U.S. patent application number 17/029904 was filed with the patent office on 2022-02-10 for antenna system including spherical reflector with metamaterial edges.
This patent application is currently assigned to LOON LLC. The applicant listed for this patent is SoftBank Corp.. Invention is credited to Sharath Ananth, Paul Heninwolf, Jean-Laurent Plateau.
Application Number | 20220045432 17/029904 |
Document ID | / |
Family ID | 1000006104977 |
Filed Date | 2022-02-10 |
United States Patent
Application |
20220045432 |
Kind Code |
A1 |
Ananth; Sharath ; et
al. |
February 10, 2022 |
ANTENNA SYSTEM INCLUDING SPHERICAL REFLECTOR WITH METAMATERIAL
EDGES
Abstract
An antenna for wireless communication includes a spherical
reflector and one or more feeds. The spherical reflector includes
an inner portion made of material that reflects radiofrequency (RF)
beams, and an outer portion positioned on an edge of the inner
portion, the outer portion being made of metamaterials that can be
controlled to be reflective of or transparent to RF beams. The one
or more feeds are configured to form one or more RF beams reflected
off the spherical reflector. In some implementations, the antenna
includes one or more processors configured to form one or more RF
beams using the one or more feeds, and control at least a part of
the outer portion of the spherical reflector to reflect an RF beam
of the one or more RF beams or be transparent to the RF beam based
on the one or more RF beam.
Inventors: |
Ananth; Sharath; (Cupertino,
CA) ; Heninwolf; Paul; (San Carlos, CA) ;
Plateau; Jean-Laurent; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SoftBank Corp. |
Tokyo |
|
JP |
|
|
Assignee: |
LOON LLC
Mountain View
CA
|
Family ID: |
1000006104977 |
Appl. No.: |
17/029904 |
Filed: |
September 23, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16986527 |
Aug 6, 2020 |
|
|
|
17029904 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01Q 1/28 20130101; H01Q
15/0086 20130101; H01Q 19/12 20130101 |
International
Class: |
H01Q 15/00 20060101
H01Q015/00; H01Q 19/12 20060101 H01Q019/12; H01Q 1/28 20060101
H01Q001/28 |
Claims
1. An antenna for wireless communication comprising: a spherical
reflector including: an inner portion made of material that
reflects radiofrequency (RF) beams, and an outer portion positioned
on an edge of the inner portion, the outer portion being made of
metamaterials that can be controlled to be reflective of or
transparent to RF beams; and one or more feeds configured to form
one or more RF beams reflected off the spherical reflector.
2. The antenna of claim 1, wherein the spherical reflector is less
than a hemisphere.
3. The antenna of claim 1, wherein the antenna is part of a
high-altitude platform.
4. The antenna of claim 1, wherein the outer portion of the
spherical reflector is controlled using an electrical signal
applied to at least a part of the outer portion.
5. The antenna of claim 1, wherein the outer portion of the
spherical reflector includes a plurality of metamaterials
sections.
6. The antenna of claim 5, wherein each metamaterials section of
the plurality of metamaterials sections is independently
controllable.
7. The antenna of claim 5, further comprising one or more
processors configured to: form one or more RF beams using the one
or more feeds, and control at least a part of the outer portion of
the spherical reflector to reflect an RF beam of the one or more RF
beams or be transparent to the RF beam based on the one or more RF
beam.
8. The antenna of claim 7, wherein the one or more processors are
further configured to determine one or more reflective sections of
the plurality of metamaterials sections or one or more transparent
sections of the plurality of metamaterials sections for each RF
beam of the one or more RF beams.
9. The antenna of claim 7, wherein the at least a part of the outer
portion of the spherical reflector is controlled based on a
location of the antenna and one or more target locations.
10. The antenna of claim 9, wherein the one or more target
locations includes a ground-based terminal and an airborne
terminal.
11. A method for controlling an antenna system having a spherical
reflector that includes a plurality of metamaterials sections, the
method comprising: determining, by one or more processors, one or
more radiofrequency (RF) beams to be formed by the antenna system
based on a location of the antenna system of a terminal and a
target location; determining, by the one or more processors, one or
more reflector sections or one or more transparent sections in the
plurality of metamaterials sections for the one or more RF beams;
applying, by the one or more processors, an electrical signal to
one or more of the plurality of metamaterials sections to cause the
one or more of the metamaterials sections to become reflective of
or transparent to an RF beam according to the one or more reflector
sections and the one or more transparent sections; and causing, by
the one or more processors, the antenna system to transmit the one
or more RF beams.
12. The method of claim 11, wherein the determining of the one or
more reflector sections or the one or more transparent sections is
based on a location of the antenna system and one or more target
locations.
13. The method of claim 12, wherein the one or more target
locations includes a ground-based terminal and an airborne
terminal.
14. The method of claim 11, wherein the electrical signal is a
first electrical signal applied at a first point in time; and the
method further comprises applying, by the one or more processors, a
second electrical signal at a second point in time after the first
point in time to switch the one or more of the metamaterials
sections from reflective to transparent or from transparent to
reflective.
