted on the dielectric carrier  901  and denoted  903 ,  904 ,  905 ,  906  and  907 . 
     FIG. 10 a  shows a front view according to another embodiment of said elongated conductive strips and FIG. 10 b  shows the arrangement of FIG. 10 a  taken at line II—II. A dielectric medium is denoted  1001  and a conductive sheet is denoted  1002 . The conductive sheet  1002  is coupled to ground. First, second and third elongated conductive strips are denoted  1003 ,  1004  and  1005  respectively. The third elongated strip  1005  has protrusions  1006  the adjust the electrical length of the third elongated conductive strip  1005 . 
     FIG. 11 shows the elongated conductive strips according to another embodiment. A first dielectric medium or carrier is denoted  1101 , a second dielectric medium or carrier is denoted  1102  and a ground plane is denoted  1103 . The first and second dielectric carriers are arranged with a small distance so that a recess  1104  is achieved where a first connector member (not shown), electrically connected to radiating means (not shown), may electrically couple to said ground plane  1103 . 
     It is of course also possible to combine different aspects of the different embodiments to achieve a multiple of new slightly different embodiments. These slightly new embodiments are also intended to be included in the conceptual scope of the invention. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.