Abstract: A system for counteracting antenna movement in a directional antenna, including a feed horn for providing an electromagnetic signal, a sub-reflector for controlling a direction of reflection of the electromagnetic signal provided by the feed horn, and a main reflector for reflecting the electromagnetic signal arriving from the sub-reflector and transmitting the electromagnetic signal reflected from the main reflector, wherein the sub-reflector includes a metasurface controllable to alter the direction of reflection of the electromagnetic signal by coordinated changes of phase over the sub-reflector surface. A sub-reflector for an antenna, the sub-reflector including a metasurface, wherein the metasurface is controllable to alter a direction of reflection of an electromagnetic signal by coordinated changes of phase over the sub-reflector surface. Related apparatus and methods are also described.

Abstract: The present invention describes a device and a method for grading diamonds using electromagnetic fields with a radiofrequency or terahertz frequency. The method for grading diamonds comprises placing the diamond (4) into a grading device, applying an electromagnetic field with a frequency range of up to 30 THz to the diamond, recording a modulated signal received from the diamond in a form of S-parameters as a function of frequency or any other parameter that can be deduced by applying said electromagnetic field, processing the recorded signal in the processing unit to obtain data containing information about either an amplitude, or phase, or both of the recorded S-parameters as a function of frequency or said any other parameter, performing calculations relating to the obtained data, and running a computer algorithm correlating the calculated data to either nitrogen concentration, boron concentration or plastic deformation in diamonds, thereby allowing grading of the diamond.

Abstract: The present invention describes a device and a method for grading diamonds using electromagnetic fields with a radiofrequency or terahertz frequency. The method for grading diamonds comprises placing the diamond (4) into a grading device, applying an electromagnetic field with a frequency range of up to 30 THz to the diamond, recording a modulated signal received from the diamond in a form of S-parameters as a function of frequency or any other parameter that can be deduced by applying said electromagnetic field, processing the recorded signal in the processing unit to obtain data containing information about either an amplitude, or phase, or both of the recorded S-parameters as a function of frequency or said any other parameter, performing calculations relating to the obtained data, and running a computer algorithm correlating the calculated data to either nitrogen concentration, boron concentration or plastic deformation in diamonds, thereby allowing grading of the diamond.