15. The method of claim 11, further comprising: predicting, by the
one or more processors, a disruption to a first RF beam based on a
location of the one or more reflector sections or the one or more
transparent sections corresponding to a second RF beam; and
determining, by the one or more processors, to transmit the second
RF beam at a given point in time when the first RF beam is not to
be transmitted.
16. The method of claim 11, wherein the spherical reflector is less
than a hemisphere.
17. The method of claim 11, wherein the spherical reflector is a
whole sphere.
18. A non-transitory computer readable medium on which instructions
are stored, the instructions, when executed by one or more
processors in a high-altitude platform (HAP) node, cause the one or
more processors to perform a method for controlling an antenna
system, the method comprising: determining one or more
radiofrequency (RF) beams to be formed by the antenna system based
on a location of the HAP and a target location, the antenna system
including a spherical reflector including a plurality of
metamaterials sections; determining one or more reflector sections
or one or more transparent sections in the plurality of
metamaterials sections for the one or more RF beams; applying an
electrical signal to one or more of the plurality of metamaterials
sections to cause the one or more of the metamaterials sections to
become reflective of or transparent to an RF beam according to the
one or more reflector sections and the one or more transparent
sections; and causing, the antenna system to transmit the one or
more RF beams.
19. The medium of claim 18, wherein the electrical signal is a
first electrical signal applied at a first point in time; and the
method further comprises applying a second electrical signal at a
second point in time after the first point in time to switch the
one or more of the plurality of metamaterials sections from
reflective to transparent or from transparent to reflective.
20. The medium of claim 18, wherein the method further comprises:
predicting a disruption to a first RF beam based on a location of
the one or more reflector sections or the one or more transparent
sections corresponding to a second RF beam; and determining to
transmit the second RF beam at a given point in time when the first
RF beam is not to be transmitted.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 16/986,527, filed on Aug. 6, 2020, the disclosure of which is
incorporated herein by reference.
BACKGROUND
[0002] An antenna system in a high-altitude platform (HAP) node,
such as a balloon node, may provide coverage to a large area on the
ground using multiple access links between the HAP node and user
equipment. These links can be formed by transmitting a
communication beam from the HAP node toward a discrete user
terminal or node or toward some discrete point to cover a general
geographic area. In addition, backhaul links can be formed between
the HAP node and other HAP nodes and between the HAP node and
ground stations. These links may be formed by aiming communication
beams of each node pair towards each other. Multiple links may be
formed at the HAP node going in different directions.
BRIEF SUMMARY
[0003] Aspects of the disclosure provide for an antenna for
wireless communication. The antenna includes a spherical reflector
and one or more feeds. The spherical reflector includes an inner
portion made of material that reflects radiofrequency (RF) beams,
and an outer portion positioned on an edge of the inner portion,
the outer portion being made of metamaterials that can be
controlled to be reflective of or transparent to RF beams. The one
or more feeds is configured to form one or more RF beams reflected
off the spherical reflector.
[0004] In one example, the spherical reflector is less than a
hemisphere. In another example, the antenna is part of a
high-altitude platform. In a further example, the outer portion of
the spherical reflector is controlled using an electrical signal
applied to at least a part of the outer portion.
[0005] In yet another example, the outer portion of the spherical
reflector includes a plurality of metamaterials sections. In this
example, each metamaterials section of the plurality of
metamaterials sections is optionally independently controllable.
Also in this example, the antenna optionally also includes one or
more processors configured to form one or more RF beams using the
one or more feeds, and control at least a part of the outer portion
of the spherical reflector to reflect an RF beam of the one or more
RF beams or be transparent to the RF beam based on the one or more
RF beam. In this option, the one or more processors are optionally
also configured to determine one or more reflective sections of the
plurality of metamaterials sections or one or more transparent
sections of the plurality of metamaterials sections for each RF
beam of the one or more RF beams. Also in this option, the at least
a part of the outer portion of the spherical reflector is
optionally controlled based on a location of the antenna and one or
more target locations. In this additional option, the one or more
target locations includes a ground-based terminal and an airborne
terminal.
[0006] Other aspects of the disclosure provide for a method for
controlling an antenna system having a spherical reflector that
includes a plurality of metamaterials sections. The method includes
determining, by one or more processors, one or more radiofrequency
(RF) beams to be formed by the antenna system based on a location
of the antenna system of a terminal and a target location;
determining, by the one or more processors, one or more reflector
sections or one or more transparent sections in the plurality of
metamaterials sections for the one or more RF beams; applying, by
the one or more processors, an electrical signal to one or more of
the plurality of metamaterials sections to cause the one or more of
the metamaterials sections to become reflective of or transparent
to an RF beam according to the one or more reflector sections and
the one or more transparent sections; and causing, by the one or
more processors, the antenna system to transmit the one or more RF
beams.
