Mutual coupling investigation between loop and two inverted-L antennas operating below 1 GHz

To overcome antenna design challenges posed by the increasing number of frequency bands, the use of separate transmit (Tx) and receive (Rx) narrow-band antennas is proposed. In addition, a second Rx antenna is utilised for multiple input-multiple output (MIMO) application. While sufficiently low coupling between two antennas is important so as to gain the benefits of MIMO, this becomes even more challenging when considering coupling between three antennas. In this reported work, this is addressed by utilising a loop antenna as one of the three antennas, where the other two will be conventional inverted-L antennas. The measurements show that low coupling is possible between all three antennas, while having low correlation between the two Rx antennas.