A New Compact Wideband MIMO Antenna—The Double-Sided Tapered Self-Grounded Monopole Array

Abstract

We present a new compact wideband multiple input multiple output (MIMO) antenna—the double-sided 4-port arm-tapered self-grounded monopole array, briefly referred to as the butterfly antenna, in the communication. The antenna is very compact with low correlation between ports and high diversity gain. The genetic algorithm optimization scheme has been employed in the design. Simulation results have been verified against measurements. The measured reflection coefficients at all ports are below <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex> </formula> 7 dB over 0.5–9 GHz and below <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$-$</tex></formula> 4.5 dB over 0.4–0.5 GHz and 9–15 GHz. The measured correlation coefficients are below 0.4 over 0.4–15 GHz and lower than 0.1 in most of the frequency band. This new MIMO antenna is developed as a transmit antenna in reverberation chambers, and we believe that it will find more applications in other systems, such as micro base station antennas in wireless communication systems.