Description
The Array Radiometer Core Demonstrator, ARCD, project is the development of receiver electronics for four 12 GHz spectrometer channels at 340GHz Cf. The development included LO multiplier chain, mixer, horn, IF system, BE and test set-up.
The target instrument for the radiometer core is the STEAMR instrument (Stratosphere Troposphere Exchange And Climate Monitor Radiometer). The system basically consists of an array of 14 heterodyne receivers based on broad band sub-harmonically pumped planar Schottky diode mixers operating in the 320-360 GHz spectral range. The signal originating from both sidebands is down-converted to an intermediate frequency (IF) in the range 3.6-15.6 GHz. The IF signal is filtered, amplified and spectrally resolved using autocorrelation spectrometers that provide a maximum instantaneous bandwidth of 12 GHz with a baseline spectral resolution of 25 MHz.
The tests show that the ARCD is a fully functional 512 channel spectral radiometer. The design allow for four receivers simultaneously to operate and to forward data to the control system, in this case a PC. System noise temperature is below 1000 K for the low (3.6-9.6 GHz) and below 2000K for the high (9.6-15.6 GHz) IF frequency band. System stability by means of Allan variance is approximately 10s.