[0007] In one example, the determining of the one or more reflector
sections or the one or more transparent sections is based on a
location of the antenna system and one or more target locations. In
this example, the one or more target locations optionally includes
a ground-based terminal and an airborne terminal. In another
example, the electrical signal is a first electrical signal applied
at a first point in time, and the method also includes applying, by
the one or more processors, a second electrical signal at a second
point in time after the first point in time to switch the one or
more of the metamaterials sections from reflective to transparent
or from transparent to reflective.
[0008] In a further example, the method also includes predicting,
by the one or more processors, a disruption to a first RF beam
based on a location of the one or more reflector sections or the
one or more transparent sections corresponding to a second RF beam;
and determining, by the one or more processors, to transmit the
second RF beam at a given point in time when the first RF beam is
not to be transmitted. In yet another example, the spherical
reflector is less than a hemisphere. In a still further example,
the spherical reflector is a whole sphere.
[0009] Further aspects of the disclosure provide for a
non-transitory computer readable medium on which instructions are
stored. The instructions, when executed by one or more processors
in a high-altitude platform (HAP) node, cause the one or more
processors to perform a method for controlling an antenna system.
The method includes determining one or more radiofrequency (RF)
beams to be formed by the antenna system based on a location of the
HAP and a target location, the antenna system including a spherical
reflector including a plurality of metamaterials sections;
determining one or more reflector sections or one or more
transparent sections in the plurality of metamaterials sections for
the one or more RF beams; applying an electrical signal to one or
more of the plurality of metamaterials sections to cause the one or
more of the metamaterials sections to become reflective of or
transparent to an RF beam according to the one or more reflector
sections and the one or more transparent sections; and causing, the
antenna system to transmit the one or more RF beams. In one
example, the electrical signal is a first electrical signal applied
at a first point in time, and the method also includes applying a
second electrical signal at a second point in time after the first
point in time to switch the one or more of the plurality of
metamaterials sections from reflective to transparent or from
transparent to reflective. In another example, the method also
includes predicting a disruption to a first RF beam based on a
location of the one or more reflector sections or the one or more
transparent sections corresponding to a second RF beam; and
determining to transmit the second RF beam at a given point in time
when the first RF beam is not to be transmitted.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a functional diagram of an example system in
accordance with aspects of the technology.
[0011] FIG. 2 illustrates a balloon configuration in accordance
with aspects of the technology.
[0012] FIG. 3 is an example of a balloon platform with lateral
propulsion in accordance with aspects of the technology.
[0013] FIG. 4 is an example payload arrangement in accordance with
aspects of the technology.
[0014] FIG. 5 is an example antenna system in accordance with
aspects of the technology.
[0015] FIG. 6 is another view of the example antenna system of FIG.
5 in accordance with aspects of the technology.
[0016] FIG. 7 is a flow diagram of a method in accordance with
aspects of the technology.
DETAILED DESCRIPTION
Overview
[0017] The technology relates to an antenna system that includes
metamaterials configured to switch between reflecting an RF beam or
allowing an RF beam to pass through depending on an electrical
signal. In particular, portions of a reflector of the antenna
system may be comprised of metamaterials. Using this type of
metamaterial may make it possible to configure a spherical
reflector to cover a larger angular area. For example, the
spherical reflector including the metamaterials may be used to
generate beams more than 50 elevational degrees away from a
boresight of the antenna system, such as 70-80 elevational degrees
away. The spherical reflector may be part of a high-altitude
platform (HAP) terminal that provides access or backhaul coverage
to a geographic area.
[0018] The antenna system may include a spherical reflector and one
or more feeds. An inner portion of the spherical reflector may be a
reflective portion that is made of a material that reflects RF
beams and an outer portion arranged on the edge of the inner
portion may be made of metamaterials that can be reflective or
transparent to RF beams. The outer portion may comprise a plurality
of sections that may be controlled independently of each other. The
one or more feeds may be configured to emit one or more RF beams to
be reflected off the spherical reflector. The one or more feeds may
electronically and/or physically steer the one or more RF
beams.
[0019] One or more processors may be configured to direct the one
or more feeds to form RF beams based on a location of the antenna
system and one or more target locations. The one or more target
locations may include locations in the geographic area or locations
in the air. In particular, the one or more target locations may
include locations of user equipment or terrestrial terminals in the
geographic area or locations of airborne terminals. The one or more
processors may also be configured to apply an electrical signal to
at least a section of the outer portion of metamaterials based on
the RF beams to be formed by the one or more feeds. Namely, the one
or more processors may determine one or more reflector sections
and/or one or more transparent sections for each RF beam to be
formed. The electrical signal may be applied to the at least a
section of the outer portion to cause the metamaterials in the
section of the outer portion to become transparent when the
corresponding RF beam is to be transmitted. At a later time, when
the section of the outer portion is supposed to be a reflector
section, the electrical signal may be applied to cause the
metamaterials in the section to become reflective.
