A Maser Amplifier for Radio Astronomy at X-Band

The design and operating characteristics of a maser radiometer for use in radio astronomy at 3-cm wavelength are discussed. The operating system which is described has a bandwidth of 5.5 mc and an input noise temperature, including background radiation into the antenna, of about 85°K. An rms fluctuation level of about 0.04°K is attained using an averaging time of 5 seconds. A discussion of the factors determining the sensitivity of such devices is presented.