||Recently, the concept of MIMO communications has created considerable attention both in mobile communications and advanced radar technology. In MIMO radar technology, the antenna should be capable of operating in wideband and high gain. In this thesis, we design a C-Band MIMO antenna for MIMO radar applications by introducing reaction theorem to enhance wideband isolation, and adding superstrates with special designs to improve gain enhancement. |
First, we propose coplanar waveguide (CPW) to feed multi-input multi-output (MIMO) antenna. We choose CPW feeding because it provides the advantage of wideband impedance matching. Our antenna structure is similar to protruding structure, which provides isolation enhancement. In order to further improve the isolation over the desired frequency band, the reaction theorem is applied. By introducing equivalent magnetic current, the induced voltage can be suppressed. So that wideband MIMO antenna design can be done.
In order to enhance the gain over C-band, three stacked superstrates are proposed. By analyzing the electric field on the xz, yz plane of the antenna, we create a metal strip on the corresponding location on the superstrate to enhance gain. Compared with common superstrate, three stacked superstrates are placed only at a distance of 0.25λ, with a gain enhancement of 1~3 dB.