U.S. Government work not protected by U.S. copyright Abstract A microwave power standard directly traceable to a fundamental atomic process could potentially reduce the uncertainties associated with microwave power measurement. We report on a proof-of-principle experiment to measure microwave power by observing Rabi oscillations in the clock transition of Cs atoms. The measurements were perform...

In microwave induced thermo-acoustic tomography (MITAT) system, radiation of an antenna is a near field problem which gives rise to a non-uniform distribution of microwave radiation power in detection area. Due to this non-uniform distribution, the contrast of MITAT image which is proportional to the absorbed microwave energy will not reflect the real characteristics (dielectric properties) of ...

A phase-locked coaxial transit time oscillator is designed for microwave sources with a small volume and low magnetic field in high-power coherent combining. The achieves controlled output phase through pre-modulation of electron beams. To improve the performance fields, reentrant input cavity used to ensure stability uniformity electric field. Electric buncher extractor also improved. reduce d...

We present microwave ~30 GHz! measurements on aluminum superconducting hot-electron bolometer ~HEB! mixers. Aluminum HEB mixers have a lower superconducting transition temperature than niobium and niobium nitride devices, and are predicted to have improved sensitivity and require less local oscillator power. The devices studied consist of a narrow superconducting aluminum microbridge with conta...

We report the use of in situ Raman spectroscopy as a probe for the effect of power on microwave-promoted Suzuki coupling reactions. We find that increased initial microwave power leads to greater acceleration of the reaction but that the product yield obtained is essentially independent of initial microwave power. The application of simultaneous cooling lengthens the reaction time but does not ...

The performance of a room temperature, zero-field MASER operating at 1.45 GHz has been examined. Nanosecond laser pulses, which are essentially instantaneous on the timescale of the spin dynamics, allow the visible-to-microwave conversion efficiency and temporal response of the MASER to be measured as a function of excitation energy. It is observed that the timing and amplitude of the MASER out...

Experimental study and SPICE simulation of CMOS digital circuits latch-up effects due to high power microwave interference are reported in this paper. As a traditional inherent destruction phenomenon, latch-up effect may jeopardize the correct function of the circuits, and could be triggered in various ways such as ESD pulse, cosmic ray, heavy ion particles etc. Through the directly injected ex...

Introduction The need for highly efficient, linear microwave power amplifiers has grown rapidly, especially as mobile and satellite communication systems have been developed and expanded [1]. These systems employ multilevel digital modulation techniques to achieve higher-data-rate and multimedia services. This results in a band-limited multi-carrier signal, which is spectrally efficient but exh...

Microwave-assisted and ultrasound-assisted extraction assays were used to isolate total flavonoids (TF) from Osmanthus fragrans flowers. The effects of the solid-liquid ratio, ethanol concentration, microwave power, microwave extraction time, ultrasonic power and ultrasonic extraction time on the yield of TF were studied. A sequential combination of microwave- and ultrasound-assisted extraction...