dual antennas would boost cell1
TRANSCRIPT
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Dual Antennas Would Boost Cell-
Phone Signals
1st week
Introduction:
New design would mean fewer dropped calls, longer battery life.
The recent furor over the iPhone 4's antenna has made consumers
aware of the constraints designers face when trying to build sleek,
compact gadgets that also get a good connection. Researchers at
Rice University have come up with a design that could make signal
worries a thing of the past, and extend battery life as well. The
design uses two antennas that focus their power in different
directions
Radio circuit: This wireless transmitter has been connected to
three directional antennas, a setup that shows how cell phones
could save power by directing radio signals toward cell towers.
The antenna in your current cell phone beams a signal out
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in every direction. "Only a tiny fraction of that energy actually
reaches the base station," says Lin Zhong, whose research group
investigates ways to make computing devices more efficient. Not
only is this a waste of a cell phone's battery life, he says, but it
creates unnecessary interference for other users.
Antennas that beam out energy in a narrower band can be more
efficient. Cell towers use this tactic, with several antennas pointing
in different directions to better serve users. Zhong's group, in
collaboration with colleague Ashutosh Sabharwal, has developed a
prototype antenna system that could give that ability to cell phones
themselves, saving energy and extending battery life.
The researchers connected a small Wi-Fi transmitter to three cheap
directional "patch" antennas facing in different directions, as well
as a standard omni-directional antenna. Only one of the four was
active at any one time, with the directional antenna being used to
send data to the base station, and the omni-directional one used toreceive it.
The system was mounted on a motorized spinning platform to test
its most crucial quality: the ability to stay connected when the
orientation of the device changed as it rotated (by switching to
whichever antenna was generally oriented toward the base station).
The directional antennas monitored the quality of packets receivedfrom the base station to decide which among them should send the
next packet.
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2nd week
Even when spun at one revolution per second, the prototype could
stream video with almost zero interference. That suggests the
approach would work well in real situations, says Zhong. He
collected a week of data from the accelerometers and compasses of
11 smart phones actually in use by real people, and found that
these phones were rarely rotated at more than a third of a
revolution per second while connected.
The current prototype used Wi-Fi frequencies because off-the-shelf
directional Wi-Fi antennas are easier to acquire. But the results
apply to any frequency, says Zhong. His group is working on a
version that connects multiple antennas to Nexus One cell phones
running the Android operating system, as well as computer
simulations of the approach. Results so far back up the Wi-Fi tests,
he says.
All the results suggest that using just two antennas in a phone
would offer significant savings, says Zhong. "With one antenna on
the back and one on the front you could double the signal strength
at the edge of the network compared to a regular antenna, and
halve the energy needed when at the center of the network."
Spencer Webb, president of AntennaSys, a New Hampshire
company that designs antennas for everything from cell phones to
medical devices, agrees that two separate antennas front and back
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could help a cell phone in a variety of situations. "One example is
that when you place a device down on a surface, it could switch to
the uppermost antenna to avoid interference," says Webb.
Multiple antennas might also make it possible to sidestep the
problem of a user's grip hindering the connection, an issue many
are now familiar with thanks to the publicity surrounding Apple's
iPhone 4 launch, Webb adds. "If you had, say, dual antennas and
used them wisely, you could perhaps prevent some of those issues
by switching antenna when a person changes their hand position,"
he says.
However, one reason for the controversy over Apple's iPhone--
dubbed "antennagate"--is the tight constraints on space and design
in smart phones, Web adds. Devices like the Droid X and HTC
Evo have suggested that larger smart phones are becoming popular
with designers, says Webb. "But did they put more antenna space
in there? No."
Antenna engineers typically lose out in the battle for space to the
battery or other components, Webb says. Compact components
that offer large space savings will be needed for manufacturers to
make room for an extra antenna.
That could become possible as the necessary chips drop in cost and
size, and as cell-phone carriers move toward next generation
mobile networks, such as LTE and 4G, that use smaller antennas,
says Zhong, although the strategy may gain more immediate
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traction in other types of device. "In a laptop, for example, more
space like the back of the screen is available," says Webb.
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3rd week
How to Improve Cell Phone Reception
Over the past 20 years cell phone ownership has increased
massively, to the point where over 80% of the world's population
has cell phone coverage. The technology needed to provide
adequate signal has not kept up with demand, which is why 69% of
Americans have experienced dropped calls and poor signal.
