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
On the optimisation of distributed ambiguity ratio and directivity for a synthetic aperture radar
Space borne Synthetic Aperture Radar (SAR) is a radar capable of high resolution imaging of the surface of the earth. Typical applications of a space borne SAR include the observation of oil slicks, ice packs, shipping lanes, industrial pollution and agricultural usage. The SAR spacecraft travels in a low earth orbit focusing a narrow radiation pattern upon the earth in the direction along the plane of travel and a wide beam in a plane transverse to this. Whereas the narrow along track or azimuth beam is fixed normal to the spacecraft, the wide elevation beam must have the ability to scan over the surface of the earth. The objective of this paper is to describe a new method of determining the array excitations that form this wide elevation beam taking account of both the antenna and the radar system characteristics.
Evaluation of antioxidants by a rapid polarographic method
A simple, rapid, precise, and reproducible method and an adaptable apparatus for polarographic measurement of lipid peroxidation and antioxidant activity is described. This method measures antioxidant activity within a few min time as compared to the hours or days needed for several widely used methods. Peroxidation rates were measured for different lipids as a function of amount of lipid, and amount of biocatalyst. The method is applicable to the detection and measurement of the antioxidant effects exhibited by weak antioxidants and has been satisfactorily used for the measurement of the antioxidant activity of different concentrations of powerful antioxidants.