Design of Multi-band Small Antenna Based on Single Split-Ring Resonator

To use the single split-ring resonator (SRR) as a basic unit cell for small antenna with multi-band frequency response is proposed. The structure of antenna is consisted of a single spilt-ring resonator and a coupled microstrip line. The designed antenna is numerically optimized with CST Microwave Studio. The radiation properties of the antenna show that there are three frequency bands among which two bands are 1.3?GHz and 2.1?GHz ultra-wideband (UWB), respectively, where S₁₁ is less than -10?dB. The gain at every frequency for the multi-band antenna is above 2.6?dBi, and it increases monotonously with the frequency in the two UWB.