The polarization rotator is disposed in the forward and reverse propagation paths of the CGI light between the viewing region and the end reflector.

The memory device includes a pipelined buffer with selectable propagation paths to route data from the input connection to the output connection.

The transmission weight and interference coefficient of the obtained propagation path matrix is calculated by a transmission weight / interference coefficient calculating unit (24).

The adjustment of said phase shifts brings about a systematic fluctuation of at least one transmitting direction of the antenna during the transmission of the radio signal, so as to provide diversity of propagation paths.

Provided is a radio communication device which can separate propagation paths of antenna ports and improve a channel estimation accuracy even when using virtual antennas.

WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions.

Since the significances of propagation paths are different from each other according to the magnitude of average reception power, efficient transmissions can be performed in accordance with the significances.

Propagation paths for the third and fourth output lights comprise widths that cause a prescribed optical path length difference to occur between the third and fourth output lights.

Light emitters (2) and light detectors are optically coupled to the panel (1) to define a grid of light propagation paths inside the panel (1) between pairs of light emitters (2) and light detectors.