Abstract: Provided is a method of calibrating a microwave radiometer, which eliminates use of liquid nitrogen as a calibration source. The method is applied to a microwave radiometer configured to receive, by a receiver having a primary radiator connected thereto, a radio wave emitted from an object to be measured depending on a temperature of the object to be measured and to measure a brightness temperature of the object to be measured from an output signal of the receiver. In the method, the method a noise temperature Trx of the receiver appearing on an output side of the receiver is calibrated by observing a plurality of calibration sources having known brightness temperatures. The method includes using a radio wave reflector configured to totally reflect noise radiated from an input side of the receiver as one of the plurality of calibration sources.

Abstract: Provided is a method of calibrating a microwave radiometer, which eliminates use of liquid nitrogen as a calibration source. The method is applied to a microwave radiometer configured to receive, by a receiver having a primary radiator connected thereto, a radio wave emitted from an object to be measured depending on a temperature of the object to be measured and to measure a brightness temperature of the object to be measured from an output signal of the receiver. In the method, the method a noise temperature Trx of the receiver appearing on an output side of the receiver is calibrated by observing a plurality of calibration sources having known brightness temperatures. The method includes using a radio wave reflector configured to totally reflect noise radiated from an input side of the receiver as one of the plurality of calibration sources.

Abstract: A process for producing graphite includes heat treating, in an inert gas or in vacuo, at least one polymer selected from the group consisting of a polyphenyleneoxadiazole, polybenzothiazoles, a polybenzobisthiazole, a polybenzoxazole, a polybenzobisoxazole and a polythiazole, at a temperature of at least 1600.degree. C., preferably at least 2000.degree. C., for at least 30 minutes, preferably at least 60 minutes, to convert the polymer to a highly-graphitized graphite. The process produces almost perfect graphite in any shape, such as film-shaped for large-area graphite, fibrous or powdered.