Integration of coupling resonator as port-isolator and MMLC-Minkowiski fractal loop for Wi-Max rejection in 4-port compact UWB MIMO antenna

摘要

This paper presents a 4-port compact UWB MIMO antenna. It has 45 degrees tilted offset feed for better impedance matching and connected to cornered cut-out quad-radiators. Radially symmetric resonators are provided for impedance matching and isolation improvements. A miniaturized magnetic LC (MMLC) Minkowiski fractal loop acts as a magnetic shield between electric walls of feed and resonator for Wi-max band rejection. The contra-rotational symmetry of resonator and rotationally asymmetric strips in ground enhances isolation. To validate, a prototype antenna is fabricated and measured which shows good agreements. The proposed antenna has a compact dimension 31 mm x 31 mm, operates from 2.27 to 11.7 GHz and reject bands at 3.0-4.2 GHz. The average gain is > 4 dBi with ECC < 0.16 in the operating band. An equivalent circuit topology is also modelled which validates the design. The multi-port antenna system can be used for microwave imaging, RF-sensing and radar applications.