However, with advances in technology there are ways to improve
cell reception.
Keep in mind, poor reception is not something that your service
provider will fix just because you want them to. It must be
justifiably cost effective for them to put up new towers, which will
ultimately be criticized by cities, home owners associations, etc.
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Most users think there is nothing they can do to improve their cell
phone reception by themselves. This is most certainly untrue, and
the following will explain what you can do to ensure great mobile
coverage without waiting for a new tower to magically appear.
Steps
Battery. Your cell phone uses a lot more power
when connecting a call than when it is on
standby. Often, your battery can be strong
enough to attempt a call, but not strong enough
to find a signal. If you find you are having signal
problems, try to keep your battery charged to 2
bars or higher.
Landscape. Buildings and other large structures
are very unfriendly to cell phone signal. Rather
than making calls from deep inside buildings try
moving outside or to a window to place your call.
If you are having reception problems on the
street try walking to the nearest intersection as
they typically have better coverage. Cellular
band radio waves do not effectively penetrate
earth: if you are underground you will likely
receive no signal.
Install a cellular repeater. If you are having
cell problems in one location, such as your home
or office, then try installing a cellular repeater.
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Cell phone repeaters pick up low cell signal with
an antenna, boost the signal and broadcast it
over the coverage area. They typically need at
least 2 bars of signal where the antenna isplaced (usually outside or on the roof) but can
substantially improve cell reception, as well as
battery life and data download speeds. Some
repeaters might need technical knowledge such
as the frequency of your carrier, and only work
for one service provider. For a less technical
approach that improves reception on all carriers,
use a dual-band cell phone repeater.
4th week
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Upgrade your antenna. A few cell phone
manufacturers make a "Hi-gain" antenna for
their handsets, which may be changed in-store
or by the user at home. Although these won’timprove signal as much (or at all) as a repeater
these antennas are relatively inexpensive and
you are not confined to one location.
Change networks. Most networks operate
independently of one another, using their ownfrequencies and constructing their own cell
phone towers. Chances are if the signal is bad
with one network you can improve by switching.
Most cellular networks these days allow you to
transfer your phone number when you change
provider.
Hold your phone correctly. Mobile phone
antennas are designed to project a signal
outward, perpendicular to the long axis of the
antenna. As such, mobile phones seek signals in
a donut-esque shape around the antenna.
Normally, when a mobile is held upright, this isnot a problem. However, if you are holding your
phone in a strange way, such as on its side or
upside down, you will hinder the operation of the
antenna. Hold your phone upright to guarantee
that your phone can "see" your carrier signal.
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Host a cell site. This may take time, but where
cell phone reception is inadequate property
owners can host small cell sites on theirproperties for major wireless carriers. 3rd parties
with Wireless Revenue Programs allow you to
register your property to be eligible. Then when
there is carrier interest in the area you'll be on
the short list of places they choose from and will
have optimal coverage. They may even pay your
phone bill.
Cellular repeater
A cellular repeater, cell phone repeater, or wireless cellular
signal booster, a type of bi-directional amplifier (BDA) as
commonly named in the wireless telecommunications industry, is a
device used for boosting the cell phone reception to the local area
by the usage of a reception antenna, a signal amplifier and aninternal rebroadcast antenna.
These are similar to the cellular broadcast towers used for
broadcasting by the network providers, but are much smaller,
usually intended for use in one building. Modern cellular repeater
amplifiers rebroadcast cellular signals inside the building.
The systems usually use an external, directional antenna to collect
the best cellular signal, which is then transmitted to an amplifier unit which amplifies the signal, and retransmits it locally,
providing significantly improved signal strength.
The more advanced models often also allow multiple cell phones
to use the same repeater at the The market for cellular repeaters is
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expected to grow rapidly over the coming years, particularly in the
USA. This is due to the combination of the poor network coverage
in some areas, and the large scale departure from the land-line
system.
The CTIA – The Wireless Association (formerly the Cellular
Telecommunications & Internet Association) had predicted that by
2007 30% of phone users in the US would be mobile only - more
than 60 million lines. This combined with the low population
density (compared with Europe and Japan) means that many
people will have to use some method to improve their home signal.
Other advantages of cellular repeaters include an increase in the
cell phone's battery life and a lower level of radiation emitted by
the handset - both caused by the lower power required to broadcast
the signal to the local bi-directional amplifier, due to its proximity
to the phone.