Technical Field
[0001] The present invention relates to the field of communications, and, more particularly,
to wireless communications and related methods.
Background
[0002] Cellular communication 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 phone calls almost anywhere they travel. Moreover, as cellular
telephone technology is improved, so too has the functionality of cellular devices.
For example, many cellular devices now incorporate Personal Digital Assistant (PDA)
features such as calendars, address books, task lists, calculators, memo and writing
programs, etc. These multifunction devices usually 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.
[0003] As the functionality of cellular devices continues to increase, so too does demand
for smaller devices that are easier and more convenient for users to carry. Nevertheless,
the move towards multi-functional devices makes miniaturization more difficult as
the requisite number of installed components increases. Indeed, the typical cellular
device may include several antennas, for example, a cellular antenna, a global positioning
system antenna, and a WiFi IEEE 802.11g antenna. These antennas may comprise external
antennas and internal antennas.
[0004] Generally speaking, internal antennas allow cellular devices to have a smaller footprint.
Moreover, they are also preferred over external antennas for mechanical and ergonomic
reasons. Internal antennas are also protected by the cellular device's housing and
therefore tend to be more durable than external antennas. External antennas may be
cumbersome and may make the cellular device difficult to use, particularly in limited-space
environments. Yet, one potential drawback of typical internal antennas is that they
are in relatively close proximity to the user's head when the cellular device is in
use, thereby increasing the specific absorption rate (SAR). Yet more, hearing aid
compatibility (HAC) may also be affected negatively. Also, other components within
the cellular device may cause interference with or may be interfered by the internal
antenna.
Brief Description of the Drawings
[0005] FIG. 1 is a schematic diagram of an example embodiment of the mobile wireless communications
device.
[0006] FIG. 2 is a top plan view of an example embodiment of a multiple-band antenna from
the mobile wireless communications device of FIG. 1.
[0007] FIG. 3 is a side elevation view of the multiple-band antenna of FIG. 2.
[0008] FIG. 4 is a top plan view of another example embodiment of a multiple-band antenna
from the mobile wireless communications device of FIG. 1.
[0009] FIG. 5 is a side elevation view of the multiple-band antenna of FIG. 4.
[0010] FIG. 6 is a top plan view of yet another example embodiment of a multiple-band antenna
from the mobile wireless communications device of FIG. 1 with the dielectric substrate
removed.
[0011] FIG. 7 is a side elevation view of the multiple-band antenna of FIG. 6.
[0012] FIG. 8 is a current distribution diagram of an example embodiment of a secondary
radiator in an antenna that excites mode 3.
[0013] FIG. 9A is a current distribution diagram of an example embodiment of a primary radiator
in the mobile wireless communications device in a first mode.
[0014] FIGS. 9B-9D are far field patterns of an example embodiment of a primary radiator
in the mobile wireless communications device in a first mode.
[0015] FIG. 10A is a current distribution diagram of an example embodiment of a primary
radiator in the mobile wireless communications device in a second mode.
[0016] FIGS. 10B-10D are far field patterns of an example embodiment of a primary radiator
in the mobile wireless communications device in a second mode.
[0017] FIG. 11A is a current distribution diagram of an example embodiment of a primary
radiator in the mobile wireless communications device in a third mode.
[0018] FIGS. 11B-11D are far field patterns of an example embodiment of a secondary radiator
in the mobile wireless communications device in a third mode.
[0019] FIG. 12 is a schematic block diagram illustrating example components of a mobile
wireless communications device that may be used with the mobile wireless communications
device of FIG. 1.
Detailed Description of the Preferred Embodiments
[0020] The present description is made with reference to the accompanying drawings, in which
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, and prime notation is used
to indicate similar elements in alternative embodiments.
[0021] Generally speaking, a mobile wireless communications device may include a housing,
at least one wireless transceiver carried by the housing and having a primary output,
and a secondary output, and a multiple-band antenna carried by the housing and coupled
to the at least one wireless transceiver. The multiple-band antenna may include a
dielectric substrate and a pattern of electrically conductive traces thereon defining
a primary radiator and a secondary radiator spaced apart from the primary radiator.
The primary radiator may include a first elongate member having a primary feed coupled
to the primary output, and a first reference member spaced from the first elongate
member and at least partially laterally surrounding the first elongate member and
coupled to a reference voltage. The secondary radiator may include a second elongate
member having a secondary feed coupled to the secondary output.
