Patent Application
20090143040
The present invention relates to the field of communications devices, and, more particularly, to mobile wireless communications devices and antennas therefor and related methods.
Cellular communications systems continue to grow in popularity and have become an integral part of both personal and business communications. Cellular telephones allow users to place and receive voice calls most anywhere they travel. Moreover, as cellular telephone technology has increased, so too has the functionality of cellular devices and the different types of devices available to users. For example, many cellular devices now incorporate personal digital assistant (PDA) features such as calendars, address books, task lists, etc. Moreover, such multi-function devices may also allow users to wirelessly send and receive electronic mail (email) messages and access the Internet via a cellular network and/or a wireless local area network (WLAN), for example.
Even so, as the functionality of cellular communications devices continues to increase, so too does the demand for smaller devices which are easier and more convenient for users to carry. One challenge this poses for cellular device manufacturers is designing antennas that provide desired operating characteristics within the relatively limited amount of space available for the antenna.
One approach for reducing phone size is to use flip phones having top and bottom housings connected with a hinge. The housings may be closed when the phone is not in use so that it is more compact and easier for a user to carry. One exemplary antenna system for a flip style cellular phone is described in U.S. Pat. No. 6,765,536. In particular, the antenna system includes an external antenna element carried on the top of the lower housing, and a parasitic element carried by the top housing so that when the phone is flipped open the parasitic element is in close proximity to the antenna element. A tuning circuit carried by the lower housing is electrically coupled to the parasitic element. The tuning circuit is variable to adjust the parasitic load on the antenna element to provide variable operating frequencies and bandwidths for the phone.
External cell phone antennas are advantageous in that they are spaced apart from the user's head, which makes it easier for phone manufacturers to comply with applicable specific absorption rate (SAR) requirements, for example. This is because the farther the radiating element of the cell phone antenna system is from the user, the less intense the radiation exposure to the user. Yet, many users prefer internal antennas over external antennas, as external antennas are prone to catch on objects and become damaged, for example. Yet, with the ever increasing trend towards smaller cell phone sizes, for a relatively small phone having an internal antenna, this may place the antenna in relatively close proximity to the user's ear, which may make complying with applicable SAR and/or hearing aid compatibility (HAC) requirements potentially difficult for manufacturers.
One exemplary mobile phone configuration that attempts to address radiation concerns from an internal antenna is set forth in PCT Publication No. WO/2004/021511 A2. The device includes a casing including a first in-built driven antenna element extending a length along a longest side of the casing. Either the portable communication device or the case includes at least one passive beam directive element distanced from and generally extending along at least most of the same length as the first in-built driven antenna element. Because of this, electromagnetic radiation generated by the first in-built driven antenna element is enhanced in a direction away from a side of the casing intended to be facing a user.
Despite the existence of such configurations, further improvements may be desirable in certain applications, particularly where the form factor of the device housing does not provide adequate space for such arrangements.
The present description is made with reference to the accompanying drawings, in which preferred embodiments are shown. However, many different embodiments may be used, and thus the description 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. Like numbers refer t o like elements throughout.
Generally speaking, a mobile wireless communications device is disclosed herein which may include a portable housing, a circuit board carried by the portable housing and comprising a ground plane, and wireless communications circuitry carried by the circuit board. Furthermore, the device may also include an antenna assembly carried by the housing. The antenna assembly may include a flexible substrate, an electrically conductive antenna element on the flexible substrate and connected to the wireless communications circuitry and the ground plane, and at least one pair of floating, electrically conductive director elements on opposite sides of the flexible substrate for directing a beam pattern of the antenna element.
More particularly, the floating, electrically conductive director elements may be generally parallel to one another. The flexible substrate may include a wrap-around portion adjacent a bottom of the housing. Moreover, portions of the electrically conductive antenna element may be on the wrap-around portion.
In addition, the electrically conductive antenna element may include at least one loop portion. More specifically, the electrically conductive antenna element may have a generally rectangular shape with at least one slotted opening therein defining the at least one loop portion. Also, the electrically conductive antenna element may further includes a first feed point for the wireless communications circuitry and a second feed point for the ground plane.