[0020] The technology described herein may create an RF antenna
system that has a wider range of coverage, such as an angular
coverage area of greater than 100 elevational degrees (>.+-.50
elevational degrees). Fewer moving parts may be used for the RF
antenna system, which may lower the possible pointing errors of RF
beams. In addition, a greater capacity for electronic steering
means less need for repositioning the reflector, allowing for
providing more continuous high gain. A larger geographic area may
therefore be served by a single HAP terminal equipped with such an
RF antenna system.
Example Networks
[0021] FIG. 1 depicts an example system 100 in which a fleet of
balloons or other high-altitude platforms described above may be
used. This example should not be considered as limiting the scope
of the disclosure or usefulness of the features described herein.
System 100 may be considered a balloon network. In this example,
balloon network 100 includes a plurality of devices, such as
balloons 102A-F as well as ground-based stations 106 and 112.
Balloon network 100 may also include a plurality of additional
devices, such as various devices supporting a telecommunication
service (not shown) as discussed in more detail below or other
systems that may participate in the network.
[0022] The devices in system 100 are configured to communicate with
one another. As an example, the balloons may include communication
links 104 and/or 114 in order to facilitate intra-balloon
communications. By way of example, links 114 may employ radio
frequency (RF) signals (e.g., millimeter wave transmissions) while
links 104 employ free-space optical transmission. Alternatively,
all links may be RF, optical, or a hybrid that employs both RF and
optical transmission. In this way balloons 102A-F may collectively
function as a mesh network for data communications. At least some
of the balloons may be configured for communications with
ground-based stations 106 and 112 via respective links 108 and 110,
which may be RF and/or optical links.
[0023] In one scenario, a given balloon 102 may be configured to
transmit an optical signal via an optical link 104. Here, the given
balloon 102 may use one or more high-power light-emitting diodes
(LEDs) to transmit an optical signal. Alternatively, some or all of
the balloons 102 may include laser systems for free-space optical
communications over the optical links 104. Other types of
free-space communication are possible. Further, in order to receive
an optical signal from another balloon via an optical link 104, the
balloon may include one or more optical receivers.
[0024] The balloons may also utilize one or more of various RF
air-interface protocols for communication with ground-based
stations via respective communication links. For instance, some or
all of balloons 102A-F may be configured to communicate with
ground-based stations 106 and 112 via RF links 108 using various
protocols described in IEEE 802.11 (including any of the IEEE
802.11 revisions), cellular protocols such as GSM, CDMA, UMTS,
EV-DO, WiMAX, and/or LTE, 5G and/or one or more proprietary
protocols developed for long distance communication, among other
possibilities. In one example using LTE communication, the base
stations may be Evolved Node B (eNodeB) base stations. In another
example, they may be base transceiver station (BTS) base stations.
These examples are not limiting.
[0025] In some examples, the links may not provide a desired link
capacity for HAP-to-ground communications. For instance, increased
capacity may be desirable to provide backhaul links from a
ground-based gateway. Accordingly, an example network may also
include balloons, which could provide a high-capacity air-ground
link between the various balloons of the network and the ground
base stations. For example, in balloon network 100, balloon 102F
may be configured to directly communicate with station 112.
[0026] Like other balloons in network 100, balloon 102F may be
operable for communication (e.g., RF or optical) with one or more
other balloons via link(s) 104. Balloon 102F may also be configured
for free-space optical communication with ground-based station 112
via an optical link 110. Optical link 110 may therefore serve as a
high-capacity link (as compared to an RF link 108) between the
balloon network 100 and the ground-based station 112. Balloon 102F
may additionally be operable for RF communication with ground-based
stations 106. In other cases, balloon 102F may only use an optical
link for balloon-to-ground communications.
[0027] The balloon 102F may be equipped with a specialized, high
bandwidth RF communication system for balloon-to-ground
communications, instead of, or in addition to, a free-space optical
communication system. The high bandwidth RF communication system
may take the form of an ultra-wideband system, which may provide an
RF link with substantially the same capacity as one of the optical
links 104.
[0028] In a further example, some or all of balloons 102A-F could
be configured to establish a communication link with space-based
satellites and/or other types of HAPs (e.g., drones, airplanes,
airships, etc.) in addition to, or as an alternative to, a ground
based communication link. In some embodiments, a balloon may
communicate with a satellite or a high-altitude platform via an
optical or RF link. However, other types of communication
arrangements are possible.
[0029] As noted above, the balloons 102A-F may collectively
function as a mesh network. More specifically, since balloons
102A-F may communicate with one another using free-space optical
links or RF links, the balloons may collectively function as a
free-space optical or RF mesh network. In a mesh-network
configuration, each balloon may function as a node of the mesh
network, which is operable to receive data directed to it and to
route data to other balloons. As such, data may be routed from a
source balloon to a destination balloon by determining an
appropriate sequence of links between the source balloon and the
destination balloon.
