A NEW CONCEPT FOR IMPROVING THE PERFORMANCE OF ELECTRICALLY SMALL ANTENNAS

Using advances in the areas of multi-mode, closely coupled miniaturized radiators and artificially engineered materials, ultra-broadband, highly efficient, electrically small antennas were developed for operation in military communications systems. A low-profile UWB antenna was developed that is composed of two electrically small loops coupled together in their near fields. Each loop has a three-dimensional surface with a bent diamond-arm shape. Half of each loop placed on top of an infinite conducting ground plane is used in the design. Each loop is loaded with a top hat to reduce the lowest frequency of operation of the antenna.

The antenna radiates like a vertically polarized monopole with omnidirectional, vertically polarized radiation patterns in the azimuth plane. The antenna demonstrates consistent radiation characteristics over a 4:1 frequency band. At its lowest frequency of operation, the antenna has an extremely low height of 0.033 λ_min, where λ_min is the free-space wavelength at the lowest frequency of operation of the antenna. Moreover, the antenna has lateral dimensions of 0.22 λ_min × 0.22 λ_min at the lowest frequency of operation.