Note: Descriptions are shown in the official language in which they were submitted.
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MOBILE WIRELESS COMMUNICATIONS DEVICE INCLUDING PARALLEL NFC
LOOP ANTENNAS AND ASSOCIATED METHODS
Technical Field
[0001] This application relates to the field of
communications, and more particularly, to wireless
communications systems and related methods.
Background
[0002] Mobile communication systems continue to grow in
popularity and have become an integral part of both personal
and business communications. Various mobile devices now
incorporate Personal Digital Assistant (PDA) features such
as calendars, address books, task lists, calculators, memo
and writing programs, media players, games, etc. These
multi-function devices usually allow electronic mail (email)
messages to be sent and received wirelessly, as well as
access the internet via a cellular network and/or a wireless
local area network (WLAN), for example.
[0003] Some mobile devices incorporate contactless card
technology and/or near field communication (NFC) chips. NFC
technology is commonly used for contactless short-range
communications based on radio frequency identification
(RFID) standards, using magnetic field induction to enable
communication between electronic devices, including mobile
wireless communications devices. This short-range high
frequency wireless communications technology exchanges data
between devices over a short distance, such as only a few
centimeters.
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Brief Description of the Drawings
[0004] FIG. 1 is a schematic block diagram of a wireless
mobile communications system in accordance with an example
embodiment.
[0005] FIG. 2 is a schematic diagram of the antenna
assembly illustrated in FIG. 1.
[0006] FIG. 3 is a schematic block diagram illustrating
example mobile wireless communications device components
that may be used with the system and devices of FIGS. 1 and
2.
Detailed Description
[0007] The present description is made with reference to
the accompanying drawings, in which various 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 to like elements throughout.
[0008] In accordance with one exemplary aspect, a mobile
wireless communications device comprises a portable housing,
an NFC transceiver carried by the portable housing, and an
antenna assembly carried by the portable housing and coupled
to the NFC transceiver. The antenna assembly may comprise a
plurality of nested loop antennas coupled in parallel, and
progressively increasing in size from an innermost loop
antenna to an outermost loop antenna.
[0009] As will be explained in greater detail below, the
antenna assembly maintains payment certification
requirements (as defined by EMVCo) for large tags, while
also increasing performance for small tags. Small tags may
be used for Bluetooth pairing and interfacing with docking
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stations, for example. The plurality of nested loop antennas
may be non-concentric. This further helps to increase
magnetic flux coverage for the small tags.
[0010] The plurality of nested loop antennas may comprise
three loop antennas. Each loop antenna may have a
rectangular shape with opposing ends and opposing sides
coupled thereto.
[0011] The mobile wireless communications device may
further comprise a pair of antenna feed points, and wherein
the plurality of nested loop antennas each have respective
ends adjacent one another, and adjacent the pair of antenna
feed points and coupled thereto. The antenna assembly may
further comprise a dielectric substrate, and wherein each
loop antenna may comprise at least one loop conductor
carried by the dielectric substrate.
[0012] The portable housing may comprise a removable
battery cover, and wherein the antenna assembly may be
carried by the removable battery cover. The innermost loop
antenna may be about 15 mm by 15 mm, and the outermost loop
antenna may be about 85 mm by 54 mm.
[0013] The mobile wireless communications device may
further comprise a cellular transceiver carried by the
portable housing, and a cellular antenna coupled to the
cellular transceiver.
[0014] A method aspect is directed to making a mobile
wireless communications as described above. The method may
comprise positioning an NFC transceiver within a portable
housing, and coupling an antenna assembly to the NFC
transceiver within the portable housing. The antenna
assembly may comprise a plurality of nested loop antennas
connected in parallel, and progressively increasing in size
from an innermost loop antenna to an outermost loop antenna.
