Navy gives URIís small antenna big results
KINGSTON, R.I. -- APRIL 28, 2005 -- The news last June that Rob Vincent, an employee in the Physics Department at the University of Rhode Island, had shrunk the antenna size without shrinking its effectiveness, produced a large group of Doubting Thomases worldwide. Prove it, they demanded.
Vincent and URI, with the help of the Naval Undersea Warfare Center and its antenna test range on Fishers Island, N. Y., have done just that.
On March 31, 14 versions of Vincentís Distributed Load Monopole (DLM) antennas were put through a battery of validation tests. The results exceeded Vincentís and URIís expectations. Smaller is better.
The Navy center responds to a wide variety of military and commercial requests for testing antennas at its Fishers Island over water range, the only such range of its kind in the world. Water provides a better path for transmission and reception than land. The site is located on a low-lying, remote coastal area, free of local interference.
The Fishers Island range is a far-field ground wave antenna test range capable of measuring the performance of antennas ranging in frequency from 2 to 30 megahertz. Gain measurements are done relative to an ideal quarter wave monopole antenna. The URI antennas were tested using the same methods and instrumentation as those used to test and certify Navy antenna systems.
Industry regards such testing as dependable as science permits and often includes the centerís data with products to assure customers of its performance specifications.
Vincentís Plano Spiral Top Hat antenna at 7 megahertz is half the size of a normal quarter-wave antenna operating at that frequency. The URI antenna gain matched the performance of the ideal quarter-wave antenna, and its bandwidth was nearly twice as wide. This type of antenna has multiple uses, including military, marine, amateur radio communications and AM broadcasting.
In addition, the gain of Vincentís capacity Top Hat DLM antenna, which incorporates a helix, a load coil, a capacitive top hat utilizing radial spokes at the top of the antenna and a horizontal plane was nearly identical to the ideal quarter wave antenna. Its bandwidth was greater than 5 percent of the operating frequency and the antenna is more than 70 percent shorter than an ideal quarter wave antenna.
Vincentís standard DLM antennas with a standard helix and load coil were also tested at various frequencies. All exhibited gains nearly equal to the ideal antenna with bandwidths of 3 to 10 percent. The antennas were 33 to 40 percent shorter.
More than 200 businesses, companies, and government agencies have contacted URI seeking information for automotive, marine, and military applications, among others, since the antenna announcement last year. A patent is pending on Vincent's technology. The inventor has made the University of Rhode Island and its Physics Department partners that will benefit from any revenue his invention earns.
URI is close to securing several license agreements. In addition, prototypes have been developed for numerous applications.
To view the test data on URIís antenna technology, go to http://www.uri.edu/news/vincent/report05/ For more information on the Navyís testing facility, go to