Computationally Optimized MIMO Antenna with Improved Isolation and Extended Bandwidth for UWB Applications

摘要

Isolation and bandwidth are the two important performance parameters of the multiple-input-multiple-output (MIMO) antenna.A small footprint of an antenna with enhanced isolation and extended bandwidth is highly desirable for space-limited UWBapplications. In this paper, we present a compact and computationally optimized MIMO antenna for UWB applications.The proposed antenna consists of two micro-strip-fed semicircular radiating elements. The inverted prism-shaped groundstub is used to enhance isolation. A truncated-shaped partial ground plane with two ground slots is used for impedancematching over the extended UWB. The circular monopole radiating elements of the reference antenna (RA) are convertedinto semicircular radiating elements for efficient utilization of the available space. The initial design parameters are obtainedfrom the RA. In the next step, the initial design parameters are optimized by a fast and accurate surrogate-assisted optimizationmodel. Using the optimized design parameters, the final design of the antenna is simulated using a computer simulation tool.The prototype of the antenna is fabricated on a Roger substrate (substrate height ‘h’ = 0.8 mm) with a dielectric constantof 3. The manufactured prototype with the size of 31×18 mm~2 is experimentally evaluated and validated using vectornetwork analyser and anechoic chamber. The proposed MIMO antenna provides extended ultra-wide impedance bandwidthof 3–25 GHz (fractional bandwidth 157%), enhanced isolation S21≤−27 dB envelope correlation coefficient (ECC0.002),good pattern diversity, and constant group delay. Finally, the obtained results are compared with the existing literature.