a plurality of receiving circuits, said plurality of receiving circuits being M in number, each of said plurality of receiving circuits configured to adjust at least one of an amplitude and a phase of a received signal and to output an adjusted received signal;

a plurality of antenna elements configured to receive a radio frequency signal, said plurality of antenna elements being N in number, the number N being greater than the number M, said plurality of antenna elements constituting a plurality of sets of partial array antennas, each set of partial array antennas including M antenna elements of said plurality of antenna elements;

an antenna switching circuit configured to connect M antenna elements of said plurality of antenna elements to respective receiving circuits of said plurality of receiving circuits;

a combiner configured to combine M adjusted received signals outputted from respective receiving circuits of said plurality of receiving circuits into a combined received signal;

a signal quality determination circuit configured to determine signal quality including a CNR (Carrier to Noise Ratio) of the combined received signal; and

a controller configured to control said antenna switching circuit, configured to adaptively control said plurality of receiving circuits so as to form a radiation pattern with a beam in a direction of a desired wave and nulls in directions of interference waves, and configured to cause said antenna switching circuit to connect M antenna elements of said plurality of antenna elements included in one set of partial array antennas of said plurality of sets of partial array antennas to respective receiving circuits of said plurality of receiving circuits,

wherein said plurality of antenna elements is disposed so that for any first set of partial array antennas of said plurality of sets of partial array antennas, and for any second set of partial array antennas of said plurality of sets of partial array antennas different from said first set of partial array antennas, there is a first line defined by feeding points of two antenna elements of said first set of partial array antennas and a second line defined by feeding points of two antenna elements of said second set of partial array antennas such that the first line and the second line are not parallel,

wherein said controller is further configured to cause, when the CNR is equal to or larger than a predetermined threshold value, a signal from one receiving circuit of said plurality of receiving circuits to be outputted directly to said signal quality determination circuit, and the adjusted received signals from other receiving circuits of said plurality of receiving circuits to be attenuated, and

wherein said controller is further configured to control said antenna switching circuit, when the CNR is smaller than the predetermined threshold value and based on signal strengths of the adjusted received signals, to connect M antenna elements of said plurality of antenna elements included in one set of partial array antennas of said plurality of sets of partial array antennas to respective receiving circuits of said plurality of receiving circuits so as to improve the signal quality.