Insect-Like Antenna Helping Scientists Explore the Universe

BOULDER, Colo. — A spiral antenna the size of a grain of sand and made of gold may someday help reveal the origins of the universe, solve the enigma of global warming and diagnose mysterious human diseases.

As slim as a human hair, it is the world’s smallest antenna. It resembles the antennas that some insects have had for millions of years.

Scientists at the National Institute of Standards and Technology in Boulder have developed this electronic microantenna through the same techniques they use to make integrated circuits.

“What infrared technology has given civilization is the same capability that insects have: We’re able to see in the dark,” says physicist Donald G. McDonald, one of the three scientists who produced the antenna.

“Is that important? Ask anybody who was in the Persian Gulf War. It was of paramount importance there.”

Attached to an individual detector, the new microantenna can’t do much.

Its value, McDonald explains, will be demonstrated in large arrays of hundreds or thousands of detectors and antennas.

Besides national defense, the potential applications are numerous. Among them:

* In conjunction with powerful telescopes, antennas could play a role in exploring the universe, detecting infrared signals from far outer space and forming images from those signals.

* Mounted on spacecraft orbiting above the Earth’s atmosphere, they could continuously monitor atmospheric pollutants below, such as carbon monoxide. “To my mind,” McDonald told National Geographic, “the thing of greatest importance to civilization is studying things like pollution so that we can avoid some kind of future catastrophe.”

* In a medical laboratory, they could detect disease symptoms in the human body that are beyond the reach of today’s sophisticated equipment.

* Outside a skyscraper, they could measure exactly where heat is leaking.

The minuscule lithographic (photographically produced) antennas are capable of picking up infrared wavelengths six times shorter than those registered by previous antennas, according to the Boulder institute, which is part of the U.S. Commerce Department.

Contrasted with the vastly longer wavelengths--such as radio and television--at the other end of the electromagnetic spectrum, infrared wavelengths are short--only 3 to 30 microns. A micron is one-millionth of a meter.

Without the new antennas, which are about 60 microns wide, the superconducting detectors would be unable to sense infrared wavelengths. With the antennas, the detectors can “see” images of heat radiating from objects and organisms both on Earth and in space.

Electronic miniaturization, a technology that’s been around for a relatively few years, makes it possible. “You want to have greater and greater sensitivity to weaker and weaker signals,” McDonald says.

Other key members of the research team are scientists Erich N. Grossman and Joseph E. Sauvageau. Centuries ago, however, nature did much of their work for them.

Similar antennas evolved on insects that “see” in the dark, including such common species as mosquitoes, fire ants and cockroaches.

“If you go out and find 300 different types of man-made antennas, I’ll find some type of insect that has every one of those shapes,” says Phillip S. Callahan of Gainesville, Fla. “The only difference is that the man-made ones are made of metal.”

Callahan, a retired entomologist for the U.S. Agriculture Department, has been studying insect antennas since 1956. “I was doing this 25 or 30 years before the physicists thought about it,” he says. “I’ve got so much proof that it makes Einstein’s relativity look like it hasn’t been proved at all.”

The work in the Boulder laboratory has been supported in part by the Strategic Defense Initiative--”Star Wars”--through the Office of Naval Research and by the National Aeronautics and Space Administration.

McDonald says he anticipates a lag of about three years before the sensors and antennas will be produced in quantity and put to practical use. Among the potential customers, he says, will be technology-oriented federal agencies such as NASA and the Defense Department. Other future users could be in the health sciences field.

Meanwhile, private companies are doing their own research. “What technologists have been doing for years is advancing long-wavelength technology to shorter and shorter wavelengths. The frontier of that is infrared,” says McDonald.

“All we can do is present the possibilities. The commercial world decides what’s viable.”