The floating, electrically conductive director elements may have a generally elongate shape extending vertically outwardly from the electrically conductive antenna element. Further, the portable housing may have a top and bottom, and the floating, electrically conductive director elements may extend from the bottom of the portable housing toward the top. At least one of the floating, electrically conductive director elements may have a cut-out therein.
A related antenna assembly, such as the one described briefly above, and a related method for making a mobile wireless communications device are also provided. The method may include positioning wireless communications circuitry on a circuit board comprising a ground plane, and mounting an antenna assembly on a portable housing, such as the one described briefly above. The method may further include connecting the circuit board to the portable housing so that the electrically conductive antenna element is connected to the wireless communication circuitry and the ground plane.
Referring initially to
The device 20 illustratively includes a portable housing 24 and an audio output transducer 28 (e.g., a speaker) carried by the housing and accessible to the electronic hearing aid 22 of the user 21 adjacent the top of the housing as shown. An audio input transducer 32 (e.g., microphone) is also carried by the housing 24 and accessible to a mouth 31 of the user 21 adjacent the bottom of the housing. Although described herein with reference to a cellular device, it should be noted that the present disclosure may be applicable to other wireless communications devices such as wireless LAN devices, etc.
The cellular telephone 20 further illustratively includes a printed circuit board (PCB) 37 carried by the housing 24 and wireless communications circuitry 38 (e.g., cellular transceiver, etc.) carried by the PCB. In the illustrated embodiment, the wireless communications circuitry 38 is carried on the back on the PCB 37, but in other embodiments it may be carried on the front side, for example. A ground plane 39 is illustratively carried on a front surface of the PCB 37, although the ground plane may be located elsewhere in other embodiments, as will be appreciated by those skilled in the art. The device 20 may further include other components carried by the housing 24 and/or PCB 37 such as a display, battery, keypad, processing circuitry, etc., as will be discussed further below.
The portable housing 24 has a top 40t, bottom 40b (
In the illustrated example, the antenna assembly 35 is secured to the housing 24 underneath where a battery cover (not shown) is attached to the back of the housing. That is, when the battery cover is connected to the housing 24, it covers the antenna assembly 35 so it is not visible to a user. However, it should be noted that other placements and/or approaches for securing the antenna assembly 35 to the housing may also be used. The structure of the antenna element 36 is discussed further below.
The antenna element 36 may take the form of one or more single or multi-feed point antenna elements (monopole, inverted F, etc.), for example, as will be appreciated by those skilled in the art. In the illustrated embodiment, the antenna element 36 is a multi-band inverted F antenna which advantageously covers GSM 850/900/1800/1900 bands, although other bands (e.g., UMTS 2100 MHz) may also be used by appropriate adjustment of electrical length, etc., as will be appreciated by those skilled in the art. The antenna element 36 overall has a generally rectangular shape with one or more slotted openings 48 therein defining a loop portion 47. In the illustrated embodiment there is a single loop portion 47, but in other embodiments there may be multiple slotted openings defining multiple loops, as seen in related co-pending application Ser. No. 11/863,324, which is assigned to the present Assignee and is hereby incorporated herein in its entirety by reference.
The antenna element 36 further illustratively includes a first feed point 51 that is electrically connected to the wireless communications circuitry 38, and a second feed point 52 that is electrically connected to the ground plane 39. Both of the first and second feed points 51, 52 are coupled or connected to the loop portion 47, as seen in
The folded, loop-back configuration of the loop 47 advantageously provides a relatively compact antenna design compared with an equivalent traditional monopole or inverted F antenna. This may advantageously provide a smaller footprint, which results in a greater surface integration area savings. By way of example, in the illustrated embodiment the antenna element 36 has a generally rectangular footprint of about 1.5 cm tall by 4 cm wide, although other sizes and dimensions may be used in different embodiments. The lengths and shapes of the loop portion 47 may advantageously be chosen to provide an effective electrical length of λ/4 of the respective operating frequencies of the antenna element 36, as will be appreciated by those skilled in the art.