[0030] The network topology may change as the balloons move
relative to one another and/or relative to the ground. Accordingly,
the balloon network 100 may apply a mesh protocol to update the
state of the network as the topology of the network changes.
Balloon network 100 may also implement station-keeping functions
using winds and altitude control or lateral propulsion to help
provide a desired network topology. For example, station-keeping
may involve some or all of balloons 102A-F maintaining and/or
moving into a certain position relative to one or more other
balloons in the network (and possibly in a certain position
relative to a ground-based station or service area). As part of
this process, each balloon may implement station-keeping functions
to determine its desired positioning within the desired topology,
and if necessary, to determine how to move to and/or maintain the
desired position. For instance, the balloons may move in response
to riding a wind current, or may move in a circular or other
pattern as they station keep over a region of interest.
[0031] The desired topology may vary depending upon the particular
implementation and whether or not the balloons are continuously
moving. In some cases, balloons may implement station-keeping to
provide a substantially uniform topology where the balloons
function to position themselves at substantially the same distance
(or within a certain range of distances) from adjacent balloons in
the balloon network 100. Alternatively, the balloon network 100 may
have a non-uniform topology where balloons are distributed more or
less densely in certain areas, for various reasons. As an example,
to help meet the higher bandwidth demands, balloons may be
clustered more densely over areas with greater demand (such as
urban areas) and less densely over areas with lesser demand (such
as over large bodies of water). In addition, the topology of an
example balloon network may be adaptable allowing balloons to
adjust their respective positioning in accordance with a change in
the desired topology of the network.
[0032] Other than balloons, other high-altitude platforms, such as
drones, may fly routes in an autonomous manner, carry cameras for
aerial photography, and transport goods from one place to another.
The terms "unmanned aerial vehicle (UAV)" and "flying robot" are
often used as synonyms for a drone. The spectrum of applications is
broad, including aerial monitoring of industrial plants and
agriculture fields as well as support for first time responders in
case of disasters. For some applications, it is beneficial if a
team of drones rather than a single drone is employed. Multiple
drones can cover a given area faster or take photos from different
perspectives at the same time.
[0033] The balloons of FIG. 1 may be high-altitude balloons that
are deployed in the stratosphere. As an example, in a high-altitude
balloon network, the balloons may generally be configured to
operate at stratospheric altitudes, e.g., between 50,000 ft and
70,000 ft or more or less, in order to limit the balloons' exposure
to high winds and interference with commercial airplane flights. In
order for the balloons to provide a reliable mesh network in the
stratosphere, where winds may affect the locations of the various
balloons in an asymmetrical manner, the balloons may be configured
to move latitudinally and/or longitudinally relative to one another
by adjusting their respective altitudes, such that the wind carries
the respective balloons to the respectively desired locations.
Lateral propulsion may also be employed to affect the balloon's
path of travel.
[0034] In an example configuration, the high altitude balloon
platforms include an envelope and a payload, along with various
other components. FIG. 2 is one example of a high-altitude balloon
200, which may represent any of the balloons of FIG. 1. As shown,
the example balloon 200 includes an envelope 202, a payload 204 and
a coupling member (e.g., a down connect) 206 therebetween. At least
one gore panel forms the envelope, which is configured to maintain
pressurized lifting gas therein. For instance, the balloon may be a
superpressure balloon. A top plate 208 may be disposed along an
upper section of the envelope, while a base plate 210 may be
disposed along a lower section of the envelope opposite the top
place. In this example, the coupling member 206 connects the
payload 204 with the base plate 210.
[0035] The envelope 202 may take various shapes and forms. For
instance, the envelope 202 may be made of materials such as
polyethylene, mylar, FEP, rubber, latex or other thin film
materials or composite laminates of those materials with fiber
reinforcements imbedded inside or outside. Other materials or
combinations thereof or laminations may also be employed to deliver
required strength, gas barrier, RF and thermal properties.
Furthermore, the shape and size of the envelope 202 may vary
depending upon the particular implementation. Additionally, the
envelope 202 may be filled with different types of gases, such as
air, helium and/or hydrogen. Other types of gases, and combinations
thereof, are possible as well. Shapes may include typical balloon
shapes like spheres and "pumpkins", or aerodynamic shapes that are
symmetric, provide shaped lift, or are changeable in shape. Lift
may come from lift gasses (e.g., helium, hydrogen), electrostatic
charging of conductive surfaces, aerodynamic lift (wing shapes),
air moving devices (propellers, flapping wings, electrostatic
propulsion, etc.) or any hybrid combination of lifting
techniques.
