Shrinking and Rethinking the Old Vertical Antenna.


Mar 11, 2001
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March 7, 2002

Shrinking and Rethinking the Old Vertical Antenna.


s cellphones start to approach the size of matchboxes, their antennas are shrinking, too. In the tiniest new phones the antenna is often hidden inside, where it may take the form of a piece of foil or a coiled wire. But a new material may allow antennas for phones and other devices to become both obvious and invisible at the same time.

The material was invented by Tom A. Aisenbrey, general manager at Integral Technologies, a tiny company with offices in Bellingham, Wash., and Vancouver, British Columbia. While working on a more traditional antenna, he stumbled across a way to mix a metallic compound with plastic or rubber to make a conductive material that can be molded into any shape. That makes it possible to create phones in which the plastic case serves as the antenna.

Because the material is such an effective conductor, it reduces the amount of battery power needed to send a signal and offers better reception than a traditional antenna, Integral says.

Mr. Aisenbrey has been trying out prototype antennas on his own cellphone for months. He said that the antenna he is now using is a careful blend of silicone and his metallic compound, the ingredients of which are a company secret. The silicone casing makes a good shock absorber if the phone is dropped, he said, and the antenna can pull in a signal even in deep valleys where reception may ordinarily be poor. Integral says that the manufacturing costs of the new antennas will be the same as or less than those of traditional metal ones.

Lothar Schmidt, a technical manager at Cetecom, a company that was hired by Integral to assess the antenna, said tests had shown that in some cases the new antenna more than doubled a cellphone's outgoing signal strength.

Integral is working with GE Plastics to help it develop and market the material, and the two companies are talking to several cellphone makers about using it in their products, said William Robinson, Integral's chief executive.

Of course, there are other gadgets that could benefit from better antennas, like those that make use of the short-range wireless standard Bluetooth and the Global Positioning System, the satellite network that allows users to plot precise locations. Integral is even talking to a provider of satellite tracking services about turning truck bumpers into giant antennas by making them out of a rubbery blend of the new material. The antennas would improve communication with low-orbit satellites that allow the company to report the location of a truck and status information back to its clients.

The bumpers will need some exposure to the open sky to communicate with the satellites. But unlike a cellphone network, the tracking system does not need to remain in constant contact to do its job, so it is not a crisis if the signal is temporarily blocked by tunnels or buildings.

Mr. Robinson said that Integral also planned to make flat antenna strips that could be attached to the sides of shipping containers so that they could be tracked the same way. The strips will be an improvement over standard metal antennas, which are often targets for vandals or are accidentally broken off, he said.

Mr. Aisenbrey said that the same principle could be applied to cars, where "you could turn the gasket of your windshield into an antenna." Or manufacturers could build an antenna into the surface of a boat's deck.

The United States military has taken a similar approach by building metal antennas into the structural frame of airplanes. SkyCross, a company based in Melbourne, Fla., that has developed commercial applications for some military communications technology, is working to apply the concept to cars and perhaps buildings.

When the antenna is structurally embedded in a car, it becomes "a very effective radiator" of electromagnetic waves, said Alan L. Haase, chief executive of Skycross. An antenna built into the walls of a building could do the same thing, he said.

Skycross is also looking at technology that would allow it to "print" an antenna on the inside of a cellphone's case, Mr. Haase said.

Integral's invention shows that plastic, hardly a cutting-edge material, still has plenty of untapped high-tech potential.

Researchers have devoted much attention lately to conductive plastics, which, unlike Integral's material, do not require any metal to make them effective carriers of electric current. The technology is already being used to create moldable plastic batteries for electronic products. For example, NEC released a laptop last year with a lithium-polymer battery wrapped around the back of its screen.

Blends of plastic and metal compounds similar to the one in Integral's antenna are often found in military equipment, where they act as shielding material to keep enemy sensors from spotting sources of electromagnetic energy. They can also shield people from energy sources in computers and other devices.

Mr. Aisenbrey said that Integral's innovation was to tweak the blend to make it conductive enough for use as an antenna — in effect, turning a barricade into a pathway.

Experts on antenna design said that Integral's technology sounded interesting but that they would need more information to evaluate it. They noted that other researchers were also looking to novel materials as a way to boost antenna performance.

Dr. David M. Pozar, professor of electrical and computer engineering at the University of Massachusetts and a researcher in the school's Antenna Laboratory, questioned Integral's emphasis on seeking to patent its technology.

"Patents in the antenna area, by themselves, do not ensure the success of a product, and it is usually very easy to circumvent patents" in this field, Dr. Pozar said. Performance and price rather than patents are the keys to success, he added.
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