Patent Application
20150084829
Electronic devices, such as portable communication devices, continue to diminish in size. All such portable communication devices use some type of antenna for transmitting and receiving communication signals. Antennas and antenna systems generally fall into two categories, directional antennas and non-directional (also referred to as omni-directional) antennas. As its name implies, a directional antenna is one that exhibits a radiation pattern that is stronger in one direction than in another. An omni-directional antenna is one that exhibits a radiation pattern that is substantially the same regardless of direction. In some operating circumstances, it may be desirable to employ an omni-directional antenna, while in other operating circumstances, it may be desirable to employ a directional antenna.
Integrating a directional antenna and an omni-directional antenna in a single wireless device poses challenges including antenna location, orientation, polarization, and other factors. Further, it is also challenging to integrate into a wireless device switching circuitry that can select between the two antennas.
In the figures, like reference numerals refer to like parts throughout the various views unless otherwise indicated. For reference numerals with letter character designations such as “102a” or “102b”, the letter character designations may differentiate two like parts or elements present in the same figure. Letter character designations for reference numerals may be omitted when it is intended that a reference numeral encompass all parts having the same reference numeral in all figures.
The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.
In this description, the term “application” may also include files having executable content, such as: object code, scripts, byte code, markup language files, and patches. In addition, an “application” referred to herein, may also include files that are not executable in nature, such as documents that may need to be opened or other data files that need to be accessed.
The term “content” may also include files having executable content, such as: object code, scripts, byte code, markup language files, and patches. In addition, “content” referred to herein, may also include files that are not executable in nature, such as documents that may need to be opened or other data files that need to be accessed.
As used in this description, the terms “component,” “database,” “module,” “system,” and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device may be a component. One or more components may reside within a process and/or thread of execution, and a component may be localized on one computer and/or distributed between two or more computers. In addition, these components may execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the Internet with other systems by way of the signal).
As used herein, the terms “transducer” and “transducer element” refer to an antenna element that can be stimulated with a feed current to radiate electromagnetic energy, and an antenna element that can receive electromagnetic energy and convert the received electromagnetic energy to a receive current that is applied to receive circuitry.
As used herein, the term “orthogonal” refers to lines, line segments, or electric fields that are perpendicular at their point of intersection.
As used here, the term “orthogonal electric fields” refers to the orientation of two electric fields that are perpendicular to each other.
As used herein, the term “dual polarization” refers to an antenna that generates two electric fields and that has two components that are orthogonal to each other.
As used herein, the term “linear polarization” refers to an electric field vector or magnetic field vector that travels along a given plane along the direction of propagation. The orientation of a linearly polarized electromagnetic wave is defined by the direction of the electric field vector. For example, if the electric field vector is vertical (alternately up and down as the wave travels) the radiation is said to be vertically polarized.
As used herein, the term “circular polarization” refers to an electric field vector that, at a given point in space, describes a circle as time progresses. If the wave is frozen in time, the electric field vector of the wave describes a helix along the direction of propagation.
As used herein, the term “directional antenna” is one that exhibits a radiation pattern that is stronger in one direction than in another.
As used herein, the term “omni-directional antenna” is one that exhibits a radiation pattern that is substantially the same regardless of direction.
The multiple antenna system for a wireless device includes an omni-directional antenna and a directional antenna, and can be incorporated into or used with a communication device, such as, but not limited to, a wireless device referred to as an industrial fixed beacon (iFB), or another wireless device it which it is desirable to have both an omni-directional antenna and a directional antenna.
The elements 521 and 522 of the first antenna 501 are located close to the edge of the PWB 502 and form “slots” 510a and 510b located between the elements 521 and 522 and the ground plane 504. The slots 510a and 510b allow the first antenna to operate in what is referred to as a “slot mode.” The first antenna is generally referred to as being “linearly polarized.” However, the “slot mode” operation allowed due to the configuration of the first antenna 501 relative to the ground plane 504 allows the first antenna to exhibit “circular polarization” characteristics, and is considered to be “circularly polarized.” The circular polarization is created when the dipole elements 521 and 522 generate the polarization of the electric field in the axis that is parallel to the orientation of the dipole elements 521 and 522, in this case, it is in the X axis, illustrated using reference numeral 535. Then the slot mode generates the polarization of the electric field in the axis that is vertical to the slot orientation, in this case it is on the Y axis, which is the axis on which the centerline 515 lies. As a result, the two components of the electric field are orthogonal to each other, resulting in the circular polarization. A stepped impedance matching feature 524, which can appear as a “zigzag” feature of the dipole element 522 is also used to control the axial ratio, which is a factor that determines the extent of the circular polarization. The first antenna 501 includes a feed 513 located near the line 515 approximately as shown.
The second antenna 503 is “circularly polarized” and includes a feed 512 also located near the line 515 approximately as shown. Locating the feed 513 of the first antenna 501 and the feed 512 of the second antenna 503 close to each other and close to the line 515 minimizes antenna coupling between the first antenna 501 and the second antenna 503. In an embodiment, the distance between the feed 512 and the feed 513 can be approximately 10 millimeters (mm) to 25 mm.
The first antenna 501 and the second antenna 503 are also formed so as to have respective major surfaces that reside in the same plane, which is also the plane having the major surface of the ground plane 504.