[0036] In order to change lateral positions or velocities, the
platform may include a lateral propulsion system. FIG. 3
illustrates one example configuration 300 of a balloon platform
with propeller-based lateral propulsion, which may represent any of
the balloons of FIG. 1. As shown, the example 300 includes an
envelope 302, a payload 304 and a down connect member 306 disposed
between the envelope 302 and the payload 304. Cables or other
wiring between the payload 304 and the envelope 302 may be run
within the down connect member 306. One or more solar panel
assemblies 308 may be coupled to the payload 304 or another part of
the balloon platform. The payload 304 and the solar panel
assemblies 308 may be configured to rotate about the down connect
member 306 (e.g., up to 360.degree. rotation), for instance to
align the solar panel assemblies 308 with the sun to maximize power
generation. Example 300 also illustrates a lateral propulsion
system 310. While this example of the lateral propulsion system 310
is one possibility, the location could also be fore and/or aft of
the payload section 304, or fore and/or aft of the envelope section
302, or any other location that provides the desired thrust
vector.
Example Systems
[0037] According to one example shown in FIG. 4, a payload 400 of a
balloon platform includes a control system 402 having one or more
processors 404 and on-board data storage in the form of memory 406.
Memory 406 stores information accessible by the processor(s) 404,
including instructions that can be executed by the processors. The
memory 406 also includes data that can be retrieved, manipulated or
stored by the processor. The memory can be of any non-transitory
type capable of storing information accessible by the processor,
such as a hard-drive, memory card (e.g., thumb drive or SD card),
ROM, RAM, and other types of write-capable, and read-only memories.
The instructions can be any set of instructions to be executed
directly, such as machine code, or indirectly, such as scripts, by
the processor. In that regard, the terms "instructions,"
"application," "steps" and "programs" can be used interchangeably
herein. The instructions can be stored in object code format for
direct processing by the processor, or in any other computing
device language including scripts or collections of independent
source code modules that are interpreted on demand or compiled in
advance. The data can be retrieved, stored or modified by the one
or more processors 404 in accordance with the instructions.
[0038] The one or more processors 404 can include any conventional
processors, such as a commercially available CPU. Alternatively,
each processor can be a dedicated component such as an ASIC,
controller, or other hardware-based processor. Although FIG. 4
functionally illustrates the processor(s) 404, memory 406, and
other elements of the control system 402 as being within the same
block, the system can actually comprise multiple processors,
computers, computing devices, and/or memories that may or may not
be stored within the same physical housing. For example, the memory
can be a hard drive or other storage media located in a housing
different from that of the control system 402. Accordingly,
references to a processor, computer, computing device, or memory
will be understood to include references to a collection of
processors, computers, computing devices, or memories that may or
may not operate in parallel.
[0039] The payload 400 may also include various other types of
equipment and systems to provide a number of different functions.
For example, as shown the payload 400 includes one or more
communication systems 408, which may transmit signals via RF and/or
optical links as discussed above. By way of example only, the
communication system 408 may provide LTE or other
telecommunications services. The communication system(s) 408 may
include communication components such as one or more transmitters
and receivers (or transceivers 418) and an antenna system 420
having one or more antennas. The one or more processors 404 may
control the entire communication system 408.
[0040] Returning to FIG. 4, the payload 400 is illustrated as also
including a power supply 410 to supply power to the various
components of balloon. The power supply 410 could include one or
more rechargeable batteries or other energy storage systems like
capacitors or regenerative fuel cells. In addition, the payload 400
may include a power generation system 412 in addition to or as part
of the power supply. The power generation system 412 may include
solar panels, stored energy (hot air), relative wind power
generation, or differential atmospheric charging (not shown), or
any combination thereof, and could be used to generate power that
charges and/or is distributed by the power supply 410.
[0041] The payload 400 may additionally include a positioning
system 414. The positioning system 414 could include, for example,
a global positioning system (GPS), an inertial navigation system,
and/or a star-tracking system. The positioning system 414 may
additionally or alternatively include various motion sensors (e.g.,
accelerometers, magnetometers, gyroscopes, and/or compasses).
[0042] Payload 400 may include a navigation system 416 separate
from, or partially or fully incorporated into the control system
402. The navigation system 416 may implement station-keeping
functions to maintain position within and/or move to a position in
accordance with a desired topology or other service requirement. In
particular, the navigation system 416 may use wind data (e.g., from
onboard and/or remote sensors) to determine altitudinal and/or
lateral positional adjustments that result in the wind carrying the
balloon in a desired direction and/or to a desired location.
Lateral positional adjustments may also be handled directly by a
lateral positioning system that is separate from the payload.
Alternatively, the altitudinal and/or lateral adjustments may be
computed by a central control location and transmitted by a ground
based, air based, or satellite based system and communicated to the
high-altitude balloon. In other embodiments, specific balloons may
be configured to compute altitudinal and/or lateral adjustments for
other balloons and transmit the adjustment commands to those other
balloons.
[0043] The navigation system is able to evaluate data obtained from
onboard navigation sensors, such as an inertial measurement unit
(IMU) and/or differential GPS, received data (e.g., weather
information), and/or other sensors such as health and performance
sensors (e.g., a force torque sensor) to manage operation of the
balloon's systems. When decisions are made to activate the lateral
propulsion system, for instance to station keep, the navigation
system then leverages received sensor data for position, wind
direction, altitude and power availability to properly point the
propeller and to provide a specific thrust condition for a specific
duration or until a specific condition is reached (e.g., a specific
velocity or position is reached, while monitoring and reporting
overall system health, temperature, vibration, and other
performance parameters).
