SWEPT HETRODYNE MILLIMETER-WAVE VECTOR NETWORK ANALYZER

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Benchtop wideband vector measurement of millimeter-wave components and networks is desirable for rapid evaluation and evolution of bridge designs in our HF spectrometers. However, no relatively low-cost system of this type presently exists for millimeter-wavelength studies at W-band and higher. Therefore, we have designed a new type of versatile swept vector/magnitude-response evaluation set and contemplate assembling this instrument in a form usable over the millimeter-frequency ranges of our sources at 95, 170, 240 and 250GHz. Our preliminary design is a straightforward, effective and relatively inexpensive approach to such measurements, and, for economy, is based the use of several instruments and components presently on hand at our Center. For each millimeter-wave band, we propose to combine a conventional vector network analyzer (or spectrum analyzer for vector magnitude-only studies) and its companion tracking generator with a appropriate phase-locked source, and, with a waveguide harmonic mixer, PLDRO and several standard microwave components, realize an economical but high-performance scalar network analyzer. Our design is unique in that it is based on and offers the performance advantages of a cost-effective, high-dynamic range block converter, in this case combined with a millimeter-wave source which is phase-locked to the conventional vector network analyzer (or spectrum analyzer/tracking generator). This pairing allows us to realize an instrument of exceptional capability through the higher millimeter-wave frequency bands. We will only need to construct a fast divider (or, alternatively, substitute a frequency-specific PLDRO) and the mixer sections, since all other sub-systems are, or will be, on hand. Specifications at 170GHz are: sweep span of 10.0GHz and a dynamic range of 75dB for 20KHz resolution. Other millimeter-wave bands are to be addressed by substitution of appropriate source modules and waveguide-harmonic-mixers. Construction of a swept millimeter-wave analyzer based on this new design will be initiated during the ensuing Center grant renewal period.