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[0015] Referring initially to FIG. 1, the mobile wireless
communications device 10 includes a portable housing 12 and
an NFC transceiver 20 carried by the portable housing, and
an antenna assembly 30 coupled to the NFC transceiver. The
antenna assembly 30 includes a plurality of loop antennas
connected in parallel, as will be discussed in greater
detail below. The NFC transceiver 20 may communicate with an
NFC terminal 40, and may operate in either a device reader
mode and a device card emulation mode.
[0016] The mobile wireless communications device 10 also
includes wireless transceiver circuitry 50 carried by the
portable housing 12, and an antenna 52 coupled to the
wireless transceiver circuitry 50. The wireless transceiver
circuitry 50 may be cellular transceiver circuitry or other
types of wireless communications circuitry, and may
communicate any combination of voice and data, such as
email, via a wireless network 14.
[0017] Example mobile wireless communications devices 10
include portable or personal media players, such as music or
MP3 players, and video players. Mobile wireless
communications devices 10 may also include portable gaming
devices, portable or mobile telephones, smartphones, tablet
computers, and digital cameras, for example.
(0018] The mobile wireless communications device 10
includes a display 54 carried by a front exterior surface of
the portable housing 12. The display 54 may be a liquid
crystal display (LCD) and may be configured to display
information relating to a data or voice communications.
(0019] A processor 56 is carried the portable housing 12
and is coupled to the wireless transceiver circuitry 50, the
NFC transceiver 20 and the display 54. The processor 56 may
be implemented using hardware and software components for
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causing the mobile wireless communications device 10 to
perform the various functions or operations described
herein.
[0020] The mobile wireless communications device 10 also
includes a power source 58. For example, the power source 58
may be a rechargeable battery. Nonetheless, other types of
power sources may be used.
[0021] The mobile wireless communications device 10 is
particularly advantageous with respect to NFC
communications, as will now be discussed in greater detail.
The antenna assembly 30 maintains payment certification
requirements (as defined by EMVCo) for large tags, while
also increasing performance for small tags.
[0022] By way of background, NFC is a short-range
wireless communications technology in which NFC-enabled
devices are "swiped," "bumped" or otherwise moved in close
proximity to communicate. NFC enables exchange of data
between two or more wireless devices, generally by inductive
coupling. Inductive coupling may be used for completing
payment card transactions, for interfacing with smart
posters, for Bluetooth pairing and interfacing with docking
stations, for example. Payment cards include credit cards,
gift cards and bank cards, for example.
[0023] Inductive coupling refers to the generation of
voltage/current in one loop or coil due to (and proportional
to) a change in voltage/current (and hence the corresponding
magnetic field) in another loop or coil. The two loops are
termed as being "inductively coupled" to each other, and
which may thus be viewed as antennas. Currently, NFC
communications is standardized and designed to operate
within the globally available and unlicensed radio frequency
ISM band of 13.56 MHz.
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[0024] The antenna assembly 30 includes a plurality of
nested loop antennas 32, 34, 36 connected in parallel, as
best illustrated in FIG. 2. Although three loop antennas 32,
34, 36 are connected in parallel, the actual number may be
more or less depending on the intended applications or the
amount of space available within the mobile wireless
communications device 10.
[0025] The selected number of loop antennas to be
connected in parallel still needs to support a quality (Q)
factor of less than 35, as readily appreciated by those
skilled in the art. The Q factor is determined by dividing
the inductive reactance (ohms) by the resistive losses in
the loops (ohms) at the operating frequency.
[0026] The loop antennas 32, 34, 36 that are connected in
parallel progressively increase in size from an innermost
loop antenna 32 to an outermost loop antenna 36. The loop
antennas 32, 34, 36 are connected to feed points 60, 62 that
are coupled to the NFC transceiver 20. The loop antennas 32,
34, 36 each have respective ends adjacent one another, and
adjacent the pair of antenna feed points 60, 62.
