Solid-state generator of EHF range with increased long-term frequency stability

Abstract

A method for long-term frequency stabilization of a solid-state generator of the EHF range by maintaining a constant temperature of the resonant system is described. An open resonator with resonant frequency mainly determined by its length is used. The resonator temperature was controlled by a semiconductor sensor and the temperature stabilization was carried out using Peltier elements connected between the fuel element (Gunn diode) and the radiator. The multi-link matching of the active element and the open resonator, which rarefy the spectrum of the output signal in both transverse and longitudinal types of oscillations, was used to match a high-Q open resonator with a low-impedance source of electrical oscillations. The generation frequency with the Gunn diode was 36 GHz, the modulation characteristic of the generator S = Δfг /ΔUД = 6 MHz / V, output power was not less than 50 mW, accuracy of temperature control t = ± 1 0C in the range of external temperature changes -20 - + 30 0C, operating temperature was 35 0C. As a result, the open resonator generator had a frequency drift of less than 0.5 MHz for 7 hours. For comparison, the frequency drift of a similar generator with a waveguide resonator for the same time was about 20 MHz. In addition, the generator with an open resonator and thermal stabilization entered the frequency stabilization mode earlier. Frequency stability, estimated by the labels of the spectrum analyzer, is not worse than 1 ∙ 10-7 min-1. Long-term temperature stability (Δf/f)/ΔТ = ±1·10-6/0C. It should be noted that the resonator is excited on a quasi-basic type of oscillation, which allows additional frequency tuning by changing the length L of the resonator ~ 0.25 GHz with a decrease in the output power by 3 dB. A similar method could be used to create a solid-state sources with long-term stability in the 150-300 GHz frequency range.