A Novel 183GHz Subharmonic Schottky Diode Mixer
Abstract
The technique of microwave .
limb sounding -from space
represents a very powerful tool for determining the atmospheric
processes involved in ozone depletion, the greenhouse effect, acid
rain, etc.. Unfortunately, the technology involved in producing
millimetric and submillimetric devices is highly complex, and
miniature. The power levels and environmental conditions
existing aboard spacecraft in present 'use, 5 differ from those
required by the low noise heterodyne receivers employed by the
Radio Astronomy community. Therefore, great effort has been
spent in the design of radiometers with limited power and weight
requirements, so that they can withstand the rigours of launch
and operation in space.
This thesis describes the design and construction of a
subharmonically pumped, double diode mixer which is now used
in an airborne atmospheric radiometer. The mixer power
requirement and rugged nature make it an ideal option for space
operation. The assembly of the millimetric circuit required the
development, of novel techniques which enabled the incorporation
of discrete circuit elements onto a single quartz substrate. This
allowed the physical testing of the millimetric circuit
independently of the RF block.
A detailed investigation into the `whiskering' technique was
carried out. It was thus possible to pinpoint errors that had
previously occurred in assembly and which had resulted in the
failure of a space flight device. With the adoption of quantified
procedures, devices constructed using the `whiskering' technique
were shown to be considerably more resilient than had previously
been thought.
The performance of the mixer is comparable with other
designs using Schottky diodes at room temperature (-1200K DSB)
and the local oscillator power requirement is easily met with a
single solid state source.
A simple theoretical analysis using the Seigel and Kerr
program was undertaken in conjunction with RF measurements
performed on a 65X scale model to determine steps required for
further improvement.
Authors
Mann, Christopher MarkCollections
- Theses [3930]