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  • 1
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    Measurement and analysis of a microwave oscillator stabilized by a sapphire dielectric ring resonator for ultra-low noise (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Phase-noise measurements are presented for a microwave oscillator whose frequency is stabilized by a whispering-gallery sapphire ring resonator with Q of 200,000. This mode involves little metallic conduction and allows nearly full use of the very low dielectric loss in sapphire. Several mode families have been identified, in good agreement with frequency calculations. For a 5-cm wheel resonator in a 7.6-cm container, Q values above 100,000 were found at room temperature for all of the modes in this sequence. Coupling Q-values for these same modes ranged from 10,000 (n = 5) to 100,000 (n = 10) for a WR112 waveguide port at the center of the cylinder wall of the containing can. Phase noise measurements for a transistor oscillator locked to the n = 10 (7.84-GHz) mode showed a 1/f cubed dependence for low offset frequencies, and a value of L(f) = -55 dB/Hz at an offset of 10 Hz from the carrier.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control (ISSN 0885-3010); 37; 339-346
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    NASA TECHNICAL REPORTS
  • 2
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    Microwave applications and characterization of the microwave properties of high temperature superconducting films (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The development by NASA JPL of high-temperature superconductors (HTSs) for use in microwave circuit elements is discussed. The synthesis of HTS films and characterization of their microwave absorption are reviewed. Applications to cryogenic low-noise receivers, spacecraft microwave systems, and low-noise oscillators are considered.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    A lead-on-sapphire superconducting cavity of superior quality (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A cavity consisting of a superconducting lead film on a sapphire substrate has been fabricated to obtain the enhanced frequency stability possible with this configuration. The cavity exhibits a quality value Q exceeding 2 x 10 to the 9th in its TE011 mode with a resonant frequency of 2.689 GHz. Methods of fabrication and testing of the cavity are presented. Since the interface between the film and substrate is exposed ot the full value of the resonant magnetic field, the present experiment is the most sensitive test to date for enhanced losses at the interface itself. No evidence of such losses is used. In fact, the measured values of the surface resistance match very well predictions for RF losses based on the BCS theory.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Applied Physics (ISSN 0021-8979); 59; 854-858
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    NASA TECHNICAL REPORTS
  • 4
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    Low noise cryogenic dielectric resonator oscillator (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A microwave oscillator is provided which can operate at a temperature of many degrees above absolute zero while providing very low phase noise that has heretofore generally required temperatures within a few degrees K. The oscillator includes a ring-shaped resonant element of ruby (sapphire plus chromium) or iron sapphire crystal, lying adjacent to a resonator element of sapphire, so that the regenerator element lies directly in the magnetic field of the resonator element. The resonator element is substantially devoid of contact with electrically conductive material. Microwave energy of a pump frequency (e.g., 31 GHz) is outputted from the regenerator element, while signal energy (e.g., 10 GHz) is outputted from the resonator element.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Format: application/pdf
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  • 5
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    A receiver design for the superconducting cavity-maser oscillator (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A new frequency standard was demonstrated with the aid of a double phase locked loop (PLL) receiver. A superconducting cavity maser oscillator (SCMO) and a hydrogen maser are combined to show the medium term performance of the hydrogen maser together with improved short term performance made possible by the SCMO. The receiver, which generates a 100 MHz signal with reduced noise, is phase locked to (and may be used in place of) the 100 MHz hydrogen maser output. The maser signal, 2.69xxx-GHz SCMO output, and a 100 MHz quartz crystal oscillator are optimally combined by the receiver. A measured two source fractional frequency stability of 2 x 10(exp -14) was obtained for a measuring time of r = 1 sec, and 1 x 10(exp -15) at r = 1,000 sec. The 1 sec value is approx. 10 times lower than that for hydrogen masers, while the 1,000 sec value is identical to hydrogen maser performance. The design is based on phase noise models for the hydrogen maser, the SCMO, and quartz crystal oscillators for offset frequencies down to 1 x 10(exp -6) Hz.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 1-11
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    NASA TECHNICAL REPORTS
  • 6
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    Microwave oscillator with reduced phase noise by negative feedback incorporating microwave signals with suppressed carrier (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Oscillator configurations which reduce the effect of 1/f noise sources for both direct feedback and stabilized local oscillator (STALO) circuits are developed and analyzed. By appropriate use of carrier suppression, a small signal is generated which suffers no loss of loop phase information or signal-to-noise ratio. This small signal can be amplified without degradation by multiplicative amplifier noise, and can be detected without saturation of the detector. Together with recent advances in microwave resonator Qs, these circuit improvements will make possible lower phase noise than can be presently achieved without the use of cryogenic devices.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 20-33
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  • 7
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    Measurement and analysis of cryogenic sapphire dielectric resonators and DROs (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Presented are the experimental and computational results of a study on a new kind of dielectric resonator oscillator (DRO). It consists of a cooled, cylindrically symmetric sapphire resonator surrounded by a metallic shield and is capable of higher Q's than any other dielectric resonator. Isolation of fields to the sapphire by the special nature of the electromagnetic mode allows the very low loss of the sapphire itself to be expressed. Calculations show that the plethora of modes in such resonators can be effectively reduced through the use of a ring resonator with appropriate dimensions. Experimental results show Q's ranging from 3 x 10 to the 8th at 77 K to 10 to the 9th at 4.2 K. Performance is estimated for several types of DROs incorporating these resonators. Phase noise reductions in X-band sources are indicated at values substantially lower than those previously available.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 73-80
    Format: application/pdf
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