Millimeter-Wave Atmospheric Temperature and Humidity Sensors
NASA Jet Propulsion Lab Collaboration

There is a basic, long-term need for millimeter-wave radiometers in Earth orbiting systems which monitor atmospheric parameters such as temperature, humidity, ozone concentration, and other chemical constituents. Future NASA/JPL missions such as ATMS, C/MIS, and AMLS will all require sensors of this type. By realizing these sensors with Monolithic Millimeter-Wave Integrated Circuits (MMICs), it is possible to achieve an order of magnitude reduction in mass, volume, and cost in large quantities over other implementations. This enables a focal plane array of receivers to be built, capable of contiguous imaging of Earth's atmosphere in these frequency bands.The goal of the IIP program at JPL is the maturation of MMIC-sensor technology for use at lower-risk in future rapid-paced flight programs. Research efforts at Caltech have contributed to the development of two prototype multi-chip receiver modules in the 100-140 GHz and 170-210 GHz bands. One example is the broadband, balanced mixer in the 100-140 GHz module. This chip was designed at Caltech, and fabricated at TRW using a standard monolithic InP-HEMT process. It has conversion loss of 15 2 dB from 100-130 GHz with 5 dBm LO drive at 80 GHz. Measurements also indicate a wide IF bandwidth extending beyond 50 GHz. This is the first monolithic HEMT diode balanced mixer demonstrated in this frequency range.

Interior view of 100-140-GHz Receiver
Millimeter-Wave Receiver ModulesI
Other chips developed at Caltech for this program include the second-harmonic mixer for 170-210 GHz, and a full waveguide band frequency tripler for 75-110 GHz which is needed for LO sources in other modules. In addition to MMIC development, Caltech has participated in the test and integration of these circuits in the multi-chip blocks. The data indicate receiver conversion gains of about 30 dB and noise figure of 6 dB at room temperature over most of the IF bandwidth.
Publications:

A Full Waveguide Band MMIC Tripler for 75-110 GHz , M. Morgan and S. Weinreb -IEEE MTT-S Intl. Microwave Symposium, May 20-25, 2001, Phoenix, AZ.

A Monolithic HEMT Diode Balanced Mixer for 100-140 GHz , M. Morgan and S. Weinreb -IEEE MTT-S Intl. Microwave Symposium, May 20-25, 2001, Phoenix, AZ.


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updated March 1, 2001