Thermistor controlled gunn oscillator at Ka-band

Miniature low-power submillimeter-wave spectrometer for remote sensing in the solar system

“…Frequency-temperature curves have been used for Gunn oscillator frequency stabilization in the past, with an accuracy of 25 MHz reported for a -band oscillator [11]. Another low-power technique, using a voltage compensation circuit to produce a constant frequency over a wide range of temperatures, has been recently reported for a -band Gunn oscillator as well, with similar accuracy (15 MHz) [12]. In our receiver, the 140-GHz LO frequency accuracy requirement is about an order of magnitude higher than those quoted in [11] and [12] since it must produce an IF signal which is always within the 10-MHz bandwidth of the IF filter.…”

“…Initially, the Gunn oscillator was connected directly to the frequency counter, but it was determined that an isolator was necessary since there was a large (5-40 MHz) frequencydependent frequency error. After adding an isolator between the Gunn oscillator and the frequency counter, the frequency error decreased (10)(11)(12)(13)(14)(15)(16), and a very strong temperature dependence was observed, with the error getting smaller as the temperature was increased. This was interpreted as an indication that the presence of water might be a problem and, consequently, the Gunn oscillator and isolator were placed in a zip-locked bag filled with desiccant pouches, and left to dry overnight.…”