Abstract:
A moveable antenna system with a position sensor circuit and a circuit which transmits the position sensing data and the radio frequency (RF) on the same wire. The position sensor comprises a sensing pin and a sense track concentric with the coaxial cable for the RF signal. When the antenna is in the preferred position for transmission, the sensing pin is in contact with the sense track, thus closing a switch, allowing the unit to transmit RF signals. Otherwise, the sensing pin is not in contact with the sense track, preventing any transmission of data. The signal that results from the opening and closing of the switch is carried on the same transmission line as the RF signal. This is accomplished by using capacitors to block direct current (DC) from the transmission line and using resistors and shunt capacitors to prevent any leakage of RF signals onto the sensing circuit.

Description:
FIELD OF THE INVENTION 
     The present invention relates, generally, to a moveable antenna for use with a cellular telephone, radio, or other communication device, and more particularly to an antenna employing a hybrid radio frequency (RF) and direct current (DC) circuit for transmitting RF signals to and from its associated communication device. 
     BACKGROUND 
     Portable communication devices, such as cellular telephones, two-way and multi-party radio communication devices, and the like often employ a retractable and sometimes even a removable antenna assembly. To achieve optimum performance, it is advisable to orient the antenna vertically, particularly when receiving radio frequency (RF) transmission which is vertically oriented. However, communication devices (e.g., cellular telephones) having antennas which are not rotatable often suffer impaired transmission performance if the antennas are not oriented vertically during normal use of the cellular phone. 
     Other known cellular telephones employ antennas which are removable. Typically, these phones continue to transmit an RF signal even when the antenna is removed. This can result in unnecessary power depletion and unnecessary wear on the electrical components which make up the transmission circuit. 
     Existing cellular telephones which employ a moveable antenna utilize a dedicated RF circuit for transmitting and receiving RF signals, as well as a dedicated DC circuit for carrying a signal to the telephone host processor which indicates antenna orientation and whether the antenna is connected or removed. The use of such a dedicated RF circuit and a dedicated DC circuit results in increased manufacturing costs and reduces reliability and performance. 
     A positionable antenna assembly for use with portable communication devices is thus needed which overcomes the shortcomings of the prior art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like numerals denote like elements, and: 
     FIG. 1 is a schematic representation of a communication device showing its antenna in the stowed position; 
     FIG. 2 shows the communication device of FIG. 1 with its antenna in a partially extended position; 
     FIG. 3 shows the communication device of FIGS. 1 and 2 with its antenna in the fully extended position. 
     FIG. 4 is a partially exploded view of an antenna connector assembly aligned with a printed wiring board of a mating communication device; 
     FIG. 5 is an alternate view of the assembly of FIG. 4; 
     FIG. 6 is a schematic representation of an antenna connector circuit; 
     FIG. 7 is a schematic representation of a board track circuit; 
     FIGS. 8 through 10 are schematic representations of alternate embodiments of the board track circuit of FIG. 7; 
     FIG. 11 is a schematic block diagram of a hybrid RF and DC circuit for connecting an antenna with a communication device; and 
     FIG. 12 is a detailed electrical schematic diagram of a hybrid RF and DC circuit for use in connecting an antenna to a communication device. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIGS. 1-3, a communication device  102  is equipped with an antenna  108  mounted to communication device  102  via a connector arm  106  and a pivot  104 . Communication device  102  may comprise a cellular telephone, a portable telephone, a wireless device such as a radio communication device, or virtually any other electronic communications device which employs radio frequency (RF) transmission. Communication device  102  includes an RF circuit (discussed below in conjunction with FIGS. 11 and 12) configured to communicate with a remote transceiver. These transceivers are typically located on towers on buildings, mountains, or the like, or on orbiting satellites. In any case, it is often desirable to operate communication device  102  with antenna  108  extended in the vertical position. However, it is often uncomfortable or inconvenient for a user to position communication device  102  such that its antenna is maintained vertically and engage in conversation at the same time. This problem is exacerbated when the user is laying down, driving or otherwise constrained. Consequently, quality of RF reception is compromised. 
