Electrically switchable multiport matching network for 2-Port MIMO antennas

Typically, symmetric 2-port Multiple Input - Multiple Output (MIMO) antennas for LTE-enabled small mobile wireless devices feature radiation modes with significantly different radiation quality factors. Due to the high modal radiation quality factors it is difficult to match both radiation modes over the desired broad frequency range. In order to solve this problem, a solution for electrical switching between different frequency bands is of interest. The solution, reported in the present paper, uses electrically switchable multiport matching network. The differential mode is switched between two frequency bands by means of a single high performance RF-PIN diode while the common mode is matched over a broad frequency range. Overall, the electrically switchable multiport matching network realizes high total multiport return loss for both switching states.