Bandwidth enhancement of multislot antenna fed by microstrip line

An improved wideband multislot antenna for broadband wireless applications is proposed and experimentally studied. The proposed antenna is composed of three different narrow slots and fed by a microstrip line terminated with a wide open-circuit stub. By using the combination of multislot and patch-like tuning stub, the antenna's impedance bandwidth is enhanced significantly while keeping good polarization purity within a much wider bandwidth. The antenna is studied both numerically and experimentally. It is shown that the bandwidth of the antenna is from 5.1 to 13.1 GHz, which is about 88% (for reflection coefficient vertical bar S-11 vertical bar lower than -10 dB). Relatively stable radiation pattern having cross-polarization level lower than 19 dB and gain flatness of 3 dB can be achieved within the antenna's bandwidth. Owing to its wideband characteristic, it is a promising candidate for broadband communication or identification systems.