A Compact Triple-Band Circularly Polarized Slot Antenna for MIMO System

This paper presents a compact triple-band circularly polarized two-port antenna for multiple-input multiple-output (MIMO) applications. The proposed antenna is designed by using simple stub geometry, multi-slit, and multi-slot techniques. In order to realize the proposed CP antenna, one stub has been embedded in the feed-line. By embedding stub in the feed-line and removing two slits from the ground plane, the S-parameters and axial ratio bandwidths have been noticeably increased. The MIMO antenna has a low-profile geometry and a dimension of 16 × 16 × 0.82 mm3. As a result, the three notched bands are good in existing interference bands of C-band (6.21 – 6.63 GHz), lower Ku-band (12.1−13.01 GHz), and lower K-band (18.24−21.01 GHz). In addition, the axial ratio bandwidth over the resonating bands are 3.79% (6.27 − 6.53 GHz), 24.20% (10.44 − 13.30 GHz), and 3.81% (18.81 − 19.54 GHz), respectively. The proposed MIMO antenna has a stable radiation pattern, sufficient gain, and low envelop correlation coefficient (ECC < 0.02) over the resonating bands, which is suitable for MIMO system applications.