[0022] More specifically, the first reference member may comprise a first arm, and a second
arm coupled thereto. The first arm may have an L-shape, and the second arm may comprise
a proximal portion coupled to the first arm and having an L-shape, and a distal portion
extending away from the proximal portion.
[0023] Additionally, the first arm may extend along a bottom of the housing. The second
elongate member may have a first arm, and a second arm coupled thereto. The secondary
feed may be on the second arm, and the first arm may extend at least partially along
a bottom edge of the housing. The dielectric substrate may have a non-planar shape.
The dielectric substrate may be carried by a bottom of the housing, and the primary
and secondary radiators may be carried by respective opposing first and second sides
of the dielectric substrate. For example, the at least one wireless transceiver may
comprise a Long Term Evolution (LTE) transceiver configured to operate the primary
and secondary outputs in an LTE carrier aggregation mode.
[0024] Another aspect is directed to a method of making a multiple-band antenna for a mobile
wireless communications. The method may comprise forming a multiple-band antenna to
comprise a dielectric substrate and a pattern of electrically conductive traces thereon
defining a primary radiator and a secondary radiator spaced apart from the primary
radiator. The primary radiator may comprise a first elongate member having a primary
feed coupled to the primary output, and a first reference member spaced from the first
elongate member and at least partially laterally surrounding the first elongate member
and coupled to a reference voltage. The secondary radiator may comprise a second elongate
member having a secondary feed coupled to the secondary output.
[0025] Referring initially to FIGS. 1-3, a mobile wireless communications device
20 according to the present disclosure is now described. The mobile wireless communications
device
20 illustratively includes a housing
22, a wireless transceiver
21 carried by the housing and having a primary and secondary outputs
55, 56, and a multiple-band antenna
23 carried by the housing and coupled to the wireless transceiver. For example, the
wireless transceiver
21 may comprise an LTE transceiver configured to operate the primary and secondary outputs
55, 56 in an LTE carrier aggregation mode. In the illustrated embodiment, the multi-band
antenna
23 may operate the primary output
55 at: LTE Band 7, 3, 8, 20, Primary; Wideband Code Division Multiple Access (WCDMA)
Band 1, 2, 5, 8, Primary; Global System for Mobile Communications (GSM) 850, 900,
1800, 1900; and operate the secondary output
56 at LTE Band 7, 3, 8, 20, Multiple Input Multiple Output (MIMO); WCDMA Band 1, 2,
5, 8 Diversity.
[0026] The multiple-band antenna
23 illustratively includes a dielectric substrate
24 and a pattern of electrically conductive traces thereon defining a primary radiator
26 and a secondary radiator
25 spaced apart from the primary radiator. The dielectric substrate
24 illustratively includes a non-planar shape, which illustratively fits the interior
portions of the housing
22. The dielectric substrate
24 may be carried by a bottom of the housing
22, and the primary and secondary radiators
26, 25 may be carried by respective opposing first and second sides of the dielectric substrate.
[0027] The primary radiator
26 illustratively includes a first elongate member
32 having a primary feed
27 coupled to the primary output
55. The primary radiator
26 illustratively includes a first reference member
33 (e.g. ground reference member) spaced from the first elongate member
32 and at least partially laterally surrounding the first elongate member and coupled
to a reference voltage (e.g. ground). The secondary radiator
25 illustratively includes a second elongate member having a secondary feed
31 coupled to the secondary output
56. More specifically, the first reference member
33 illustratively includes a first arm
35, and a second arm
51 coupled thereto.
[0028] In detail, the first elongate member
32 has a substantially rectangular-shape, and extends in parallel with the first arm
35 of the first reference member
33 (bending upward slightly). The first elongate member
32 illustratively includes a top portion defining a recess
57, and a protruding portion
58 partially extending across the recess and including the primary feed
27.
[0029] The first arm
35 of the first reference member
33 is substantially rectangle-shaped, and illustratively includes a proximal portion
59, and a distal portion
60 coupled thereto and having an enlarged width. The distal portion
60 also defines a notch
61 having parallel sides, and a curved end. Additionally, the first arm
35 extends along a bottom of the housing
22.
[0030] The second arm
51 comprises a proximal portion
41 coupled to the first arm
35 and having an L-shape, and a distal portion
42 extending away from the proximal portion and having a rectangular-shape. The distal
portion
42 illustratively includes a reference connection
28 (e.g. ground connection), and defines a recess
62 having a curved end. The proximal and distal portions
41, 42 have straight sides.
