Novel Dual Band Resonant Cylindrical Hat-Covered Monopole for Personal Communications

A cylindrical hat-loaded method is employed to make monopoles behave as dual band resonators. The two frequency bands are obtained by perturbing higher propagation modes by modifying the hat length. The longer the cylindrical hat is, the lower the resonant frequencies are obtained. The hat length behaves as an inductive load, also increasing the electric length of the monopole. As a result, a compact resonant structure is got, working at two different frequencies without modifying the omnidirectional radiation pattern at both bands.