     In accordance with one aspect of the present invention, antenna  108  can be manually manipulated to assume two or more positions to thereby place antenna  108  in a vertical orientation while still allowing convenient and comfortable use of the communication device. For example, FIG. 2 shows antenna  108  in a partially extended or “left handed” position, while FIG. 3 shows antenna  108  in a fully extended or a “right handed” position. More particularly, assume FIGS. 1-3 illustrate communication device  102  from the rear position, such that only the back of communication device  102  can be seen. The audio speaker and microphone (not shown) located on the front side of the communication device may be conveniently positioned proximate to a user&#39;s ear and mouth, respectively, while holding communication device  102  in a user&#39;s left hand; with antenna  108  in the partially extended position shown in FIG. 2, antenna  108  would assume a vertical orientation. On the other hand, when antenna  108  is in the fully extended position shown in FIG. 3, a user can conveniently hold communication device  102  using the right hand while maintaining antenna  108  in a substantially vertical disposition. 
     In accordance with a preferred embodiment of the present invention, when antenna  108  is in the partially extended position shown in FIG. 2, antenna  108  is at an angle  202  with respect to an arbitrary vertical line  204 ; when antenna  108  is placed in the fully extended position shown in FIG. 3, it assumes and angle  302  which respect to an arbitrary vertical line  304 . In a preferred embodiment, angles  202  and  302  are in the range of 10 to 80 degrees, and preferably in the range of 30 to 60 degrees, and optimally about 45 degrees. In accordance with an alternate embodiment of the invention, antenna  108  may be adjusted into any number of intermediate positions between the partially extended and the fully extended position. In this way, communication device  102  may be comfortably used by the user in virtually any position, while at the same time conveniently adjusting antenna  108  into a vertical orientation. 
     Referring now to FIGS. 4 and 5, a connector assembly  402  is configured to connect an antenna  408  and its associated connector arm  406  to a communication device (hereinafter referred to as a cellular telephone or simply cellular phone for simplicity). Connector assembly  402  suitably includes one or more tabs  410  disposed along a race  404 ; tab  410  and race  404  are desirably configured to be removably mounted to a mating connector member (not shown) on the cellular phone associated with antenna  408 . The particular mechanical attachment details of connector assembly  402  are beyond the scope of the present invention, and are discussed more fully in co-pending U.S. patent application Ser. No. 09/414,467 and entitled “Antenna Latching Mechanism”, filed in the names of Kevin House, Javier Leijo, Ronald Nordheus, Matthew Michieli, and Jay Mitchell (also assigned to Mototola, Inc. and corresponding to Motorola Docket No. CS10252). The entire contents of the foregoing co-pending patent application are hereby incorporated by this reference. 
     With continued reference to FIGS. 4 and 5, connector assembly  402  further comprises a printed wiring board (PWB)  412  having a board track  420  disposed on an upper surface  418  thereof. Board  412  may be conveniently secured to its cellular phone by using, for example, fastening holes  414  and  416 . With particular reference to FIG. 5, connector assembly  402  also includes an antenna connection circuit  520  and a tracer pin  502  disposed opposite board track  420 , as discussed in greater detail below in connection with FIGS. 6 and 7. 
     Referring now to FIGS. 6 and 7, antenna connection circuit  520  and board track  420  cooperate to form an RF interface which allows RF transmission back and forth between the antenna and the cellular phone. In a preferred embodiment of the present invention, this RF coupling circuit is concentric with the pivoting (or rotating) motion of connector assembly  402  (FIGS.  4  and  5 ). In this way, the rotating or pivoting mechanical motion of the antenna may be effectively leveraged to provide a position sensing function within connector assembly  402 , as described in greater detail below in connection with FIGS. 6-12. 
