3.1. Radiometer Fundamentals

Publisher Summary This chapter discusses the basic concepts related to radiometers. In a radiometer system, the purpose of the receiver is to select and amplify the signal received by the antenna and to provide an output signal to a chart, digital recorder, or other display/processing unit. The accurate reproduction of the amplitude and spectral characteristics of the input signal is of prime importance. The receiver must be linear in output even when it operates over a large dynamic range of amplitude and should introduce a minimum of noise to the signal being amplified. Typical power gains of receiver systems are 120 dB. Bandwidths used in observations vary in width from a few kilohertz up to a few gigahertz. The chapter discusses the contributions to total system temperature for several operational radiometer systems. Factors to be applied for several representative types of input bandpasses and output filters used in radiometer systems are given. The basic receiver system, single-sideband systems, and double-sideband systems are discussed and the Dicke modulated receiver system is also elaborated.

[1]  M. Ryle,et al.  An investigation of radio-frequency radiation from the sun , 1948, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[2]  J. Edrich.  A Coolable Degenerate Parametric Amplifier for Millimeter Waves (Letters) , 1974 .

[3]  D. Staelin,et al.  THREE PULSARS WITH MARCHING SUBPULSES. , 1970 .

[4]  R. Wilson,et al.  Detection of Millimeter Emission Lines from Interstellar Methyl Cyanide , 1971 .

[5]  Marshall H. Cohen,et al.  Radio Astronomy Polarization Measurements , 1958, Proceedings of the IRE.

[6]  V. Radhakrishnan,et al.  ON THE MEASUREMENT OF POLARIZATION DISTRIBUTIONS OVER RADIO SOURCES , 1964 .

[7]  J. Taylor,et al.  OBSERVATIONS OF RAPID FLUCTUATIONS OF INTENSITY AND PHASE IN PULSAR EMISSIONS. , 1971 .

[8]  G. Moorey,et al.  A 1024−channel digital correlator , 1975 .

[9]  E. Kollberg,et al.  Rutile Traveling-Wave Maser System for the Onsala 84-Foot Radio Telescope (Correspondence) , 1968 .

[10]  A. Tsuchiya,et al.  A Time-Sharing Polarimeter at 200 MC , 1958, Proceedings of the IRE.

[11]  R. Dicke.  The measurement of thermal radiation at microwave frequencies. , 1946, The Review of scientific instruments.

[13]  An up-converter solar radiospectrograph for the frequency range 200-2000 Mc/s , 1966 .

[14]  G. Aitken,et al.  A new correlation radiometer , 1968 .

[15]  W. W. Snell,et al.  A radiometer for a space communications receiver , 1963 .

[16]  S. Petty,et al.  X-band traveling wave maser (Correspondence) , 1968 .

[17]  J. Hunton,et al.  Microwave Variable Attenuators and Modulators Using PIN Diodes , 1962 .

[18]  H. Nyquist.  Thermal Agitation of Electric Charge in Conductors , 1928 .

[19]  Radio interferometers of intermediate type , 1968 .

[20]  J. Edrich,et al.  A parametric amplifier for 46 GHz , 1971 .

[21]  K. Wesseling.  A single-sideband, double-sideband interferometer receiver for radio astronomy , 1967 .

[22]  R. Manchester.  OBSERVATIONS OF PULSAR POLARIZATION AT 410 AND 1665 MHz. , 1971 .

[23]  J. Whiteoak,et al.  Polarization of 20-cm Wavelength Radiation From Radio Sources , 1962 .

[24]  W. Selove.  A DC Comparison Radiometer , 1954 .

[25]  M. Cohen.  The Cornell Radio Polarimeter , 1958, Proceedings of the IRE.