Milestones of microwaves

Sobol, H.; Tomìyasu, K.

doi:10.1109/22.989945

Cited by 39 publications

(15 citation statements)

References 75 publications

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“…Microwave technology developed rapidly during Second World War due to the demand for better radar technology for detection of enemy aircraft and submarines. During this period, the applications of microwaves were mainly restricted to radar and communications with limited studies on the use of microwaves for heating of tissues in therapeutic applications [1,2]. Interest in microwave heating applications started towards the end of World War II when major manufacturers of microwave tubes, such as Westinghouse, General Electric and Raytheon, started to look into alternative uses for microwave tubes, and filed many patents to make use of microwave heating for industrial applications, such as drying of tires, textiles, and wood; commercial processing; and treatment of food.…”

Section: Brief History and Applications Of Microwave Heatingmentioning

confidence: 99%

“…Therefore the high sintering temperature near the melting point of the metal will enhance the absorption of microwaves by the metal. The number of vacant atomic sites and the number of atoms with sufficient energy to move into the vacant sites are related with an Arrhenius equation as shown in Equation (2): (2) where N/N0 is the ratio of available sites or activated atoms to total atoms, Q is the activation energy, R is the gas constant and T is the absolute temperature. Since sintering is a thermally activated process, higher sintering temperatures can significantly shorten the sintering time.…”

Section: Hybrid Microwave Sintering Techniquementioning

confidence: 99%

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Using Microwave Energy to Synthesize Light Weight/Energy Saving Magnesium Based Materials: A Review

Wong

Gupta

2015

Technologies

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Microwave energy can be used for the processing of a wide variety of materials. It is used most commonly for the heating of food and has been increasingly applied for processing of polymers; ceramics; metals; minerals and composites. The use of microwave energy allows rapid and volumetric heating where heat is generated from within the material instead of via radiative heat transfer from external heating elements. This paper aims to provide a review on the use of energy efficient and environment friendly microwave energy route to synthesize magnesium based materials reinforced with various types of metallic and ceramic reinforcements. Magnesium composites are extremely attractive for weight critical applications in automotive; aerospace; electronics and transportation sectors. The magnesium composites were prepared using blend-compact-microwave sintering-extrusion methodology. Microwave sintering allowed a significant reduction of 80% in both processing time and energy consumption over conventional sintering without any detrimental effect on the properties of the synthesized magnesium composites. Physical; microstructure and mechanical properties of microwave sintered magnesium composites will also be discussed and compared with magnesium composites processed by conventional liquid and solid processing techniques. OPEN ACCESSTechnologies 2015, 3 2

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Section: Brief History and Applications Of Microwave Heatingmentioning

confidence: 99%

Section: Hybrid Microwave Sintering Techniquementioning

confidence: 99%

Using Microwave Energy to Synthesize Light Weight/Energy Saving Magnesium Based Materials: A Review

Wong

Gupta

2015

Technologies

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“…The term micro-wave was first coined by A.G. Clavier in a paper published in 1931 by the International Telephone and Telegraph to describe the propagation of an 18 cm wavelength radio link from Dover, UK to Calais, France [2]. The term micro-wave was first coined by A.G. Clavier in a paper published in 1931 by the International Telephone and Telegraph to describe the propagation of an 18 cm wavelength radio link from Dover, UK to Calais, France [2].…”

mentioning

confidence: 99%

Introduction to Microwaves

Gupta

Leong

2007

Microwaves and Metals

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“…Modulation schemes, such as orthogonalfrequency-division multiplexing (OFDM), and quadrature amplitude modulation (QAM) are used in modern wireless communication systems to maximize the spectral efficiency [2]. These modulation schemes result in signals with large amplitude variations and peak to average power ratios (PAPRs) in the range of 6-12 dB [4,5]. In order to prevent strong distortion of the signal, these signals require the PA to operate at an average output power far below from the saturation region and hence, at low-efficiency levels.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of GaN-HEMT power amplifiers using BST-based components for load modulation

Arnous

Wiens

Saad

et al. 2014

Int. J. Microw. Wireless Technol.

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In this paper, the concept of load-modulated power amplifiers (PAs) is studied. Two GaN-HEMT power amplifiers (PAs), targeted for high efficiency at maximum and output back-off (OBO) power levels, are designed, implemented, and tested across 1.8-2.2 GHz. The load modulation in the first design is realized by tuning the shunt capacitors in the output matching network. A novel method is employed in the second design, where barium-stronrium-titante is used for the realization of load modulation. The large-signal measurement results across the desired band show 59-70% drain efficiency at 44-44.5 dBm output power for both designs. Using the available tunable technique, the drain efficiency of the PAs is enhanced by 4-20% at 6 dB OBO across the bandwidth. I . I N T R O D U C T I O NOwing to the rapid growth of subscribers in wireless communication systems [1] and the emergence of new communication standards, such as worldwide interoperability for microwave access (WIMAX) and 4 G long-term evolution (LTE), the mobile radio base stations (RBSs) must process different types of standards in increasing number of frequency bands. At the core of the RBS, the power amplifier (PA) is one of the most critical components since its performance affects the overall system performance in terms of output power, bandwidth, and efficiency [2,3]. Modulation schemes, such as orthogonalfrequency-division multiplexing (OFDM), and quadrature amplitude modulation (QAM) are used in modern wireless communication systems to maximize the spectral efficiency [2]. These modulation schemes result in signals with large amplitude variations and peak to average power ratios (PAPRs) in the range of 6-12 dB [4,5]. In order to prevent strong distortion of the signal, these signals require the PA to operate at an average output power far below from the saturation region and hence, at low-efficiency levels.Various techniques have been proposed to enhance the efficiency of PAs at back-off operation. Dynamic supply modulation (DSM) [6,7] and dynamic load modulation (DLM) [8] have proven themselves to be the most promising methods. The DSM method requires efficient DC/DC converter as well as efficient envelope tracking amplification, whereas the DLM may be realized using extra active devices as implemented in Doherty amplifiers [9] or using passive components [10]. In terms of cost, complexity, and additional power consumption, DLM using passive components seems to be more efficient than DSM and Doherty amplifiers in spite of the challenges in the dynamic range of power detector and the required speed to follow the envelope variation. DLM can be realized by tunable matching networks (TMNs) using conventional passive components such as micro-electro-mechanical systems (MEMS) [10] semiconductor or ferroelectric-based varactors [11]. Alternatively, passive load modulation technique using barium-strontium-titanate (BST) varactors can be implemented [12]. Recently, thick-film BST components have demonstrated promising perspectives in terms of tunability with high...

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Milestones of microwaves

Cited by 39 publications

References 75 publications

Using Microwave Energy to Synthesize Light Weight/Energy Saving Magnesium Based Materials: A Review

Using Microwave Energy to Synthesize Light Weight/Energy Saving Magnesium Based Materials: A Review

Introduction to Microwaves

Evaluation of GaN-HEMT power amplifiers using BST-based components for load modulation

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