Abstract:
A hybrid antenna and integrated proximity sensor is described wherein a commonly shared conductive structure is used for both antenna functions as well as a proximity sensor functions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of priority with U.S. Provisional Ser. No. 62/090,887, filed Dec. 12, 2014; the contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to the field of wireless communication; and more particularly, to wireless communication networks and antenna array techniques for interference suppression and multipath mitigation. 
         [0004]    2. Description of the Related Art 
         [0005]    Proximity sensors are in use today in commercial wireless devices as well as other product groups, and are used for a wide variety of applications. For example, it is common for a proximity sensor to be integrated into a cell phone, with the proximity sensor used to sense when the display region of the cell phone is in close proximity to an object. This sensing of an object being close to the display is used to reduce battery power consumption by turning off or down the brightness of the display when the display is in close proximity to a user&#39;s head or the display is covered by an object. 
         [0006]    Another application of a proximity sensor is to integrate the sensor into a tablet computing device and use the sensor to sense proximity of the user&#39;s body to the tablet. When the user&#39;s body is close to the tablet, the transmit power of the cellular transceiver is reduced to allow the tablet to meet an acceptable threshold for Specific Absorption Rate (SAR). 
         [0007]    One implementation of a proximity sensor is a capacitive sensor, and is effectively a parallel plate capacitor. A dielectric material is positioned between two plates of the capacitor to provide support and maintain a set separation distance between the plates. Two conductors are used to connect the two plates to a circuit that monitors capacitance. As objects are placed in proximity to the capacitor the objects interact with the fringing electric field emanating from the region between and external to the plates. This interference with the fringing fields of the capacitor translates into a change in capacitance, which can be detected. 
       SUMMARY OF THE INVENTION 
       [0008]    A proximity sensor can be positioned beside or beneath an antenna and the antenna can be re-tuned to compensate for the effect of placing the metal conductors near the antenna. A more efficient method in terms of maintaining antenna performance, reducing volume required, and saving cost is to design the proximity sensor into the antenna structure. This combination antenna and proximity sensor will provide a more optimized and cost effective solution for devices that require antennas and proximity sensing systems. More importantly, by designing the proximity sensor, or multiple proximity sensors into the antenna, the ability to detect changes to the environment in the region of the antenna can be improved. This is important, since it is desirable to know when objects are positioned close to the antenna. Sensing when objects are in close proximity to an antenna can assist in re-tuning the antenna and keeping the antenna impedance optimized. 
         [0009]    A hybrid antenna is disclosed herein which is configured to use a portion of the antenna structure itself as a sensing component (proximity sensor). Thus, the hybrid antenna conductor is used as an antenna and a sensing component. This hybrid antenna and sensing component is able to reduce the complexity of hybrid antenna design and also reduced the cost as no additional sensing component is needed. 
         [0010]    The sensing circuit is coupled to the hybrid antenna/sensing component conductor through a low pass filter. The antenna transmitter/receiver is coupled to the hybrid antenna/sensing component conductor with a coax cable through a high pass or band pass filter. In this configuration, the conductor is capable of acting as both an antenna and a sensing component. 
         [0011]    Traditionally in a tablet, two sensor pads are needed at two opposite sides of the antenna to detect object proximity. With this traditional two-sensor architecture there is a possibility that the detection is missed, for example, where the object is in between the two sensor pads. However, with the disclosed hybrid antenna and sensing component this detection will definitely not be missed as the antenna itself is also the sensor component. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  shows a hybrid antenna and sensing component in accordance with an embodiment. 
           [0013]      FIG. 2  shows a hybrid antenna and sensing component in accordance with another embodiment. 
           [0014]      FIG. 3  shows a hybrid antenna and sensing component in accordance with another embodiment. 
           [0015]      FIG. 4  shows a hybrid antenna and sensing component in accordance with yet another embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0016]    In the following description, for purposes of explanation and not limitation, details and descriptions are set forth in order to provide a thorough understanding of the embodiments of the invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments, including certain variations or alternative combinations that depart from these details and descriptions. The following description is provided in order to enable those having skill in the art to make and use the preferred embodiment(s) of the invention. 
