Abstract: A high frequency radiation transceiver is presented. The transceiver includes an electrodes' arrangement, including two or more electrodes, where two of said electrodes are accommodated in a spaced-apart relationship defining a cavity for free space propagation of electrons between them. One of said two electrodes is configured to be responsive to an external input optical signal to emit an electron flux towards the other electrode. Said two or more electrodes are configured to define first and second electrode portions, the first portion having at least a region thereof exposed to said electron flux and operable as an antenna feeding port causing an electric current in said second portion and the second portion being configured and operable as an antenna radiating portion.