[0044] The antenna system may include a spherical reflector and one
or more feeds. The shape of the spherical reflector may be a
hemisphere (or 50% of a surface are of a sphere), or less than a
hemisphere, such as 20% of a surface area of a sphere. In some
implementations, the spherical reflector may be a whole sphere. An
inner portion of the spherical reflector may be a reflective
portion that is made of a material that reflects RF beams, such as
beams having a frequency of 2100 MHz, 3500 MHz, or other frequency,
and an outer portion arranged on the edge of the inner portion may
be made of metamaterials that can be reflective or transparent to
RF beams. As shown in FIG. 5, for spherical reflector 502, inner
portion 504 is the reflective portion, and outer portion 506 is the
metamaterials portion. The outer portion may comprise a plurality
of sections that may be controlled independently of each other. For
example, the outer portion 506 may be constructed of a plurality of
metamaterials sections that can be independently controlled. Every
metamaterials section may be a same shape, such as a curved
rectangular piece, arranged to form a portion of a sphere for the
outer portion of the spherical reflector 502. From the side view
shown in FIG. 5, two rows of metamaterials sections are visible,
with each row showing twelve sections. The opposite half may have
the same configuration. In some alternatives, the metamaterials
portion may be one or more sections of metamaterials that is
controlled as one unit.
[0045] The one or more feeds may include a first feed and a second
feed. The first feed and the second feed may each be configured to
emit an RF beam to be reflected off the spherical reflector. The
first feed and the second feed may be configured to electronically
steer the respective RF beams. In some implementations, the first
feed and the second feed may also be configured to move independent
of the other. As shown in FIG. 6, antenna system 420 has first feed
508 and second feed 510 configured to emit a first RF beam 512 and
a second RF beam 514, respectively. For example, first feed 508 is
configured to direct the first RF beam 512 towards spherical
reflector 502. The first RF beam 512 is reflected off the spherical
reflector 502 and out towards a first target location. The second
feed 510 is configured to direct the second RF beam 514 towards
spherical reflector 502. The second RF beam 514 is reflected off
the spherical reflector 502 and out towards a second target
location.
Example Methods
[0046] In addition to the operations described above and
illustrated in the figures, various operations will now be
described. It should be understood that the following operations do
not have to be performed in the precise order described below.
Rather, various steps can be handled in a different order or
simultaneously, and steps may also be added or omitted.
[0047] One or more processors of the control system or one or more
processors in the payload dedicated to controlling the one or more
communication systems may determine one or more RF beams to be
formed by the one or more feeds in the antenna system based on a
location of the antenna system and one or more target locations.
The one or more beams may be configured to reflect off the
spherical reflector at least once and out into free space. Beam
characteristics, such as a size, a shape, and a direction of each
beam, may also be determined by the one or more processors. Beam
characteristics may be determined based on the location of the
antenna system, the one or more target locations, population
density, history of demand, location or density of other terminals
(terrestrial towers, other HAPs, etc.) providing coverage in or
near the area, settings or constraints of the other terminals,
regulations for the operation of a particular network, or other
network factors. The one or more target locations may include
locations in the geographic area or locations in the air. In
particular, the one or more target locations may include locations
of user equipment or terrestrial terminals in the geographic area
or locations of airborne terminals. Additionally or alternatively,
the one or more target locations include a region that is defined
and selected based on population density, history of demand,
location or density of other terminals (terrestrial towers, other
HAPs, etc.) providing coverage in or near the area, settings or
constraints of the other terminals, regulations for the operation
of a particular network, or other network factors.
[0048] For example, the one or more processors 404 may determine
that the first and second feeds 508, 510 are to form the respective
RF beams 512, 514 based on a location of the payload carrying the
antenna system 420 and the first and second target locations for
the respective beams. The location of the payload may be determined
using the positioning system 414. In this example, the location of
the payload may be that of balloon 102B in FIG. 1, between
ground-based station 106 and balloon 102E. From this location, the
antenna system 420 may form link 108 with ground-based station 106
and/or link 104 with balloon 102E. The first RF beam 512 may be
determined to be transmitted by the first feed 508 from a HAP
terminal to a first location of the geographic area and a second RF
beam 514 may be determined to be transmitted by the second feed 510
to a second location of an airborne terminal. The first location
may be that of the ground-based station 106, and the second
location may be the balloon 102E. The first RF beam may be
configured to provide an access link of a network to one or more
user equipment. The second RF beam may be configured to provide a
backhaul link for the network. In some implementations, the second
RF beam is a different frequency band than the first RF beam.
