2-MM WAVE VECTOR NETWORK ANALYZER UPON HIGH-ORDER IMPATT MULTIPLIERS
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2-MM WAVE VECTOR NETWORK ANALYZER UPON HIGH-ORDER IMPATT MULTIPLIERS Gennadiy P. Ermak, Anton V. Varavin Usikov Institute for Radiophysics and Electronics of National Academy of Sciences of Ukraine 12, Akad. Proskura str., 61085 Kharkov, Ukraine Received 8 March 2005 Abstract This paper shows the first results of development of the 2 millimeter-wave vector network analyzer (VNA) based on active high-order IMPATT multipliers – the new type of harmonic generators. The multipliers of this type can translate the spectra of highly stable centimeter-wave oscillators to any part of the millimeter range with the output power of 20÷13 dBm without additional amplification. Against Schottky-diode multipliers that are used in conventional VNAs, the active IMPATT multipliers generate more output power at large harmonic numbers that allows to lock the multipliers at their output frequencies.The phase noise of IMPATT multipliers is proportional to N against N2 in the Schottky-diode multipliers (where N is the harmonic number). We have investigated the scheme of the VNA in which the PLL and receiving mixers operated at the fundamental frequency of the heterodyne. Keywords: Millimeter wave, Vector network analyzer, Phase locking, IMPATT multipliers. 1. Introduction The purposeful recent advancement in atomic and molecular spectroscopy and dielectric measurements toward the short-wave end of the millimeter band seeks high-resolution amplitude and phase measuring systems. It is known that the most successful systems of the kind are the vector network analyzers (VNA). At the centimeter and millimeter waves, vector network analyzers (VNA) employ phase-locked YIG oscillators and varactor-tuned Gunn oscillators. To extend the VNA working range toward the short millimeter waves (including the submillimeter band), the Schottky-diode multipliers (doublers, triplers or their combinations) are used. However the output power of the Schottkydiode multipliers is low in this region so their locking is not easy there. 681
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A way toward the development of the short-millimeter solid-state coherent system is with signal sources based on active high-order IMPATT multipliers. Such multipliers can translate the spectra of highly stable centimeter-wave oscillators to any part of the millimeter range. Against varicap multipliers, IMPATT multipliers perform a multiplication well at large harmonic numbers, e.g. the phase noise of Schottky-diode multipliers are proportional to N2, where N is a harmonic number, and the phase noise of IMPATT multipliers is proportional to N. If the IMPATT crystal structure is such that the output frequency corresponds to the negative conductivity domain, the output signal is additionally amplified and, consequently, the conversion loss reduces [1]. The IMPATT multipliers can be very fast frequency tunable and used at the fast frequency synthesizers. 2. Description of the MVNA To purpose of the ESP spectroscopy, non-destructive testing, dielectrics and high-Q resonators characterisation the millimeter-wa
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