The elements 821 and 822 of the first antenna 801 are located close to the edge of the PWB 802 and form “slots” 810a and 810b located between the elements 821 and 822 and the ground plane 804. The slots 810a and 810b allow the first antenna 801 to operate in what is referred to as a “slot mode.” The first antenna is referred to as being “circularly polarized.” As mentioned above, the circular polarization of the first antenna 801 results from the combination of the slot mode and the ordinary linear polarization of the dipole mode. The circular polarization of the first antenna 801 results from the ordinary single element dipole antenna combined with the hidden “slot mode” operation resulting from the slots 810a and 810b. The circular polarization of the first antenna 801 is created by the orthogonality between the electric field from the slots 810a and 810b and the electric field from the dipole elements 821 and 822.
The first antenna 801 also includes an impedance matching feature 824. In an embodiment the impedance matching feature 824 comprises a “meander” “stepped” or a “zig-zag” structure, which performs antenna impedance matching by creating capacitive and inductive coupling. Controlling the capacitive and inductive coupling for the first antenna 801 allows effective impedance matching for the first antenna 801. The meander pattern of the impedance matching feature 824 contributes to impedance matching because the meander pattern behaves as an inductor, while the gap between the impedance matching feature 824 and the other dipole element 822; and the gap between the impedance matching feature 824 and the ground plane 804 will behave as a capacitor.
Further, the impedance matching feature 824 also influences, to some extent, the axial ratio, which is a factor that determines the degree of circular polarization. The axial ratio depends, at least in part, on the size of the ground plane and the slot gap distance defined between the lower edge of the dipole elements 821 and 822 and the upper edge of the ground plane 804, which in an exemplary embodiment, can be 2.8 mm In an exemplary embodiment, the impedance matching feature 824 will connect directly to a radio frequency(RF) front end circuit in the controller 825 over, for example, connection 823, and the dipole element 822 will connect directly to the ground plane 804.
The dimensions shown in
The second antenna 903 is printed as shown and is configured to be “circularly polarized.” The dimensions shown in
The baseband subsystem 1010 generally includes a processor 1002, which can be a general purpose or special purpose microprocessor, memory 1014, application software 1004, analog circuit elements 1006, and digital circuit elements 1008, coupled over a system bus 1012. The system bus 1012 can comprise the physical and logical connections to couple the above-described elements together and enable their interoperability.
An input/output (I/O) element 1016 is connected to the baseband subsystem 1010 over connection 1024 and a memory element 1018 is coupled to the baseband subsystem 1010 over connection 1026. The I/O element 1016 can include, for example, a microphone, a keypad, a speaker, a pointing device, user interface control elements, and any other devices or system that allow a user to provide input commands and receive outputs from the wireless device 1000.
The memory 1018 can be any type of volatile or non-volatile memory, and in an embodiment, can include flash memory. The memory 1018 can be permanently installed in the wireless device 1000, or can be a removable memory element, such as a removable memory card.
The wireless device 1000 may also include a metal sensor 1022 coupled to the baseband subsystem 1010 over connection 1028. The metal sensor 1022 can detect the presence of metal or metallic objects in the vicinity of the wireless device 1000 and cause the wireless device 1000 to use one or more of the exemplary embodiments of the directional antenna and the omni-directional antenna described herein. For example, the metal sensor 1022 may provide an impedance measurement that can be interpreted by the processor 1002, which can then control the front end module 1050 to select any of the first antenna 1060 and the second antenna 1065 in response to the signal from the metal sensor 1022. The processor 1002, the memory 1014 and the application software 1004 may comprise a controller 1025, or perform a controller function to control the switch 1055 to select the appropriate antenna based on location, operating conditions, or other factors.
The processor 1002 can be any processor that executes the application software 1004 to control the operation and functionality of the wireless device 1000. The memory 1014 can be volatile or non-volatile memory, and in an embodiment, can be non-volatile memory that stores the application software 1004.
The analog circuitry 1006 and the digital circuitry 1008 include the signal processing, signal conversion, and logic that convert an input signal provided by the I/O element 1016 to an information signal that is to be transmitted. Similarly, the analog circuitry 1006 and the digital circuitry 1008 include the signal processing elements used to generate an information signal that contains recovered information from a received signal. The digital circuitry 1008 can include, for example, a digital signal processor (DSP), a field programmable gate array (FPGA), or any other processing device. Because the baseband subsystem 1010 includes both analog and digital elements, it can be referred to as a mixed signal device (MSD).
In block 1102, a wireless device 1000 is located in a particular area. In block 1104, the metal sensor 1022 in the wireless device 1000 determines whether the wireless device 1000 is located in the vicinity of metal or metallic object.
If in block 1104 the metal sensor 1022 in the wireless device 1000 determines that the wireless device 1000 is not located in the vicinity of metal or metallic object, then in block 1106, the controller 1025 causes the switch 1055 to select the first antenna 1060 and operates in an omni-directional mode.
If in block 1104 the metal sensor 1022 in the wireless device 1000 determines that the wireless device 1000 is located in the vicinity of metal or metallic object, then in block 1108, the controller 1025 causes the switch 1055 to select the second antenna 1065 and operates in a directional mode as a result of the wireless device 1000 being located in the presence of metal.
Although selected aspects have been illustrated and described in detail, it will be understood that various substitutions and alterations may be made therein without departing from the spirit and scope of the present invention, as defined by the following claims.
This application claims priority to, and the benefit of the filing date of, U.S. Provisional Application No. 61/880,397, filed on Sep. 30, 2013, entitled “Multiple Antenna System For A Wireless Device” which is hereby incorporated into this document by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61880397 | Sep 2013 | US |
