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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.