By John Keller
MORGANTOWN, W.Va. - University researchers, working with U.S. Navy and industry funding, have developed a new way to capture RF signals that proponents claim can replace a 16-foot monopole or dipole antenna with a 2-inch doughnut-shaped device.
The latest work on the new antenna involves imprinting its design on tiny printed circuit boards to embed in small high-frequency devices such as global positioning system (GPS) receivers.
Developers call it the Contrawound Toroidal Helical Antenna, which consists of at least two helices wrapped around a doughnut-shaped core and fed from opposite directions. The idea came from James Smith, director and professor for the Center for Industrial Research Applications at West Virginia University in Morgantown, W.Va.
Research funding is coming from the Naval Surface Warfare Center activity at Dam Neck Atlantic Fleet Combat Training Center in Virginia Beach, Va., and from venture capitalist Integral Technologies Inc. of Vancouver, British Columbia.
"We believe that for the world it will make an incredible impact on wireless communications," says William Robinson, president of Integral Technologies. "We are about 300 percent better than the average antenna - or 300 percent smaller."
While many antennas have directional characteristics and must be installed on stable platforms and pointed toward signals of interest to be most effective, this new antenna emits and receives with equal proficiency from virtually all angles and directions.
"It is almost perfectly isotropic in nature, and almost spherical all around," Robinson says. "It emits as well at the bottom, middle, or sides, and puts out a signal over 360 degrees."
U.S. Navy officials are particularly interested in the antenna for shipboard and covert applications, proponents say.
"It is pretty consistent over its sphere of influence, and has unique characteristics when in close proximity of other antennas and metal bodies," Smith says. "It will be particularly useful for things that move a lot, such as vehicles and ships in heavy waves. We don`t have trouble with fade in and fade out."
Smith predicts the antenna will also be attractive for covert operations that call for small, undetectable antennas, and on ships, vehicles, aircraft, and fixed sites that must defend against hostile attack.
Several of today`s so-called "smart" munitions seek and attack traditional antenna shapes to disrupt communications and sensors, Smith points out. These munitions could be rendered ineffective - at least for a while - if platforms were to use the unconventionally shaped Contrawound Toroidal Helical Antenna.
Still, perhaps the most attractive aspect of the new antenna is its small size. Robinson gives the example of a military satellite dish antenna that is 2.5 feet in diameter, which must acquire and lock onto satellite signals before sending and receiving.
"Our antenna replaces that dish with a 6-inch- diameter round dowel with copper wire wrapped around it that locks onto six satellites simultaneously," he says. The new antenna also does not need to be pointed at satellites to be effective, he says.
"Now four of our antennas can fit on a postage stamp," Robinson continues. "Soon they will be in GPS receivers in watches. We have managed to create our first antenna on a silicon chip that is one-sixteenth of an inch thick that can lock into 6 satellites for GPS positioning.
Robinson says engineers can build the new antennas "anywhere from the size of a pencil eraser, to the size of a car, and all sizes in-between," depending on the frequency bands of interest.
Researchers have built antennas of the new design to receive signals from below 1 MHz to above 1 GHz, Smith says.
