A reconfigurable antenna based on an ultrawideband to narrowband transformation

This paper presents a frequency reconflgurable printed antenna obtained from the modiflcation of a simple ultrawideband (UWB) design. The initial UWB version is based on a patch with round corners, for smoother current ∞ow, and a microstrip-line feed. The ground plane is partial and rectangular in shape. The used substrate is a Rogers RO3203 board with "r = 3:02 and a height of 1.52mm. A narrowband (NB) antenna is obtained by incorporating a rectangular split-ring slot in the ground plane of the UWB design, below the feed line, and by introducing a narrow gap into its feed line. The ground slot acts as a complementary split-ring resonator (CSRR), which resonates and creates a band notch around its resonance frequency. The feed gap acts as a capacitor, which transforms the CSRR's band rejection behavior to a band pass one. The position of the CSRR split afiects its notch frequency, and consequently the resonance frequency of the NB antenna. Frequency reconflgurability is thus obtained by mounting electronic switches at several locations over the CSRR, and activating one switch at a time, to represent the split. A prototype with two switches is fabricated. The measured re∞ection coe-cient is in accordance with the simulations, which show frequency reconflgurability over two bands. More bands can be made operable by using more switches at optimized locations.