     More particularly, antenna connector circuit  520  shown in FIGS. 5 and 6 includes an RF conductor  602 , a shield  604 , and tracer pin  502 , also referred to as a sensing or sense pin. RF conductor  602  is configured to carry RF signals to and from antenna  408  (FIGS.  4 - 5 ). 
     With particular reference to FIG. 7, board track circuit  420  includes an RF conductor  702 , a shield  704 , and a sense track  706 . RF conductor  702  is suitably configured to carry RF signals to and from the cellular phone to which antenna  408  is connected, as described below in connection with FIGS. 11 and 12. 
     When PWB  412  is mated with antenna connector circuit  520  (FIGS.  4  and  5 ), RF conductor  602  contacts RF conductor  702 , placing them into electrical communication with one another. In similar fashion, shield  604  contacts shield  704 , forming an RF shield about respective RF conductors  602  and  702 , forming a mating coaxial or “COAX” conductor. When PWB  412  is placed into contact with antenna connector circuit  520 , for example when antenna  408  (FIGS. 4-5) is connected to its associated cellular phone, sense pin  502  of antenna connector circuit  520  is brought into proximity with sense track  706  (see FIG.  7 ). When pin  502  is in contact with track  706 , the position sensing circuit between the antenna and the cellular phone is completed, which permits the RF transmission circuit associated with the cellular phone to transmit RF signals to the antenna. The specific methods and structures for completing the RF connection between the antenna and the cellular phone are discussed in detail below in connection with FIGS. 11 and 12. 
     Referring again to FIGS. 6 and 7, it will be appreciated that while pin  502  is in contact with track  706 , the RF transmission circuit associated with the cellular phone is capable of transmitting RF signals to the antenna and receiving RF signals from the antenna. Conversely, when the pin is not in contact with its associated track, the RF transmission circuit associated with the cellular phone is set such that the cellular phone can no longer transmit. Moreover, in accordance with a preferred embodiment of the present invention, when the RF sensing pin is not in electrical contact with its associated sense track, either because the antenna has been rotated “out of position” or because the antenna assembly has been detached from the cellular phone, the RF transmission circuit associated with the cellular phone is disabled from transmitting RF signals at all. This is particularly advantageous in that it avoids the undesirable condition where the RF transmitting circuit associated with the cellular phone continues to transmit into what is essentially an open circuit, i.e., when the antenna is either removed or not properly configured for electrical communication with the RF transmission circuit. 
     In accordance with a further aspect of the present invention, the arc traversed by track  706  may be configured to correspond with the arc traversed by antenna  108  (see FIGS. 1-3) between the partially extended position (FIG. 2) and the fully extended position (FIG.  3 ). Indeed, by properly coordinating sense track  706  of FIG. 7 (or the alternate embodiment sense tracks discussed in connection with FIGS. 8-10) with the desired arc of travel for antenna  108 , communication device  102  can be configured to terminate RF transmission both when the antenna is removed form the device as well as when the antenna is not in proper position, i.e., when the sense pin is not properly in contact with its associated sense track. 
     Referring now to FIGS. 8-10, the range of travel of antenna  108  (FIGS. 1-3) during which the RF transmission circuit associated with communication device  102  is permitted to operate may be effectively controlled by the length (i.e., extent) and orientation of the sense track or sense tracks associated with PWB  412  (FIGS.  4 - 5 ). In this regard, a variety of options are available to extend the functionality of the present invention by employing one or more additional sense pins and/or one or more additional sense tracks. 