[0027] In addition, the loop antennas 32, 34, 36 are non-
concentric, and have a rectangular shape with opposing ends
and opposing sides coupled thereto. The antenna assembly 30
may include a dielectric substrate 66, with each loop
antenna 32, 34, 36 comprising at least one loop conductor
carried by the dielectric substrate.
[0028] As discussed above, the mobile wireless
communications device 10 includes a power source 58 that may
be configured as a rechargeable battery carried by a back
exterior surface of the portable housing 12. The
rechargeable battery 58 is removable from the portable
housing 12. For this particular configuration of a mobile
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wireless communications device 10, the portable housing 12
comprises a removable battery cover 15, and wherein the
antenna assembly 30 is carried by the removable battery
cover, as illustrated in FIG. 2.
[0029] Performance of the antenna assembly 30 will now be
discussed in reference to TABLE 1. Antenna performance will
be compared against a single antenna. Performance of the
single antenna and the antenna assembly 30 are directed
towards 4 different tag sizes that conform to industry
standards.
[0030] The smallest tag size is 15x15 mm, the middle tag
sizes are circular shaped and have a diameter of 30
TABLE 1
mm and 38 mm, respectively. The largest tag size is 85x54
mm.
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[0031] The smallest tag size may be used for Bluetooth
pairing and interfacing with docking stations, for example.
The circular shaped tags may be used to receive web site
information, for example, from smart posters.
[0032] The largest tag size meets EMVCo contactless
specifications for payment systems. EMVCo, owned by American
- Ex
DEVICEREADERMODEPERFORMANCE pr
es
Tag Size Single Loop Antenna Triple Loop Antenna
s ,
(Max 'Z' Distance) (Max 'Z' Distance JC
15x15 mm 15 mm 21 mm B,
Ma
30 mm dia. 24.5 mm 28.5 mm
St
38 mm dia. 27 mm 30 mm er
85x54 mm 35 mm 36 mm Ca
rd
DEVICE CARD EMULATION MODE PERFOMANCE an
Modulation Type Single Loop Antenna Triple Loop Antenna
Vi
(Max 'Z' Distance) (Max 'Z' Distance) s a
A 53.5 mm 55 mm
en
51 mm 52.5 mm
su
re
s global interoperability of chip-based payment cards with
acceptance devices, including point of sale terminals and
ATMs.
[0033] Operation of the NEC transceiver 20 in a device
reader mode will be discussed first. The max "z" distance
for each antenna configuration corresponds to a height or
separation distance from the NEC terminal 40. For the
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smallest tag size, the single antenna has a separation
distance of 15 mm, and the antenna assembly 30 has a
separation distance of 21 mm. For the circular shaped tag
having the 30 mm diameter, the single antenna has a
separation distance of 24.5 mm, and the antenna assembly 30
has a separation distance of 28.5 mm. For the circular
shaped tag having the 38 mm diameter, the single antenna has
a separation distance of 27 mm, and the antenna assembly 30
has a separation distance of 30 mm. For the largest tag
size, the single antenna has a separation distance of 35 mm,
and the antenna assembly 30 has a separation distance of 36
mm.
[0034] The increased separation distances provided by the
antenna assembly 30 flattens out as antenna sizes increase.
However, the antenna assembly 30 advantageously increases
small tag reading distances. The loop antennas 32, 34, 36 in
the antenna assembly 30 are coupled to antenna feed points
60 and 62, which provide a voltage generated by the NFC
transceiver 20. The voltage provided by the feed points 60,
62 generate current that travels around each loop antenna
32, 34, 36 to generate magnetic fields. The magnetic fields
are at a constant level and are evenly distributed in the
loop areas, i.e., x and y.
[0035] The loop antennas 32, 34, 36 pick up magnetic
fields within their loop areas. Since the small loop antenna
32 is about 1/5 the size of the large loop antenna 36, it
only picks up about 1/5 of the magnetic field as compared to
that of the larger loop antenna 36. Similar analysis applies
to the middle loop antenna 34.