         [0017]    Now turning to the drawings,  FIG. 1  shows a hybrid antenna and sensing component in accordance with an embodiment. The hybrid antenna and sensing component comprises an elongated conductor  11  coupled to a transceiver circuit  41  via a coaxial cable  22  extending therebetween. A first filter  21  is positioned between the elongated conductor  11  and the transceiver  41 . The first filter  21  may include: a high pass filter, a band pass filter, or a combination thereof. The transceiver  41  (receiver, transmitter, or combination) is also coupled to a control circuit  33  which is further coupled to a sensing circuit  32 . The sensing circuit  32  is further coupled to a low pass filter  31  and the elongated conductor  11 . The filters  21 ;  31  are used to isolate radiofrequency (RF) signals from proximity signals. RF signals are typically between 700 MHz and 5 GHz, depending on the application (cellular, Wi-Fi, etc.). Proximity signals are typically about 100 KHz. Thus, the elongated conductor  11  is used as both an antenna and a sensing circuit, with the filters  21 ;  31  configured to separate the RF from proximity signals. Note the various components of the hybrid antenna and sensing component can be connected by a wire or trace  5  as shown. 
         [0018]    Other alternative configurations may be implemented and readily appreciated by those having skill in the art. 
         [0019]    For example,  FIG. 2  shows a hybrid antenna and sensing component in accordance with another embodiment. The antenna and sensing component is similar to that shown in  FIG. 1 , with the addition of a second high pass filter  51  (or other high pass circuit or active circuit) positioned on the elongated conductor for restricting the extent of the proximity sensor portion of the conductor. The conductor is shown having two portions, a first portion  11   a  and a second portion  11   b.  The second high pass filter  51  is positioned between the first and second portions of the elongated conductor. Here, the length of the sensing conductor is limited at the second high pass filter wherein the radiating antenna portion extends the entire length of the conductor  11   a;    11   b  across the second high pass filter. Where the high pass filter is an active circuit, one or more optional control lines  55  (shown in broken lines) can be provided for controlling the circuit. The control lines can be coupled to one or both of the transceiver circuit and/or control circuit for actively configuring a length of the proximity sensor. Note that if the second high pass filter  51  is not an active circuit (ex: is a conventional high pass filter), only the high frequency signals will continue through the second high pass filter along the entire length of the elongated conductor. In this regard, the hybrid antenna and sensing component is configured such that the antenna utilizes the entire length of the elongated conductor whereas the sensing component utilizes only a portion (L 1 ) of the elongated conductor. 
         [0020]      FIG. 3  shows a hybrid antenna and sensing component in accordance with another embodiment. The antenna is similar to that of  FIG. 1  but further includes an active circuit  61  disposed between a first end and a second end of the elongated conductor. The active circuit is configured to restrict the extent of the sensor as a function of time by varying a reactance or switching to shorten a length of the elongated conductor from a second length L 2  ( 11   a  plus  11   b ) to a first length L 1  ( 11   a  only). In time slot A the length of the conductor extends from a first end to a second end (L 2 ). However, in time slot B the length of the conductor extends from the active circuit  61  to the second end (L 1 ). The active circuit can be controlled by one or more control lines  65  coupled to the transceiver circuit  41 , control circuit  33 , or both. 
         [0021]      FIG. 4  shows a hybrid antenna and sensing component in accordance with yet another embodiment. Here, an elongated conductor having a first portion  11   a  and a second portion  11   b  is coupled to a transceiver circuit  41  using a coaxial cable  22 . A first filter  21 , including a high pass filter, band pass filter, or combination thereof, is positioned between the elongated conductor  11   a;    11   b  and the transceiver  41 . The elongated conductor is coupled to a first control circuit  33   a  at a first end thereof, wherein a first low pass filter  31   a  and a first sensing circuit  32   a  are disposed between the first end of the elongated conductor  11   a  and the first control circuit  33   a  along the transmission path or trace  5 . The elongated conductor is further coupled to a second control circuit  33   b  at a second end thereof, wherein a second low pass filter  31   b  and a second sensing circuit  32   b  are each disposed between the second portion of the elongated conductor  11   b  and the second control circuit  33   b  along the transmission path or trace. Each of the first and second control circuits  33   a;    33   b  is coupled to the transceiver circuit  41 . A second high pass filter  51  (or high pass circuit or active circuit) is positioned along the conductor between the first and second portions  11   a;    11   b,  respectively. In this regard, the antenna and sensing component comprises two distinct sensing sections on either side of the second high pass circuit  51  (or active circuit). RF signals and proximity signals are filtered using the high pass and low pass filters as shown. The result is a hybrid antenna and sensing component with two distinct sensors configured to share a volume of the antenna. Where the second high pass filter includes an active circuit, control signals can be sent from the transceiver circuit (or other control circuit) through an optional control line  55 . Where the second high pass filter is a conventional filter, no control line is required. 
         [0022]    While various embodiments and arrangements have been illustrated, it should be recognized by those having skill in the art that other variations and alternative arrangements of the disclosed features and embodiments can be similarly implemented to obtain an antenna with integrated sensing component. Accordingly, the above descriptions are not intended to limit the spirit and scope of the invention as set forth in the claims.