Optimization of a Multi-port Amplifier Using a Least Squares Evolutionary Relaxation Method
A satellite designed for mobile telecommunications applications may contain a large aperture reflector fed by an array at its principle focus. Each radiator element of the array has a one-to-one correspondence with a spot on the earth, so that radiation patterns are pointed at different locations on the Earth by different combinations of elements. Before the signals arrive at the array with their specified complex weights they must undergo amplification. This can be provided by a beam forming network composed of between 10 and 20 multiport amplifiers (MPA). The object of this paper is to describe an optimization method that will improve the performance of the beam forming network
MODELLING OF A MULTIPORT AMPLIFIER FOR A MOBILE COMMUNICATIONS SATELLITE
Some communication satellites have an antenna that consists of a fixed parabolic reflector that is fed by an array. Such antenna systems can be programmed to produce a variety of fixed beams in response to traffic demands and can be built so that each array element is fed by its own high power amplifier. However benefits can accrue if the amplifiers are incorporated into Multiport Power Amplifiers (MPAs). Ideally all the MPA inputs are divided equally between all amplifiers and there is a one to one correspondence between the MPA feed ports and the MPA array ports. Due to imperfections in the INET and the ONET, and differences between the amplifiers, the ideal behaviour is never realized in practice. To optimize the performance of any manufactured MPA a deliberate offset in the gain and phase shift of each amplifier has to be introduced to compensate for the imperfections introduced by the INET, the ONET and their associated cabling. This paper shows how the RF modelling of an MPA has been performed by computer modelling using HFSS, Matlab and the Agilent ADS software.
Energy
Energy is often defined as the ability to do work. There are many forms of energy. A few examples include; Gravitational energy, Kinetic energy (energy of motion), Thermal energy (heat energy), Potential energy. Potential energy is the energy something has based on its position in the universe. A stretched elastic band has potential energy. A rock held up in the air has potential energy based on its position.