Using transient properties of a tunable narrowband antenna to realize a dual-band antenna

Abstract

Switched antennas have been used for wireless communication in order to achieve a direct modulation. A combination of semiconductor switch and a radiating element can be employed to decouple the information bandwidth from the antenna bandwidth. This method allows the system to operate in a wideband range using small and resonant antennas instead of wideband radiators. The first attempt to use a switched antenna to increase the impedance bandwidth was done by Merenda (USA Patent 5402133, March 28, 1995) and there have been several publications afterwards. However, most designs suffer from signal ringing, spurious radiation and high switching rate requirements.