     More particularly and with specific reference to FIG. 8, a board track circuit  801  in accordance with an alternate embodiment of the present invention suitably comprises an RF conductor  802 , a shield  804 , and a sense track  806  (all of which are generally analogous to the corresponding components shown in FIG.  7 ). In accordance with the embodiment shown in FIG. 8, the antenna connector circuit (analogous to circuit  520  of FIG. 5) associated with the antenna coupling includes cooperating sensing pins  808 . In this embodiment, pins  808  are configured such that when the antenna is in its vertical or substantially vertical position, both pins contact the track. The sensing circuitry (described below in connection with FIGS. 11 and 12) associated with pins  808  may be configured to determine whether one or both of the pins are in contact with track  806 . For example, each of dual pins  808  may be suitably tied to electrical ground through a resistor, such that a first level of resistance is detected when one pin is in contact with a track, and a second level of resistance is detected when both pins are in contact with a track. In this way, the communication device can determine not only whether the antenna is in the vertical position, but the extent to which the antenna has deviated from the vertical position. In response to this information, the communication device could be configured to increase power or make other adjustments, as necessary, to accommodate the particular position of the cellular phone. In accordance with a further aspect of the present invention, when the antenna has deviated from a vertical position by a threshold amount, the communication device could be configured to alert the user, either through audible, optical, textual, or mechanical (e.g., vibrating) modalities to manipulate the communication device or the antenna to restore the antenna to a vertical or substantially vertical position. 
     With continued reference to FIG. 8, additional flexibility may be obtained by employing three or more pins (and, if desired, three or more corresponding resistors associated with the pins) to gather antenna position data of even finer granularity. For example, using three pins and three known resistance values (e.g., equal resistance values), the detection circuit could be configured to measure R/ 3  near the center of travel (corresponding to optimum vertical antenna position), R/ 2  for an area of travel near the center, and R at the edge of the allowed range of antenna position. In accordance with a further aspect of this embodiment, the antenna detection circuit could be configured to detect essentially an open circuit in an undesired range of antenna positions, for example corresponding to the antenna being moved impermissibly far from the vertical position or corresponding to the antenna being physically decoupled from its associated communications device. 
     Referring now to FIG. 9, multiple sense tracks may be employed. More particularly, a board track circuit  901  employing plural tracks suitably comprises an RF conductor  902 , a shield  904 , and a dual track assembly  906 . In accordance with the embodiment shown in FIG. 9, antenna connector circuit  520  (FIG. 5) advantageously comprises dual sense pins  908 . In this embodiment, the position detector circuit (shown in FIGS. 11 and 12) may be configured to sense a first resistance value when one of pins  908  is in contact with dual track  906 , and a second resistance value when both pins  908  are in contact with dual track  906  (a third resistance value, for example an open circuit or a closed circuit, could also represent the condition when neither of dual pins  908  are in contact with dual track  906 ). 
     Referring now to FIG. 10, a further alternate embodiment of the present invention comprises a board track circuit  1001  including an RF conductor  1002 , a shield  1004 , and concentric opposing arcs  1006 . In this embodiment, antenna connector circuit  520  (FIG. 5) advantageously includes dual pins  1008 . Depending on the length of one or both of arcs  1006  and the relative positions of pins  1008 , the position sensing circuit may be conveniently configured to detect when neither, one or both pins  1008  are in contact with dual track  1006 , thereby providing precise antenna position information to the RF transmission circuit. 
     Referring now to FIG. 11, a hybrid RF/DC coupling circuit  1101  suitably comprises an antenna circuit  1105  associated with antenna  108 , an antenna/communication device interface circuit  1103 , an RF circuit  1107 , and a host processor circuit  1109 . In general, antenna circuit  1105  is integral with antenna  108 ; in a preferred embodiment, antenna circuit  1105  is connected to antenna  108  either directly or through connector arm  106  (FIG.  1 ). In a particularly preferred embodiment, antenna circuit  1105  generally corresponds to antenna connector circuit  520  and sense pin  502  (FIGS. 5-6) in its overall function. It will also be appreciated that many of the pin configurations of the alternate embodiments discussed in FIGS. 8-10 may also be embodied in antenna circuit  1105  as desired. 
