California Institute of Technology

United States of America As Represented by the Administrator of Nasa

Applied Motion

G John Dick

Eric A Edwards

Jonathan E Saunders

David G Santiago

A sapphire resonator for an ultrastable oscillator capable of substantial performance improvements over the best available crystal quartz oscillators in a compact cryogenic package is based on a compensation mechanism enabled by the difference between copper and sapphire thermal expansion coefficients for so tuning the resonator as to cancel the temperature variation of the sapphire's dielectric constant. The sapphire resonator consists of a sapphire ring separated into two parts with webs on the outer end of each to form two re-entrant parts which are separated by a copper post. The re-entrant parts are bonded to the post by indium solder for good thermal conductivity between parts of that subassembly which is supported on the base plate of a closed copper cylinder (rf shielding casing) by a thin stainless steel cylinder. A unit for temperature control is placed in the stainless steel cylinder and is connected to the subassembly of re-entrant parts and copper post by a layer of indium for good thermal conduction. In normal use, the rf shielding casing is placed in a vacuum tank which is in turn placed in a thermos flask of liquid nitrogen. The temperature regulator is controlled from outside the thermos flask to a temperature in a range of about 40.degree. to 150.degree. K, such as 87.degree. K for the WGH.sub.811 mode of resonance in response to microwave energy inserted into the rf shielding casing through a port from an outside source.

Temperature compensated sapphire resonator for ultrastable oscillator

Microwave oscilltors incorporate r.f. feedback with carrier suppression to reduce phase noise. In a direct feedback oscillator arrngement a circulator is interposed between the r.f. amplifier and the high-Q resonator. The amplifier output is applied to the slightly over-coupled input port of the resonator so that the resultant net return signal is the vectorial difference between the signals emitted and reflected from the resonator. The gain of the r.f. amplifier is chosen to regenerate the forward signal from the net return signal. In a STALO-type arrangement, the resonator is critically coupled and an r.f. amplifier added to the path of the net return signal. The sensitivity of the STALO-type feedback loop is thereby enhanced while added amplifier noise is minimized by the superposition of the signals emitted by and reflected from the resonator.

Method and apparatus for reducing microwave oscillator output noise

A self-actuated spring-action human bipedal device includes a back-mounted frame attached to the upper torso of a user, and separate articulated right and left leg frames pivotally attached by U-joints to lower portions of the back frame. The user's feet are secured to the leg frames so the bottoms of the leg frames contact the ground, behind and below the point where each foot is attached to its leg frame. Endless cord-like main springs are engaged with a spring actuator, which are carried on the back frame. Left and right tension lines running from respective leg frames to the spring actuator are arranged so that compression of the leg frames, caused by the force of downward movement of the user's feet and torso, pulls on the tension lines to apply a pulling force to the spring actuator for stretching the main springs. The tension lines are also each attached to a part of the leg frame which engages on the user's foot so that extension of the user's leg pulls on the tension lines, also stretching the main springs. The energy stored in the stretched main springs is then transferred back to the torso of the user and to the user's feet to cause the user to jump into the air. Separate pick-up springs connected to each leg frame keep the tension lines under positive tension and apply a pick-up force to the leg frame to raise it and prevent dragging.

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Claremont, CA, United States of America

G John Dick