The present invention relates to radio communications, and more particularly, to radio communications antennas and radio communications devices incorporating the same.
Wireless terminals, such as cellular telephones and wireless-capable laptop computers and personal digital assistants (PDAs), are now commonly designed to operate in multiple frequency ranges. For example, many cellular telephones are now designed for dual-band or triple-band operation in GSM and CDMA modes at nominal frequencies of 850 MHz, 900 MHz, 1800 MHz and/or 1900 MHz. It is also becoming desirable for such devices to also provide service in other bands, such as the bands used for GPS (Global Positioning Service) and Bluetooth wireless ad hoc networking.
Multiple antennas with separate feedpoints are commonly used to provide such multi-band capabilities. For example, the SonyEricsson T206 model wireless phone includes two separate antennas, one for the 850/1900 MHz bands and one for GPS; the Sony Ericsson model Z1010 phone has one antenna that works at GSM900/1800/UMTS (the frequency range of UMTS is 1920-1980 MHz for transmitting and 2110-2170 MHz for receiving) and a separate antenna for Bluetooth communications; the SonyEricsson model T68i phone has one antenna for 900/1800/1900 MHz and a separate antenna for Bluetooth communications; and the SonyEricsson T616 phone has respective separate antennas for 850/1800/1900 MHz and Bluetooth.
In light of the increasing number of frequencies over which wireless terminals are expected to operate, there is a need for antennas that provide desirable operating characteristics in multiple frequency bands.
In some embodiments of the present invention, a radio communications antenna includes a ground plane and a conductor loop overlying the ground plane. A monopole extends off the ground plane, and the monopole and the conductor loop are configured to be coupled at a common feedpoint. In some embodiments of the present invention, the conductor loop has a reflective feature, such as a corner, therein.
In further embodiments of the present invention, the conductor loop is rectangular. The conductor loop may be arranged substantially parallel to the ground plane, and the monopole may be substantially parallel to the conductor loop. The monopole may be coupled to the conductor loop at a corner thereof. In some embodiments, the ground plane, the conductor loop and the monopole may be configured to provide a voltage standing wave ratio (VSWR) less than about 3 over a frequency range from about 1.5 GHz to about 2.5 GHz.
In further embodiments of the present invention, the conductor loop is positioned adjacent an edge of the ground plane, and the monopole extends off the edge of the ground plane. The ground plane may comprise a conductive layer on a printed circuit substrate. The common feedpoint may comprise a pad on the printed circuit substrate.
According to still further embodiments of the present invention, an antenna may further include a helical element arranged coaxial with the monopole and coupled to the common feedpoint. The ground plane, the conductor loop, the monopole and the helical element may be configured to provide a voltage standing wave ratio (VSWR) less than about 3 over a frequency range from about 1.5 GHz to about 2.5 GHz and a VSWR less than 3 over a frequency range from about 800 MHz to about 900 MHz. In some embodiments, the monopole comprises a retractable monopole configured to extend and retract through the helical element and configured to connect to the common feedpoint in an extended position. The helical element may be configured to disconnect from the common feedpoint when the retractable monopole is in the extended position and configured to connect to the common feedpoint to the common feedpoint when the retractable monopole is in a retracted position.
In some embodiments of the present invention, the ground plane comprises a rectangular ground plane, the conductor loop comprises a rectangular conductor loop having a side substantially aligned with a shorter side of the rectangular ground plane, and the monopole comprises a substantially linear conductor that extends substantially perpendicular to the edge of the ground plane from a coupling point at a corner of the rectangular conductor loop at the edge of the ground plane. In certain embodiments, the conductor loop has dimensions of about 18 mm by about 8 mm, has a longer side thereof substantially aligned with the edge of the ground plane, and is separated from the ground plane by a distance in a frequency range from about 5 mm to about 10 mm, and the monopole has a length of about 36 mm. The ground plane may comprise a substantially rectangular ground plane having a length greater than about 110 mm and a width greater than about 40 mm. A helical element may be wrapped around the monopole and coupled to the common feedpoint.
According to other embodiments of the present invention, a radio communications device comprises a frame, a radio communications circuit supported by the frame, and a conductive ground plane supported by the frame. A conductor loop is supported by the frame and overlies the ground plane. A monopole is supported by the frame and extends off the ground plane. The monopole and the conductor loop are configured to be coupled to the radio communications circuit at a common feedpoint. The conductor loop may have a reflective feature therein, e.g., the conductor loop may be rectangular. The ground plane, the conductor loop and the monopole may be configured to provide a voltage standing wave ratio (VSWR) less than about 3 over a frequency range from about 1.5 GHz to about 2.5 GHz. A helical element may be arranged coaxial with the monopole and coupled to the common feedpoint, and the ground plane, the conductor loop, the monopole and the helical element may be configured to provide a voltage standing wave ratio (VSWR) less than about 3 over a frequency range from about 1.5 GHz to about 2.5 GHz and a VSWR less than 3 over a frequency range from about 800 MHz to about 900 MHz.
In further embodiments, the frame comprises a clamshell housing having first and second rotatably coupled portions, and the ground plane may comprise electrically coupled first and second portions disposed in respective ones of the first and second housing portions. The first and second housing portions may be mechanically joined by a hinge, and the monopole and the helical element may be positioned between the first and second housing portions and aligned substantially parallel to an axis of rotation of the hinge.
According to additional embodiments of the present invention, a radio communications device comprises a frame, a radio communications circuit supported by the frame, and an antenna electrically coupled to the radio communications circuit, supported by the frame and comprising commonly fed conductor loop, monopole and helical elements. The conductor loop element may have a reflective feature therein, e.g., the conductor loop element may comprise a rectangular conductor loop. The device may further comprise a ground plane supported by the frame, and the conductor loop element may be positioned overlying the ground plane. The ground plane, the conductor loop element, the monopole element and the helical element may be configured to provide a voltage standing wave ratio (VSWR) less than about 3 over a frequency range from about 1.5 GHz to about 2.5 GHz and a VSWR less than 3 over a frequency range from about 800 MHz to about 900 MHz.
Specific exemplary embodiments of the invention now will be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like numbers refer to like elements. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present.
Reference now is made to
As can be seen in
Still referring to
When the retractable monopole 1310 is in the retracted position (
The retractable monopole 1310 may comprise a quarter-wave monopole (e.g., for 850 or 900 MHz band), while the helical element 1330 may be dual-band for 850/1900 MHz or 900/1800 MHz bands. The combination of the monopole 1310, the loop 1320 and the helical element 1330 may be used for a combination of 850/1800/1900/UMTS/BT bands or a combination of 900/1800/1900/UMTS/BT bands. The dimensions of the loop 1320 may be similar to those of the loop of
In the drawings and specification, there have been disclosed exemplary embodiments of the present invention. Although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined by the following claims.
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