Frequency coverage for weather and science missions in mm-wave and submm-wave radiometers is increasing and it is now possible for Omnisys to commercially offer receivers up to 1-2 THz. For frequencies exceeding 300 GHz, integrated MMIC technology is preferred as it enables performance improvements and allows for more efficient system level implementations.

A record low optimum receiver noise of 1100 K and 2200 K DSB was measured at 325 GHz and 650 GHz centre frequency, over 0.8 – 15 GHz RF bandwidth. The minimum receiver noise temperatures were measured at 700 K for the 325 GHz receiver and 1250 K for the 650 GHz receiver. The receiver short-term stability was measured in normal lab environment without applying any thermal regulation or EMI shielding reaching Allan times in the order of 7 - 15 seconds. The cross-polarisation discrimination XPD was measured to be better than -25 dB over the entire RF band for the 325 GHz receiver and better than -20 dB for the 650 GHz receiver. Antenna far-field measurements and simulations at 325 GHz were in excellent agreement and at around -30 dB level while the FWHM of the 650 GHz was matching the simulation at 8°, but limitations in the measurement set-up did not permit to accurately characterise the far-field pattern.