     With continued reference to FIG. 11, interface circuit  1103  is generally analogous to board  412  of FIGS. 4 and 5 in its overall function. That is, interface  1103  advantageously provides electrical communication between antenna circuit  1105  and RF circuit  1107  and activates sense pin when the antenna is within its desired range of positions. As discussed above, in accordance with one aspect of the present invention, interface circuit  1103  is configured to prevent RF transmission between the antenna and its associated cellular phone when the antenna assembly is either removed from the cellular phone or when the antenna is not within its desired range of positions. In this regard, it would be understood that interface circuit  1103  may embody board track  420  (FIG. 4) or one of the other various alternate board track embodiments discussed above in connection with FIGS. 8-10, as desired. 
     RF circuit  1107  comprises a transceiver circuit  1118  (comprising both a transmission circuit and a receiving circuit), an isolation capacitor  1120 , a resistor  1122 , a comparator  1124 , and an output  1125 . As described below in greater detail, comparator  1124  is configured to compare an input DC signal to a desired reference DC value and output a binary signal representative of the state of antenna  108 . More particularly, comparator  1124  is configured to output a logic high value when antenna  108  is attached to the cellular phone and within its permitted range of motion, and to output a logic low value when the antenna is either removed from the cellular phone or outside its operating range. In the embodiment shown in FIG. 11, output  1125  is configured to transmit a binary signal to an input  1128  associated with host processor circuit  1109 . Upon determining the state of antenna  108 , host processor circuit  1109  suitably transmits an appropriate control signal to RF transceiver circuit  1118  through any convenient conductive path (not shown). In response, RF transceiver circuit  1118  is enabled to transmit and receive RF signals when the output of comparator  1124  indicates that antenna  108  is connected to the cellular phone and properly positioned; conversely, transceiver circuit  1118  is configured to terminate RF transmission when the output of comparator  1124  indicates that antenna  108  is either decoupled from the cellular phone or otherwise out of its desired range of operating positions. In an alternate embodiment, comparator  1124  may be configured to apply a control signal, for example a binary logic signal, directly to transceiver circuit  1118 . 
     With continued reference to FIG. 11, a coaxial (or coax) conductor  1108  is suitably configured to carry RF signals between antenna  108  and RF circuit  1107 . More particularly, antenna circuit  1105  comprises an RF contact  1102 , a ground contact  1104 , and a shield  1106  as is conventional in the art. 
     Antenna circuit  1105  further comprises a sensing circuit  1111  which includes a switch  1110 , a capacitor  1112 , a resistor  1114 , and a grounded shield  1116  (which may suitably be co-extensive with shield  1106 ). It will be appreciated that switch  1110  generally corresponds in its overall function to pin  502  shown in FIG. 5, as well as the analogous pins discussed in connection with FIGS. 8-10. Moreover, coax conductor  1108  and shield  1116  are generally analogous in function to RF conductor  602  and shield  604 , respectively, as discussed above in connection with FIG. 6 (as well as the analogous RF conductors and shields discussed in connection with FIGS.  8 - 10 ). Consequently, the condition in which switch  1110  is in the closed position corresponds to pin  502  being an electrical communication with track  706  as discussed above in connection with FIG. 7 (and as also discussed in connection with the alternative embodiments described above in conjunction with FIGS.  8 - 10 ). Conversely, the open position of switch  1110  corresponds to the situation in which the sensing pin is not in contact with its associated track. 
     In accordance with an alternate embodiment of FIG. 11, sensing circuit  1111  could be configured to include a plurality of switches and one or more additional resistors to accommodate the multiple pin and multiple track embodiments discussed above in connection with FIGS. 8-10. 
     Referring now to FIGS. 11 and 12, the operation of hybrid RF/DC coupling circuit  1101  will now be described in greater detail. 
