Compact UWB MIMO Vivaldi Antenna With Dual Band-Notched Characteristics

A novel ultra-wideband (UWB) multiple-input multiple-output (MIMO) Vivaldi antenna with dual band-notched characteristics is presented and fabricated. The antenna is comprised of an improved ground plane and two microstrip feeding lines with a compact size of $26\times 26$ mm2. The evolutionary process of the antenna is given. By etching the T-shaped slot on the ground plane, the port isolation between individual antenna elements can be greatly increased. Meanwhile, by adding two split ring resonator (SRR) of different sizes next to the microstrip feed lines, dual notches can be achieved to filter the interfere of WLAN and X-band communication satellites. The notched mechanism is analyzed from the surface current distributions. The experimental results show that the impedance bandwidth of the designed MIMO antenna is from 2.9 to 11.6 GHz, along with two notched bands covering 5.3–5.8 GHz and 7.85–8.55 GHz, and the mutual coupling is less than −16 dB in the whole working bandwidth. The MIMO antenna has good radiation characteristics, stable gain, and very low envelop correlation coefficient (ECC <0.02), which is suitable for UWB MIMO system applications. The idea in this paper also has a certain guiding significance for the study of band-notched MIMO Vivaldi antenna.