On the Envelope Correlation Coefficient of an LTE Reference Antenna System for Band 13

Abstract

This document presents the investigations on two coupled reference antennas for LTE Band 13 (uplink 777MHz to 787MHz, downlink 746MHz to 756MHz). An important figure of merit to quantify coupling effects in multiple input multiple output (MIMO) antenna systems is the envelope correlation coefficient (ECC). The single antenna element is presented with radiation pattern and scattering parameters. It is a planar device, easy to be etched or milled as dimensions are given. The ECC investigations were done by measurement and simulation, the results are presented and compared. A good agreement between the simulated and the measured ECC can be recognized. In wireless data transmission the use of Multiple Input Multiple Output (MIMO) antenna technology introduces yet another degree of freedom and vastly rises the reachable data throughput. Transmission systems take advantage of the several different propagation paths. They send different data streams through multiple antennas on different paths through the wireless channels. Receivers pick up the mixed data streams. By orthogonalization in the receiver these paths can be treated as separated ones. The less the received data are correlated, the higher is the performance of the transmission system. Simply spoken, unnecessary introduction of data correlation has to be avoided in all stages of the transmission. Looking at small sized hand held user equipment (UE) it is likely that antennas are closely spaced to each other. This proximity introduces unwanted coupling effects and in this way correlation, which results in a performance degradation. (1)-(15) perform similar investigations, but deal with antennas for other purposes. This paper shows an investigation of the ECC on an antenna setup with two coupled dipoles for LTE band 13.