Highly Isolated Compact Planar Dual-Band Antenna With Polarization/Pattern Diversity Characteristics for MIMO Terminals

A highly isolated two-element dual-band antenna with polarization/pattern diversity is presented in this letter for multiple-input–multiple-output (MIMO) terminals. The MIMO configuration consists of two orthogonally placed identical monopole antenna elements. In both the bands (2.3–2.5 and 5–5.2 GHz), isolation (|
S
₂₁
| or |
S
₁₂
|) ≥ 20 dB is achieved by using a simple decoupling structure. Measured impedance bandwidth of 200 and 190 MHz is achieved in the lower and upper bands, respectively. The individual antenna element has a size of 14 mm × 14 mm, and the MIMO configuration of two elements covers an area of 38 mm × 18.2  mm. Polarization diversity between the elements is achieved by placing them orthogonal to each other, whereas pattern diversity is verified through measurement of the envelope correlation coefficient and radiation patterns. The elements exhibit good efficiency and gain in spite of being compact. The measured and simulated results verify that the proposed design performs well in both the bands.