[0031] The first reference member
33 illustratively includes a third arm
47 extending almost entirely across the bottom edge of the dielectric substrate
24. The third arm
47 illustratively includes a proximal portion
62, and a distal portion
63 coupled thereto. The proximal portion
62 is rectangle-shaped, and the distal portion
63 is also rectangle-shaped. The distal portion
63 illustratively includes a greater width than that of the proximal portion
62 and has a rectangle-shaped notch
64 adjacent a corner thereof. The distal portion
63 also illustratively defines a square-shaped opening
65.
[0032] The second elongate member illustratively includes a first arm
46, and a second arm
34 coupled thereto. The secondary feed
31 illustratively is on the second arm
34, and the first arm
46 may extend at least partially along a bottom edge of the housing
22. In particular, the first arm
46 illustratively includes rectangle-shaped proximal and distal portions
66, 67, the distal portion defining a rectangle-shaped recess
68 on a side thereof. The second arm
34 illustratively includes a proximal portion
110, a medial portion
111 coupled to the proximal portion, and a distal portion
112 coupled to the medial portion. The proximal portion
110 is rectangle-shaped, and the medial portion
111 is U-shaped. The distal portion
112 comprises an L-shaped portion coupled to the medial portion
111, and a rectangle-shaped portion coupled to the L-shaped portion.
[0033] Another aspect is directed to a method of making a multiple-band antenna
23 for a mobile wireless communications
20. The method may comprise forming a multiple-band antenna
23 to comprise a dielectric substrate
24 and a pattern of electrically conductive traces thereon defining a primary radiator
26 and a secondary radiator
25 spaced apart from the primary radiator. The primary radiator
26 may comprise a first elongate member having a primary feed
27 coupled to the primary output, and a first reference member
33 spaced from the first elongate member and at least partially laterally surrounding
the first elongate member and coupled to a reference voltage. The secondary radiator
25 may comprise a second elongate member having a secondary feed
31 coupled to the secondary output.
[0034] Referring now additionally to FIGS. 4-5, another embodiment of the multiple-band
antenna
23' is now described. In this embodiment of the multiple-band antenna
23', those elements already discussed above with respect to FIGS. 1-3 are given prime
notation and most require no further discussion herein. This embodiment differs from
the previous embodiment in that the first arm
35' illustratively has an L-shape, and uniform width throughout. The first arm
35' also does not include the recess from the embodiments of FIGS. 2-3. The third arm
47' also does not include the notch of the prior embodiment, but does include an L-shaped
turn
120' in a medial portion thereof. The second arm
34' of the secondary radiator
25' illustratively includes a single L-shaped turn
121', rather the multiple turns of the prior embodiments. In the illustrated embodiment,
the multi-band antenna
23' may operate the primary output
55' at: LTE Band 4, 13 Primary; CDMA 1x Voice, EVDO Diversity; WCDMA Band 1, 2, 5, 8
Primary; GSM 850, 900, 1800, 1900; and operate the secondary output
56' at: LTE Band 13 MIMO; CDMA 1x Voice Primary; and CDMA 1x EVDO Diversity.
[0035] Referring now additionally to FIGS. 6-7, another embodiment of the multiple-band
antenna
23" is now described. In this embodiment of the multiple-band antenna
23", those elements already discussed above with respect to FIGS. 1-3 are given double
prime notation and most require no further discussion herein. This embodiment differs
from the previous embodiment in that the third arm
47" includes the rectangle-shaped recess
64" in a medial portion rather than the corner of the embodiment of FIGS. 2-3. Also,
the secondary radiator
25" has a general C-shape including the first and second arms
46", 34". The first arm
46" illustratively includes a pair of rectangle-shaped branches
115', 116'. The second arm
34" illustratively has an L-shape and is rectangle-shaped throughout. In the illustrated
embodiment, the multi-band antenna
23" may operate the primary output
55" at: LTE Band 2, 4, 5, 17 Primary; WCDMA Band 1, 2, 5, 8 Primary; GSM 850, 900, 1800,
1900; and operate the secondary output
56" at: LTE Band 2, 4, 5, 17 MIMO; WCDMA Band 1, 2, 5, 8 Diversity.
[0036] With regards to the operating bands of the embodiments of FIGS. 2-7, the operating
frequencies are shown in Table 1 herein.

