Production Group: Antenna
The cellular phone needs many components to make it work properly. There are chips, buttons, speakers and many more, but it would not be complete without an antenna. “The antenna forms the interface between the communication device and the outside world” (Davis and Perrotta 1). It is important to make the connection to let people talk to each other. The antenna is forever being advanced in helping people get the clear calls they desire.
The antenna has its roots in Japan, where Professor Hidetsugu Yagi and Shintaro Uda were the first people to design and construct an antenna (Sivowitch 1). The Yagi-Uda antenna, or Yagi, was first applied to radios, point-to-point communications, radar, and televisions (Sivowitch 1). In 1932, the Yagi came to the United States and was placed on televisions before the end of the decade. It became more widespread in the 1940’s and 1950’s (Sivowitch 2). Guglielmo Marconi, an Italian physicist, developed the idea of using the antenna for wireless communication. He also discovered that a wire could transmit farther than a small metal cylinder (“Antenna” 142). Eventually it was applied to the cellular phone. Constant advances have made the antenna powerful and efficient.
The antenna is very complex and has many forms. Generally, it is a “device for transmitting and receiving radio waves” (“Antenna” 141). The transmitting antennas change the electrical signals into electromagnetic waves, and spread them out (“Antenna” 141). Depending on the type of antenna, there can be different types of waves, different distances, etc. (Antenna 1). These signals go out to the receiving antennas on the cellular phones of millions of people. The electromagnetic field is spread out over the span of the antenna to receive the signal (What is an antenna and how does it work 1). “Wherever this wave comes in contact with a receiving antenna, it induces a small electric current in it that alternates back and forth along the antenna in time with the oscillations of the wave” (“Antenna” 141). This means that the wave vibrates the antenna and transforms the waves into, in the case of cellular phones, voices. The longer the antenna the longer the waves it transmits or receives, and vice versa (Antenna 1). This means that the transmitting antenna and the receiving antenna need to be correlated in size so that they can communicate with each other properly.
There are many materials and types of antennas. “The simplest form of antenna is a single elevated wire with an earth connection” (“Antenna” 142). Dipole antennas are “merely rods of very specific lengths that radiate energy in all directions” (Cooper 2). One type of dipole antenna is the reflector plane antenna (Carr 1). This type of antenna is made with antenna wire, which is #14 standard copper-clad steel wire (Carr 1). The antenna needs the right materials to function effectively. “The material choices can have a great impact upon radio performance” (Davis and Perrotta 1). For a Motorola, the antenna has a “metallic conductor” covered in a “polymer coating or radome” (Davis and Perrotta 1). This “radome” material is selected based on specific requirements: flexibility, durability, and abrasion resistance (Davis and Perrotta 1).
A big idea that has developed recently is smart antennas. They are more useful than standard antennas because they, “customize and fine-tune antenna coverage patterns that match the traffic conditions in a wireless network or that are better suited for complex radio frequency environments” (Smart Antennas 1). The smart antenna was first applied for military uses, but it has evolved into the wireless communications market (Smart Antenna 1). These antennas allow flexibility for wireless network operators to adjust changing traffic patterns (Smart Antennas 1). Adaptive antenna arrays are advanced smart antennas. They allow for the best reception and at the same time, minimize interference by locating the source of the radio signal and amplifying just that signal (Cooper 2-3). These antennas are also fundamental to miniaturization. There is an emphasis on making cellular phones as small as possible, and the antenna size is part of this struggle. “‘Smart’ antenna technology can be combined with the newest techniques for antenna miniaturization to offer reduced size in communication-on-the-move applications” (Robinson 1-2). Some ideas that also may help with the miniaturization of antennas are different materials. Instead of using copper wire, other ferrites and dielectrics are being experimented with. They decelerate the electromagnetic wave, which allows them to function like a physically bigger antenna (Robinson 2).
There is an alternative to the traditional external antenna. The internal antenna is quickly becoming popular because of its ability to miniaturize cellular phones. “The internal antenna is a passive device designed to capture stray radiation in the body of the phone and re-radiate the signal to improve the phone's performance” (Antenna Booster 1). There are phones with just internal antennas, or phones with an antenna booster that helps amplify reception. The booster is an internal antenna, but it aids the external antenna, instead of replacing it.