In the present example, the antenna element 36 is positioned adjacent the bottom 40b of the PCB 37 and therefore the bottom of the housing 24 (i.e., adjacent where the input transducer 32 is). This advantageously helps reduce coupling to the electronic hearing aid 22 of the user 21 with respect to traditional top-mounted, internal cellular phone antennas. This is because the electronic hearing aid 22 of the user 21 is advantageously further separated from the antenna element 36 when the cellular telephone 20 is held adjacent the user's ear 23 than would otherwise be the case with a typical top-mounted, internal cellular telephone antenna, for example. Moreover, this antenna placement also helps space the antenna element 36 farther apart from the user's brain, which in turn helps to reduce the SAR of the device 20 again with respect to a traditional top-mounted, internal cellular phone antenna. However, it should be noted that a top-mounted or other antenna placement may be used in some embodiments.
Nonetheless, if the portable housing 24 has a relatively small form factor or footprint for user convenience, this means that the antenna 35 may still be positioned relatively close to the user's ear 23, thus potentially elevating the SAR or coupling to the hearing aid 22 to unacceptable levels. Moreover, close proximity of the antenna element 36 to a user's head may also cause interference with a typical cellular antenna radiation pattern, for example.
As such, the antenna assembly 35 further advantageously includes one or more pairs of floating, electrically conductive director elements 30a, 30b on the flexible substrate 45 for directing a beam pattern of the antenna element 36. More particularly, in the illustrated configuration the director elements 30a, 30b direct the beam pattern of the antenna element 36 away from the user, as seen in
In the illustrated embodiment the director elements 30a, 30b have a generally rectangular shape with a lower end laterally adjacent the antenna element 36. The director element 30a has a cut-out 55 therein (
More particularly, the director elements 30a, 30b illustratively have elongate shapes extending vertically outwardly from the antenna element 36, as seen in
Generally speaking, it is desirable to match the director elements 30a, 30b to the operating frequencies of the antenna element 36. By way of example, one of the director elements 30a, 30b may be matched to the lower frequency bands (e.g., GSM 850/900), while the other is matched to the upper frequency bands (e.g., GSM 1800/1900), although other configurations are possible in different embodiments. In the illustrated example, the director elements 30a, 30b have overall lengths of about 4-6 cm, and widths varying from about 1 to 4 mm, although other dimensions are also possible in other dimensions.
In the illustrated example, the director elements 30a, 30b are not on the wrap-around portion 53 of the flexible substrate 45, although some portions of at least one of the director elements may be on the wrap-around portion in some embodiments. The flexible substrate 45 advantageously facilitates the placement of the antenna element 36 (or multiple elements in other embodiments) and director elements 30a, 30b during manufacturing, which may avoid the potential difficulty of printing conductive traces on portions of the housing 24, for example. Moreover, the flexible substrate 45 may be relatively easily patterned to fit numerous styles and/or sizes of housings 24. Furthermore, the flexible substrate 45 allows the antenna element 36 to be placed in locations other than on the PCB 37, so that the PCB surface area can be used for other elements. The flexible substrate 45 also provides for the relatively easy wrapping around the bottom 40b, etc., of the portable housing 24. This may therefore take advantage of potentially otherwise unused housing 24 surface area so that less of the back-side of the housing, which may need to be used for battery slots, camera lenses, etc., is required. A camera lens 56 and flash 57 are incorporated in the exemplary device 20 (
In the embodiment illustrated in
A related method for making a mobile wireless communications device 20 is now briefly described with reference to
Exemplary components that may be used in the device 20 will now be described in the following example with reference to a wireless communications device 1000 shown in
The housing 1200 may be elongated vertically, or may take on other sizes and shapes (including clamshell housing structures). The keypad may include a mode selection key, or other hardware or software for switching between text entry and telephony entry.
In addition to the processing device 1800, other parts of the mobile device 1000 are shown schematically in
Operating system software executed by the processing device 1800 is preferably stored in a persistent store, such as the flash memory 1160, but may be stored in other types of memory devices, such as a read only memory (ROM) or similar storage element. In addition, system software, specific device applications, or parts thereof, may be temporarily loaded into a volatile store, such as the random access memory (RAM) 1180. Communications signals received by the mobile device may also be stored in the RAM 1180.