[0049] The one or more processors may determine one or more
reflector sections and/or one or more transparent sections of the
metamaterials portion of the spherical reflector for each RF beam
to be formed the one or more feeds. For example, for the first RF
beam 512, there may be no reflector sections and no transparent
sections because the first RF beam 512 is planned to reflect off
the inner portion 504 of the spherical reflector 502 and is not
planned to intersect with any section of the spherical reflector
after reflecting off the inner portion. For the second RF beam 514,
there may be a plurality of transparent sections according to where
the second RF beam 514 is determined to intersect with the
spherical reflector at location 602 after reflecting off the inner
portion 504. One or more metamaterials sections corresponding to
the area the second RF beam 514 intersects with the metamaterials
portion 506 may be determined to be the transparent sections based
on a size, a shape, and a direction of the second RF beam.
[0050] The one or more processors may be configured to apply an
electrical signal to one or more metamaterials sections to cause
the one or more metamaterials sections to become reflective or
transparent according to the one or more reflector sections and the
one or more transparent sections. For example, an electrical signal
may be applied to the area of the metamaterials portion 506 of
spherical reflector 502 to cause the metamaterials in the area to
become transparent when the second RF beam 514 is to be
transmitted. At a later time, when the area is determined to be
part of a reflector section, the electrical signal may be applied
to cause the metamaterials in the area to become reflective.
[0051] In some scenarios, a configuration of the outer portion of
metamaterials for the second RF beam may cause a disruption to the
first RF beam. In other words, for the second RF beam to transmit
to the second location, the first RF beam would not be able to
transmit to the first location. For example, disruption may be
predicted to be caused when at least a section of metamaterials is
a transparent section for the second RF beam but a reflective
section for the first RF beam. The one or more processors may
determine that the one or more target locations may include the
second location, and not the first location, at a given point in
time. Alternatively, the one or more processors may determine that
the second location takes priority over the first location at the
given point in time. The one or more processors may ignore the
first RF beam in determining the one or more reflector section and
the one or more transparent sections for the second RF beam for the
given point in time. The disruption to the first RF beam is
inconsequential. In addition, the one or more processors may
deactivate the first feed during the given point in time.
[0052] The one or more processors may then cause the antenna system
to transmit the one or more RF beams. The first feed 508 may
transmit the first RF beam 512, which is reflected off the inner
portion 504 of the spherical reflector 502 and out through free
space towards the ground-based station 106. The second feed 510 may
transmit the second RF beam 514, which is reflected off the inner
portion 504 of the spherical reflector 502. The second RF beam 514
is then reflected out partially through free space and partially
through the one or more transparent sections of the metamaterials
portion 506 of the spherical reflector 502 towards balloon
102E.
[0053] In some scenarios, the one or more processors may determine
that there are no reflector sections and no transparent sections of
the metamaterials portion for the one or more RF beams to be
formed. For example, in one scenario, the one or more processors
may determine that there is no intersection of any RF beam with the
metamaterials portion of the spherical reflector. As a result, the
one or more processors may cause the antenna system to transmit the
one or more RF beams without making any changes to the
metamaterials portion of the spherical reflector.
[0054] FIG. 7 shows an example flow diagram in accordance with
aspects of the technology. More specifically, FIG. 7 shows a flow
of an example method 700 for controlling an antenna system having a
spherical reflector that includes a plurality of metamaterials
sections. At block 702, one or more processors may determine one or
more RF beams to be formed by the antenna system of a terminal
based on a location of the terminal and a target location. At block
704, the one or more processors may determine one or more reflector
sections or one and/or one or more transparent sections in the
plurality of metamaterials sections of the antenna system for the
one or more RF beams. At block 706, the one or more processors may
apply an electrical signal to one or more of the plurality of
metamaterials sections to cause the one or more of the plurality of
metamaterials sections to become reflective or transparent
according to the one or more reflector sections and the one or more
transparent sections. At block 708, the one or more processors may
cause the antenna system to transmit the one or more RF beams.
[0055] The technology described herein may create an RF antenna
system that has a wider range of coverage, such as an angular
coverage area of greater than 100 elevational degrees (>.+-.50
elevational degrees). Fewer moving parts may be used for the RF
antenna system, which may lower the possible pointing errors of RF
beams. In addition, a greater capacity for electronic steering
means less need for repositioning the reflector, allowing for
providing more continuous high gain. A larger geographic area may
therefore be served by a single HAP terminal equipped with such an
RF antenna system.
[0056] Unless otherwise stated, the foregoing alternative examples
are not mutually exclusive, but may be implemented in various
combinations to achieve unique advantages. As these and other
variations and combinations of the features discussed above can be
utilized without departing from the subject matter defined by the
claims, the foregoing description of the embodiments should be
taken by way of illustration rather than by way of limitation of
the subject matter defined by the claims. In addition, the
provision of the examples described herein, as well as clauses
phrased as "such as," "including" and the like, should not be
interpreted as limiting the subject matter of the claims to the
specific examples; rather, the examples are intended to illustrate
only one of many possible embodiments. Further, the same reference
numbers in different drawings can identify the same or similar
elements.
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