PORTLAND, Ore. Independent tests appear to support an inventor's claim that his skunk-works antenna design can shrink antenna size by up to 70 percent while maintaining equivalent sensitivity and increasing bandwidth.
The four-part antenna cancels out the normal inductive loading in traditional antenna designs, thereby linearizing the energy radiation along its mast and enabling its diminutive size.
"When we announced my smaller antenna design last year, I got lots of doubting Thomases worldwide. Now, with the help of the Naval Undersea Warfare Center and its antenna test range on Fishers Island, N.Y., we have independent test results to back up our claims," said inventor Rob Vincent, a research engineer in the University of Rhode Island's physics department.
Vincent calls his invention a distributed-load monopole (DLM) antenna. The novel design uses a helix plus a load coil to shrink the size of a normal quarter-wave monopole. According to Vincent, his design can shrink the size of every antenna in use today, from the tiny gigahertz units inside cell phones to giant, kilohertz AM antennas. For instance, a 3-inch-long gigahertz antenna could be shrunk to an inch, and a 300-foot-tall AM band antenna could be reduced to 80 feet high.
In the tests, various DLM antennas from Vincent's portfolio were tested from 7 to 27 MHz. The results indicated that equivalent performance was achieved with antennas 30 to 70 percent shorter than an ideal quarter-wave antenna.
"Basically I am utilizing the distributed capacitance around the antenna to reduce the normally required inductive loading," Vincent said.
Vincent spent almost 30 years at Raytheon Co. and at KVH Industries (Middletown, R.I.), before becoming a research engineer at the University of Rhode Island (Kingston). He began experimenting with antennas there as a skunk-works project.
Vincent chose the Navy's Fishers Island Antenna Complex to test his design because it is located in a low-lying, remote coastal area free from radiation obstructions and man-made electromagnetic interference. The complex offers a 1-mile range over seawater between two sites for testing antennas ranging in frequency from 2 to 30 megahertz. All gain measurements were done relative to an ideal quarter-wave monopole antenna.
Vincent's antenna designs were tested using the official regime the Navy uses to certify its antennas. Vincent's Plano Spiral Top Hat antenna, at 7 MHz, was shown to have equal sensitivity to a normal quarter-wave antenna but at 50 percent the quarter-wave unit's size. In addition, bandwidth of the Vincent design was nearly twice as wide as that of the quarter-wave unit.