Title :
High-Q thermoelectric-stabilized sapphire microwave resonators for low-noise applications
Author :
Tobar, Michael E. ; Giles, Adrian J. ; Edwards, Simon ; Searls, Jesse H.
Author_Institution :
Dept. of Phys., Western Australia Univ., Nedlands, WA, Australia
fDate :
5/1/1994 12:00:00 AM
Abstract :
Two low-noise high-Q sapphire-loaded cavity (SLC) resonators, with unloaded Q values of 2/spl times/10/sup 5/ and very low densities of spurious modes, have been constructed. They were designed to operate at 0/spl deg/C with a center frequency of 10.000000 GHz. The cavity was cooled with a thermoelectric (TE) Peltier element, and in practice achieved the required center frequency near 1/spl deg/C. The resonator has a measured frequency-temperature coefficient of -0.7 MHz/K, and a Q factor which is measured to be proportional to T/sup -2.5/. An upper limit to the SLC residual phase noise of /spl Lscr/ (100) Hz=-147 dBc/Hz, /spl Lscr/ (1 kHz)=-155 dBc/Hz, and /spl Lscr/ (10) kHz=-160 dBc/Hz has been measured. Also, we have created a free-running loop oscillator based on one of the SLC resonators, and measured a phase noise of /spl Lscr/(f)/spl sim/-10-30log [f] dBc/Hz between f=10 /Hz and 25 kHz, using the other as a discriminator.<>
Keywords :
Q-factor; cavity resonators; cooling; dielectric resonators; electron device noise; microwave oscillators; sapphire; thermoelectric devices; 0 C; 1 C; 10 Hz to 25 kHz; Q factor; SLC residual phase noise; center frequency; free-running loop oscillator; high-Q thermoelectric-stabilized sapphire microwave resonators; low densities; low-noise applications; measured frequency-temperature coefficient; phase noise; sapphire-loaded cavity resonators; spurious modes; thermoelectric Peltier element; unloaded Q values; Dielectric losses; Frequency measurement; Noise measurement; Phase measurement; Phase noise; Q factor; Q measurement; Temperature; Thermoelectricity; Voltage control;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
