Technology for millimetre wave radiometers

Technology for millimetre wave radiometers is discussed. Distinction between coherent and incoherent detection is also addressed. As an example, a detail of the 70 GHz ultra low noise and high stability receivers for the European Space Agency (ESA) Planck Mission is given. These receivers are part of the low frequency instrument (LFI). The LFI receivers will make use of monolithic microwave integrated circuit (MMIC) and the key components are the low-noise amplifiers (LNA). Indium phosphide (InP) technology has been used for manufacturing the HEMT and PIN diode MMICs. Recently complete elegant breadboard model (EBB) of LFI 70 GHz receivers have demonstrated a 30 K noise temperature with 16 GHz bandwidth and a 1/f knee frequency of 30 MHz. Described radiometer modules form flexible basis for constructing radiometers with many pixels for millimetre wave imaging and remote sensing applications.