Analysis and Design of Compact High-Isolation Multi-Port Diversity Antenna

A compact high-isolation multi-port diversity antenna is presented in this paper. The design is a combination of a compact tripolarized antenna and four dipoles etched at four corners of the same ground plane. The feeding configuration is first analyzed to clarify the condition for high isolation of the tripolarized antenna. In the next step, the pattern and polarization orthogonality principle will be applied to add more ports into the antenna structure, allowing the design of a multi-port antenna with isolation better than 22 dB. The proposed multi-port antenna provides an overlapped operation bandwidth of 2.39 - 2.52 (5.3%) while still retaining a compact size and low profile with an overall dimension of (0.8 × 0.8 × 0.1) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda_{L}^{3}$</tex> where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda_{L}$</tex> is the free-space wavelength at the lowest operating frequency.