[0036] Since the loop antennas 32, 34, 36 are nested and
non-concentric, and the smaller size loop antennas 32, 34
are positioned within the larger size loop antenna 36 toward
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the top of the mobile wireless communications device 10, the
field patterns are directed toward the top. The inductive
coupling from the larger loop antenna 36 helps to increase
the inductive coupling of the middle loop antenna 34, and
the inductive coupling from the middle and larger loop
antennas 36, 34 help to increase the inductive coupling of
the small loop antenna 32.
[0037] Operation of the NFC transceiver 20 in a device
card emulation mode will be now discussed. The max "z"
distance for each antenna configuration corresponds to a
height or separation distance from the NFC terminal 40.
Based on ISO standards, there is a modulation type A and a
modulation type B. For the single antenna, the separation
distances correspond to 53.5 mm and 51 mm, respectively. For
the antenna assembly 30, the separation distances correspond
to 55 mm and 52.5 mm, respectively. There is a slight
increase in performance with the antenna assembly 30.
[0038] As noted above, antenna assembly 30 needs to
support a quality (Q) factor of less than 35. Another
definition of the Q factor corresponds to bandwidth. The
wider the bandwidth the lower the Q factor. With a single
antenna configuration, resistances are typically added to
drop the Q factor to meet the data rate requirement. In lieu
of adding resistances, additional loop antennas can be
connected in parallel to maintain the same Q factor. In
other words, the headroom associated with the single antenna
can be applied to parallel antennas while increasing NFC
performance for smaller size tags.
[0039] Example components of a mobile wireless
communications device 1000 that may be used in accordance
with the above-described embodiments are further described
below with reference to FIG. 3. The device 1000
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illustratively includes a housing 1200, a keyboard or keypad
1400 and an output device 1600. The output device shown is a
display 1600, which may comprise a full graphic LCD. Other
types of output devices may alternatively be utilized. A
processing device 1800 is contained within the housing 1200
and is coupled between the keypad 1400 and the display 1600.
The processing device 1800 controls the operation of the
display 1600, as well as the overall operation of the mobile
device 1000, in response to actuation of keys on the keypad
1400.
[0040] 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.
[0041] In addition to the processing device 1800, other
parts of the mobile device 1000 are shown schematically in
FIG. 4. These include a communications subsystem 1001; a
short-range communications subsystem 1020; the keypad 1400
and the display 1600, along with other input/output devices
1060, 1080, 1100 and 1120; as well as memory devices 1160,
1180 and various other device subsystems 1201. The mobile
device 1000 may comprise a two-way RE communications device
having data and, optionally, voice communications
capabilities. In addition, the mobile device 1000 may have
the capability to communicate with other computer systems
via the Internet.
[0042] Operating system software executed by the
processing device 1800 is 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,
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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.
[0043] 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 13003, may
be installed on the device 1000 during manufacture. In
addition, a personal information manager (PIM) application
may be installed during manufacture. The PIM may be capable
of organizing and managing data items, such as e-mail,
calendar events, voice mails, appointments, and task items.
The PIM application may also be capable of sending and
receiving data items via a wireless network 1401. The PIM
data items may be seamlessly integrated, synchronized and
updated via the wireless network 1401 with corresponding
data items stored or associated with a host computer system.
[0044] 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
(L0s) 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
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include a communications subsystem 1001 designed to operate
with the MobitexTM, Data TACm 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, 4G, etc.
[0045] 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 typically involves
use of a subscriber identity module, commonly referred to as
a SIM card, in order to operate on a GPRS network.
[0046] 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
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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.
[0047] 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.
[0048] 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 may also be used to 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.
[0049] 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
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mode, for example to display the identity of a calling
party, the duration of a voice call, or other voice call
related information.
[0050] 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, a Bluetoothm communications module
to provide for communication with similarly-enabled systems
and devices, or a near field communications (NFC) sensor for
communicating with an NFC device or NFC tag vian NFC
communications.
[0051] 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.