Theory of Operation
[0037] The basis of this multiple-band antenna
23 relies on exciting different characteristics modes in the chassis of the mobile wireless
communications device
20. Characteristics modes describe the current distribution and far field radiation that
are unique to a given conducting body at a specific frequency. In theory, a metallic
object could possess infinite number of characteristic mode for a given frequency,
however not all modes are excitable in practice. Mathematically, characteristics modes
on a metal object are precisely described by the following close boundary problem:

where the operator L is defined as

and
A and Φ are the vector and scalar potentials due to a given current distribution respectively.
[0038] Since A and Φ are integrals defined over the closed surface, the problem can be rewritten
in terms of impedances and arrive at the eigenvalues problem as

and

where matrix M is a symmetric matrix that diagonalizes the matrix Z,
v are the eigenvalues, and J are the eigenvectors. A characteristic mode refers to
a given set of eigenvalue and eigenvector.
[0039] By definition, the eigenvectors associated with a particular conducting body are
orthogonal to each other and must satisfy the orthogonality relationships 〈
Jm|
ZJn〉 = 0, for
m ≠
n. In other words, the current distribution and radiation pattern of one mode is un-correlated
to the current distribution and radiation pattern of another mode, even though there
is only one radiating element. By exploiting this orthogonality principle of characteristic
modes, the multiple-band antenna
23 can achieve low correlation at low frequencies despite having only one radiator and
it is this particular property that enables this feature. More specifically, the first
elongate member
32 in N-series excites a dominant mode 1 (
v1,
J1) and the secondary radiator
25 excites a dominant mode 3 (
v3,
J3).
[0040] Referring now to FIGS. 8-11D, diagram
77 shows the current distribution, and diagrams
79, 81, 83 show the far field patterns for the mobile wireless communications device
20 while in mode 1 at 704 MHz. Diagram
85 shows the current distribution, and diagrams
87, 89, 91 show the far field patterns for the mobile wireless communications device
20 while in mode 2 at 704 MHz. Diagrams
93, 70 show the current distribution, and diagrams
95, 97, 99 show the far field patterns for the mobile wireless communications device
20 while in mode 3 at 704 MHz.
[0041] The multiple-band antenna
23 may exploit the natural resonances, known as characteristics modes, of an arbitrary
metallic object to achieve low correlation between multiple antennas in a MIMO system.
Typical MIMO systems may rely on an antenna array where the antenna elements are usually
separated from each other by half of a wavelength. For low frequency LTE bands, such
as Band 17 (704 MHz - 746 MHz) or Band 13 (746 MHz - 777 MHz), the half wavelength
spatial separation may not be achievable in handheld devices, such as a smartphone
where the overall dimension of the device is on the order of a quarter wavelength
of the operating wavelength. Low frequency is particularly interesting because radiation
at low frequencies is predominantly due to the mobile device's chassis and the antenna
element serves as an excitation element. Consequently, the current distributions excited
by each antenna element in a MIMO system share one radiator, i.e. the chassis of the
device. This is in conflict to the multi-antenna requirement of MIMO because multiple
antennas usually mean that there are multiple radiating elements, which may not be
true in a handset. The multiple-band antenna
23 may relax this requirement and enable: high performance MIMO with a single radiating
element; and systematic antenna element placement with minimal correlation and gain
imbalance.
[0042] With regards to Table 2 below, the measured performance of the multi-band antenna
23 in varying operating frequencies is shown. Of particular interest is the LTE MIMO
and Correlation section, which demonstrate the low correlation values achieved with
the multi-band antenna
23.

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.
[0043] 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.
[0044] In addition to the processing device
1800, other parts of the mobile device
1000 are shown schematically in FIG. 12. 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 RF 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.
[0045] 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, 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.
[0046] 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 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.
[0047] Communication functions, including data and voice communications, are performed through
the communications subsystem
1001, and possibly through the short-range communications subsystem
1020. 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
Advanced Mobile Phone System (AMPS), time division multiple access (TDMA), code division
multiple access (CDMA), Wideband code division multiple access (W-CDMA), personal
communications service (PCS), GSM (Global System for Mobile Communications), enhanced
data rates for GSM evolution (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, 3rd Generation
Partnership Project (3GPP), Universal Mobile Telecommunications System (UMTS), 4G,
etc.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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 Bluetooth™ communications module to provide
for communication with similarly-enabled systems and devices, or a NFC sensor for
communicating with a NFC device or NFC tag via NFC communications.
[0054] 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.