Picture
of an internal antenna (Antenna Booster)
Graph
of the difference in signal strength with and without the internal antenna
(Internal
Antenna - Does it work?)
Results about the efficiency of internal antennas are diverse. Several tests were performed and produced the graph above. It shows that the booster helped to increase the strength of the signal, but it is not as strong as companies advertise; it is not as good as “adding a four foot antenna” (Internal Antenna - Does it work? 2). Using an internal antenna as an aid to the external one may have a positive effect, but just the internal antenna by itself may be worse than the external antennas. Miniaturization of the cellular phone is what most companies are working towards. But, parts can only get so small before problems arise. Instead of using antennas that pull out or are “stubby”, companies have looked to the internal antenna to meet consumers’ wants for small, sleeker cellular phones (JS Online 1). Research has shown that “the radio strength of today’s phones with internal antennas is 15% to 20% less powerful than that of phones with external antennas” (JS Online 1). The reception problem has kept Verizon Wireless from switching to internal antennas. They do not believe that they have the same capabilities as external antennas, so Verizon does not want their phones to have inferior reception, such as static and dropped calls (JS Online 2). Some experts believe that the internal antenna can never match the performance of a well-made external antenna (Reading 100). However, many companies are providing phones with the internal antenna. Customers complain that the external antennas often break, causing a major inconvenience (JS Online 1). Another problem is that external antennas hurt the ability to miniaturize cellular phones. Phones are progressively getting smaller, and the antenna seems to be in the way of reaching new heights in cellular phone technology. With the development of the internal antenna, cellular phones may be able to have new designs. Some think it is not effective enough, but the way technology is developing, it could eventually be better than the external antenna (JS Online 3). The whole market is constantly changing. It is conceivable to think that the internal antenna could soon play a major role in the cellular phone industry.
Engineers are always trying to improve materials and designs to better meet demands. The antenna is changing along with the rest of the cellular phone. There is always a new technology or material reshaping the antenna, and it will probably always be this way.
Works Citied
Antenna.
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Antenna Booster. 1999. PlusCellular. 25 Nov. 2003
<http://www.pluscellular.com/antenna_booster.htm>.
Carr, Joseph J. “All About Reflector Antennas.” Popular Electronics. Sept. 1996: 41. Academic Search Premier. EBSCO. U of Dayton Roesch Lib. 25 Oct. 2003 <http://search.epnet.com>.
Cooper, Martin. “Antennas Get Smart.” Scientific American. Jul. 2003: 48. Academic Search Premier. EBSCO. U of Dayton Roesch Lib. 25 Nov. 2003 <http://search.epnet.com>.
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Properties in Antenna
Performance. Motorola. 19 Nov. 2003
<http://rf.rfglobalnet.com/library/Papers/files/2/perrotta.htm>.
Internal Antenna - Does it work? 2001. 2 Dec. 2003
<http://www.geocities.com/techpro118/>.
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2003. New York
Times. 25 Nov. 2003
<http://www.jsonline.com/bym/tech/news/mar03/124359.asp?format=print>.
Reading, Leslie J. “Designing dual-band internal antennas.” EDN. 8 Nov. 2001: 99-103. Academic Search Premier. EBSCO. U of Dayton Roesch Lib. 25 Nov. 2003 <http://search.epnet.com>.
Robinson, Gail. “New materials Shrink Antenna.” Electronic Engineering Times. 3 Nov. 1997: 41. Academic Search Premier. EBSCO. U of Dayton Roesch Lib. 25 Oct. 2003 <http://search.epnet.com>.
Sivowitch, Elliot. Directive Short Wave Antenna, 1924.
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Institiution. 25 Nov. 2003
<http://www.ieee.org/organizations/history_center/milestones_photos/yagi.html>.
Smart Antennas. 2003. CDMA Development Group. 17 Nov.
2003
<http://www.cdg.org/technology/cdma_technology/smart_antennas/index.asp>.
What is an antenna and how does it work? 2002. gigaAnt.
25 Oct. 2003
<http://www.gigaant.com/antennabasics/basicknowhow,whatantenna.asp>.