The processing device 1800, in addition to its operating system functions, enables execution of software applications 1300A-1300N on the device 1000. A predetermined set of applications that control basic device operations, such as data and voice communications 1300A and 1300B, may be installed on the device 1000 during manufacture. In addition, a personal information manager (PIM) application may be installed during manufacture. The PIM is preferably capable of organizing and managing data items, such as e-mail, calendar events, voice mails, appointments, and task items. The PIM application is also preferably capable of sending and receiving data items via a wireless network 1401. Preferably, the PIM data items are seamlessly integrated, synchronized and updated via the wireless network 1401 with the device user's corresponding data items stored or associated with a host computer system.
Communication functions, including data and voice communications, are performed through the communications subsystem 1001, and possibly through the short-range communications subsystem. The communications subsystem 1001 includes a receiver 1500, a transmitter 1520, and one or more antennas 1540 and 1560. In addition, the communications subsystem 1001 also includes a processing module, such as a digital signal processor (DSP) 1580, and local oscillators (LOs) 1601. The specific design and implementation of the communications subsystem 1001 is dependent upon the communications network in which the mobile device 1000 is intended to operate. For example, a mobile device 1000 may include a communications subsystem 1001 designed to operate with the Mobitex™, Data TAC™ or General Packet Radio Service (GPRS) mobile data communications networks, and also designed to operate with any of a variety of voice communications networks, such as AMPS, TDMA, CDMA, WCDMA, PCS, GSM, EDGE, etc. Other types of data and voice networks, both separate and integrated, may also be utilized with the mobile device 1000. The mobile device 1000 may also be compliant with other communications standards such as 3GSM, 3GPP, UMTS, etc.
Network access requirements vary depending upon the type of communication system. For example, in the Mobitex and DataTAC networks, mobile devices are registered on the network using a unique personal identification number or PIN associated with each device. In GPRS networks, however, network access is associated with a subscriber or user of a device. A GPRS device therefore requires a subscriber identity module, commonly referred to as a SIM card, in order to operate on a GPRS network.
When required network registration or activation procedures have been completed, the mobile device 1000 may send and receive communications signals over the communication network 1401. Signals received from the communications network 1401 by the antenna 1540 are routed to the receiver 1500, which provides for signal amplification, frequency down conversion, filtering, channel selection, etc., and may also provide analog to digital conversion. Analog-to-digital conversion of the received signal allows the DSP 1580 to perform more complex communications functions, such as demodulation and decoding. In a similar manner, signals to be transmitted to the network 1401 are processed (e.g. modulated and encoded) by the DSP 1580 and are then provided to the transmitter 1520 for digital to analog conversion, frequency up conversion, filtering, amplification and transmission to the communication network 1401 (or networks) via the antenna 1560.
In addition to processing communications signals, the DSP 1580 provides for control of the receiver 1500 and the transmitter 1520. For example, gains applied to communications signals in the receiver 1500 and transmitter 1520 may be adaptively controlled through automatic gain control algorithms implemented in the DSP 1580.
In a data communications mode, a received signal, such as a text message or web page download, is processed by the communications subsystem 1001 and is input to the processing device 1800. The received signal is then further processed by the processing device 1800 for an output to the display 1600, or alternatively to some other auxiliary I/O device 1060. A device user may also compose data items, such as e-mail messages, using the keypad 1400 and/or some other auxiliary I/O device 1060, such as a touchpad, a rocker switch, a thumb-wheel, or some other type of input device. The composed data items may then be transmitted over the communications network 1401 via the communications subsystem 1001.
In a voice communications mode, overall operation of the device is substantially similar to the data communications mode, except that received signals are output to a speaker 1100, and signals for transmission are generated by a microphone 1120. Alternative voice or audio I/O subsystems, such as a voice message recording subsystem, may also be implemented on the device 1000. In addition, the display 1600 may also be utilized in voice communications mode, for example to display the identity of a calling party, the duration of a voice call, or other voice call related information.
The short-range communications subsystem enables communication between the mobile device 1000 and other proximate systems or devices, which need not necessarily be similar devices. For example, the short-range communications subsystem may include an infrared device and associated circuits and components, or a Bluetooth™ communications module to provide for communication with similarly-enabled systems and devices.
Many modifications and other embodiments will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that various modifications and embodiments are intended to be included within the scope of the appended claims.