     Referring now to FIG. 12, an electrical schematic diagram illustrates a preferred implementation of a switching circuit and a comparator circuit for use in connection with the hybrid circuit of FIG.  11 . More particularly, a hybrid circuit  1201  suitably comprises a coaxial conductor  1208  configured to transmit RF signals between an antenna  1226  and an RF transceiver circuit  1218 . Hybrid circuit  1201  further comprises a switch  1210 , a capacitor  1212 , a resistor  1216 , respective isolation capacitors C 3  and C 4 , one or more (preferably coextensive) grounded shields  1216 , a resistor  1222 , and a comparator circuit  1224 . Comparator circuit  1224  is suitably configured to generate an output signal  1232 , for example a binary signal indicative of the state or position of antenna  1226  (analogous to that described above in connection with output  1125  in FIG.  11 ), and to apply output signal  1232  to transceiver  1218 . In this way, if antenna  1226  is either disconnected from the cellular phone or not in its proper position, hybrid circuit  1201  can detect this condition and instruct transceiver circuit  1218  to terminate RF transmission, as desired. In accordance with a further aspect of the present invention, hybrid circuit  1201  is capable of carrying a DC signal indicative of the state of position of antenna  1226  as well as the RF signal transmitted from and received by antenna  1226  on a single coax conductor, namely, coax conductor  1208 . 
     With continued reference to FIG. 12, the high frequency RF signals (typically in the range of 900 megahertz (MHz) to 2 gigahertz (GHz)) readily pass through isolation capacitors  1220  and  1204 , in view of the fact that capacitors  1220  and  1204  present a relatively low or even imperceptible impedance to the high frequency RF signals. Thus, capacitors  1220  and  1204  essentially function as high pass filters, allowing the RF signals to pass therethrough, yet at the same time block the relatively low switching frequency associated with switch  1210 . In this regard, the switching frequency will necessarily be quite low, inasmuch as it is required to bring the antenna into and out of its permissible range of positions in order to open and close switch  1210 . Capacitors  1204  and  1220  are suitably in the range of 10 picofarads (pF) to 100 pF. 
     Moreover, the relatively high impedance associated with resistors  1214  and  1222  prevent the RF signals from entering into either comparator circuit  1224  or from crossing resistor  1214 , as discussed in greater detail below. 
     Capacitors  1220  and  1204  also essentially filter the low frequency switching noise and prevent the low frequency signal from entering transceiver circuit  1218  or antenna  1226 . 
     Comparator circuit  1224  suitably comprises an amplifier  1228 , a capacitor  1230 , and a resistor  1232 . Amplifier  1228  suitably comprises a comparator, for example a part number 1M  106  available from the National Semiconductor corporation. However, the term comparator is used in a functional manner. Amplifier  1228  may comprise solely a single transistor. In the preferred embodiment, two transistors are used; one transistor to compare the signals and one transistor to invert the output. In accordance with the illustrated embodiment, a predetermined reference voltage (for example ¾ of supply voltage which is 3 volts in preferred embodiment) is applied to the positive terminal of amplifier  1228 , with the negative terminal being connected to conductor  1234 . A supply DC voltage (DCV) is suitably applied across resistor  1232 . Hence, when switch  1210  is open, voltage DCV is presented at the negative input terminal to amplifier  1228 . In the preferred embodiment, the reference voltage (V r ) applied to the positive terminal of amplifier  1228  is suitably smaller than the DCV voltage applied to the negative terminal of amplifier  1228  when switch one is open. In this state, the operational amplifier is configured to generate an output  1232  which is a logical low value, indicating to transceiver circuit  1218  that antenna  1226  is either not connected to the cellular phone or is not within its permissible range of positions. In response, transceiver circuit  1218  is disabled from transmitting RF signals. In accordance with one aspect of the present invention, it is advantageous to disable the transmitter associated with the communications device when the antenna is either missing or not in its proper position, to both conserve power and reduce wear and possibly even damage on RF transceiver circuit  1118  (see FIG.  11 ). 
