A high-efficiency class-E power amplifier is proposed for digital PWM microwave signal amplification in the improved Kahn Technique transceiver. The benefit of using a class-E power amplifier in this design approach is to improve efficiency of the power amplifier due to its switching mode operation, theoretically 100 % with ideal conditions. In this paper a class-E amplifier is designed for the...

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 ...

In this work, a fast and efficient microwave-assisted extraction (MAE) method was developed to extract main bioactive alkaloids from lotus plumue. To optimize MAE conditions, three main factors were selected using univariate approach experiments, and then central composite design (CCD). The optimal extraction conditions were as follows: methanol concentration of 65%, microwave power of 200 W, a...

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...

We demonstrate the compression of electron pulses in a high-brightness ultrafast electron diffraction instrument using phase-locked microwave signals directly generated from a mode-locked femtosecond oscillator. Additionally, a continuous-wave phase stabilization system that accurately corrects for phase fluctuations arising in the compression cavity from both power amplification and thermal dr...

In this paper, we present a “smart” high-peak power microwave tube, by implementing iterative learning control methodologies to control a repetitively-pulsed, high-power, backward wave oscillator. The learning control algorithm is used to drive the error between the actual output and its desired value to zero. The desired output may be a given power level, a given frequency, or a combination of...

In order to make precise measurements of laser frequencies in the infrared region, it is generally necessary to run a laser cw at a low power level. This is done to insure frequency stability that is very hard to obtain in high-power, Q-switched lasers. Microwave techniques such as heterodyning can be used for extremely accurate measurements of absolute laser frequencies, provided a radiation d...

The main drawbacks of microwave heating of bioproducts (e.g. foods) are associated with its nonuniform heating patterns. The objective of this work was to derive optimal operating policies for microwave combination ovens in order to achieve better uniformity of temperature and/or quality. The corresponding optimal control problems were stated considering the microwave power and the oven tempera...

We have developed a new technique for accurate measurement of the loss of superconducting microstrips at mm-wave frequencies. In this technique, we optically couple power to slot antenna, which is connected to one port of a hybrid coupler. One of the output ports of the hybrid delivers power to a series of mm-wave microstrip resonators which are capacitively coupled to a feedline followed by an...