Patent attributes
A microwave prism is used to repoint an operational Direct-to-Home (DTH) or Very Small Aperture Terminal (VSAT) reflector antenna as part of a ground terminal to receive (or transmit) signals from a different satellite or orbital position without physically moving the reflector or the feed horn antenna. The microwave prism operates by shifting the radiated fields from the horn antenna generally perpendicular to the focal axis of the parabolic reflector in order to cause the main beam of the reflector to scan in response. For an existing reflector antenna receiving signals from an incumbent satellite, a prism has been designed to be snapped into place over the feed horn and shift the fields laterally by a calibrated distance. The structure of the prism is designed to be positioned and oriented correctly without the use of skilled labor. This system allows a satellite service provider to repoint their subscribers to a new satellite by shipping a self-install kit of the prism that is pre-configured to have the correct orientation and position on the feed antenna to correctly re-point the beam at a different satellite once the prism is applied. One benefit of the system is that unskilled labor, i.e., the subscribers themselves, can be used to repoint a large number of subscriber antennas in a satellite network rather than requiring the cost of a truck roll and a technician to visit every site. The microwave prisms to implement this functionality can be constructed in different ways, with homogeneous slabs or blocks, Gradient-Index (GRIN), multi-layered dielectric, geometric or graded-index Fresnel-zone, metasurface, or metamaterial prisms. The geometric and electrical constraints of the design are determined by the incumbent and target satellites and the ground terminal location.