     It will also be understood that when switch  1210  is open, no current flows through resistors  1222  and  1214  (defined as a DC path  1202 ) inasmuch as open switch  1210  essentially presents a DC open circuit between resistors  1222  and  1214  and ground. When switch  1210  is closed, a current path to ground is provided to supply voltage DCV through resistor  1232 , resistor  1222 , resistor  1214 , and switch  1210 . When switch  1210  is in the closed position, the voltage applied to the negative input of amplifier  1228  is reduced to the following value: 
     
       
           V   s   =DCV ( R   1   +R   2 )/( R   1   +R   2   +R   3 ) 
       
     
     Where R 1 , R 2  and R 3  correspond to the resistances associated with resistors  1214 ,  1222 , and  1232 , respectively. The values of supply voltage DCV and of resistors  1214 ,  1222 , and  1232  are also selected so that the foregoing voltage division results in a voltage level at the negative input of amplifier  1228  which is now less than the reference voltage applied to the positive input of amplifier  1228 . Consequently, output  1232  of amplifier  1228  changes state, i.e., output  1232  goes to a logical high value, indicating that switch  1210  is closed and further indicating that antenna  1226  is within its desired range of operating positions. 
     When antenna  1226  is subsequently removed from its cellular phone or is moved out of its permissible operating position, switch  1210  opens, and the voltage level at the negative input of amplifier  1228  jumps above the reference voltage applied to the positive terminal of amplifier  1228 , causing output  1232  to again go to a logic low level. 
     In accordance with a further aspect of the present invention, the ability of coax  1208  to simultaneously transmit the DC switching signal and the RF signal is further enhanced by the presence of capacitors  1212  and  1230 . More particularly, capacitors  1212  and  1230  present a low reactance to the RF signal, thereby keeping the RF signal out of the DC circuits. In particular, the reactance of a capacitor is given by: 
     
       
           X (reactance)={fraction (1/27)}π fC   
       
     
     Where f corresponds to the frequency seen by the capacitor, and C is the capacitor&#39;s capacitance. By presenting a low reactance to the RF signals, capacitors  1212  and  1230  effectively shunt any spurious RF signals to ground, keeping them out of the DC circuitry. 
     Thus, it is apparent that there has been provided, in accordance with the invention, methods and structures for sensing the position of an antenna and transmitting a DC signal indicative of that position to the host communication device along the same RF coax conductor which the antenna and communications device use to communicate RF signals. Although the invention has been described with reference to the illustrated and alternate embodiments, it is not intended that the invention be so limited. For example, while the sensing pin (or pins) has been described as being located on the antenna circuit and the sensing track has been described as being located on the communications device side of the antenna/communications device interface, the invention would work equally well if the locations of the track and sensing pin were inverted. In addition, the sensing pin has been described as being in contact with the sensing track when the antenna is in the correct position and not in contact with the sensing track when the antenna is not in the correct position. These two states could be reversed with no change in functionality. Moreover, although the sense pin (or pins) have been described as being connected to the coax line through a resistor, the various sensing devices could also be capacitively or inductively coupled to the sensing circuit, as desired. In addition, although the invention has been described in connection with arced sensing circuits located concentrically with respect to the antenna pivot point, the invention could also be implemented in the context of a sliding (e.g., linear) antenna, or in virtually any sensing paradigm such as elliptical or serpentine, and need not be concentric or even in an arced configuration so long as antenna position information can be effectively conveyed to the host communications device in accordance with the principles set forth above in the context of the coupling circuit and the hybrid circuits of FIGS. 11 and 12, respectively. In addition, although the output of comparator circuit  1224  is described as being in a logical high state when the antenna is properly positioned and being in a logical low state when the antenna is not properly positioned, these logical values are arbitrary designations and could be inverted, as desired. While comparator circuit  1124  and RF transceiver circuit  1118  are shown in FIG. 11 as occupying the same board, there is no change in functionality if they are on different boards, so long as they are still electrically connected in the same manner. These and other changes, modifications, and substitutions can be made to the various components and method steps described herein without departing from the spirit and scope of the present invention as set forth in the appended claims.