US Patent 7113146 Broadband monopole

A broadband monopole is preferably formed as a single arm helical winding formed from copper, aluminum, or other suitable materials. The monopole is embedded in a lossy dielectric material that may include, for example, a potting material and a polyurethane resin or carbon-loaded ceramic shell. In alternate embodiments, the helical winding may be used without the dielectric material, although such an embodiment is not preferred because the input impedance is oscillatory and difficult to match. The resulting antenna operates over an extremely broad band and provides very uniform input impedance.