Patent ID: 8190104

Claim:
A MIMO antenna apparatus comprising at least three antenna elements for respectively receiving radio signals, and a demodulator circuit for demodulating radio signals received through at least two of the antenna elements by using a MIMO (Multi-Input Multi-Output) scheme, the apparatus comprising: a detector circuit for detecting received-signal levels of the respective radio signals received by the respective antenna elements; a switch circuit for connecting at least two of the antenna elements to the demodulator circuit; a degree-of-coupling memory for storing, in advance, degrees of electromagnetic coupling among the at least three antenna elements; and a controller for controlling the switch circuit based on the received-signal levels detected by the detector circuit and the degrees of electromagnetic coupling stored in the degree-of-coupling memory, wherein the controller calculates a current transmission capacity based on the received-signal levels detected by the detector circuit; calculates an estimated transmission capacity assuming that at least one of the antenna elements currently connected to the demodulator circuit is changed to a further antenna element not connected to the demodulator circuit, based on the received-signal levels detected by the detector circuit and the degrees of electromagnetic coupling stored in the degree-of-coupling memory; and when the current transmission capacity becomes lower than the estimated transmission capacity, controls the switch circuit to connect the further antenna element to the demodulator circuit.