1,976,491 research outputs found
Fundamental issues in antenna design for microwave medical imaging applications
No full textThis paper surveys the development of microwave medical imaging and the fundamental challenges associated with microwave antennas design for medical imaging applications. Different microwave antennas used in medical imaging applications such as monopoles, bow-tie, vivaldi and pyramidal horn antennas are discussed. The challenges faced when the latter used in medical imaging environment are detailed. The paper provides the possible solutions for the challenges at hand and also provides insight into the modelling work which will help the microwave engineering community to understand the behaviour of the microwave antennas in coupling media
New thermocouple-based microwave/millimeter-wave power sensor MMIC techniques in GaAs
No full textWe describe a new RF and microwave power sensor monolithic microwave integrated circuit design. The circuit incorporates a number of advances over existing designs. These include a III–V epitaxial structure optimized for sensitivity, the figure-of-merit applicable to the optimization, a mechanism for in-built detection of load ageing and damage to extend calibration intervals, and a novel symmetrical structure to linearize the high-power end of the scale
What does the future hold for microwave? "Microwave effect"
No full textAlthough we use microwave heating for chemical processes worth millions of dollars, the mechanism of the microwave heating is not very well understood. Progress in measuring local temperatures in microwave-heated transformations will allow us to search for any non-thermal microwave effect. It will also allow the use of microwave synthesis and catalysis much more effectively and in many more systems. This has the potential to be the key to huge energy savings and maintain environmental sustainability. Recent progress in microwave spectroscopy shows that it can be used for analytical applications in challenging environments, and perhaps for the separation of enantiomers.We acknowledge EPSRC Grant No. EP/H008403/1 awarded to Professor Brian J. Howard (Oxford University), the Centre for Public Engagement (Queen Mary, University of London) for funding, and Lis Carter for help in the recording
Microwave Radiation
No full textMicrowave radiation is a form of electromagnetic radiation. It covers, broadly speaking, frequencies between 300 MHz and 300 GHz. For example a microwave oven operates at a frequency of 2.45 GHz and many mobile network providers use frequencies between 800 MHz and 2.6 GHz. Microwave radiation has many applications including telecommunications, microwave ovens for our kitchens, military purposes, radar technology and air traffic control, radio astronomy and navigation, and to generate plasma and energy. In London and Oxford we use microwave spectroscopy to study complexes of nitric oxide.We acknowledge EPSRC Grant No. EP/H008403/1 awarded to Professor Brian J. Howard (Oxford University), the Centre for Public Engagement (Queen Mary, University of London) for funding, and Lis Carter for help in the recording
Investigation of microwave antennas in lossy media for medical applications
No full textFor several years, microwave engineers have dreamed of using non-ionising electromagnetic waves in medical imaging applications. The rate of evolution of microwave techniques for medical application has been immense and shows no signs of relenting. Since the limitations of X-ray mammography are well reported, alternative techniques using microwaves for breast cancer detection are developed. Some of these techniques have progressed to the point where positive clinical experience has emerged
Microwave Engineering Europe magazine articles regarding software suppliers benchmarking, including Optimization Systems Associates
No full textFile includes nine articles published in Microwave Engineering Europe magazine between 1990 and 1997, comparing responses to specific engineering problems and state-of-the-art advancements to engineering design. These works are licensed under a Creative Commons Attribution-Non-Commercial-No-Derivatives 4.0 International License.Microwave Engineering Europe was a professional magazine for engineers and management working in the RF, microwave, and wireless industry in Europe. Optimization Systems Associates Inc. (OSA) was established in 1983 by Dr. John W. Bandler and provided the engineering community with state-of-the-art CAD technology advancements in optimization methodology. The company was acquired by Hewlett-Packard in 1997. Microwave Engineering Europe published several articles referring to OSA, including benchmarking OSA’s responses to CAD challenges issued to industry and researchers
What does the future hold for microwave? Medicine
No full textThere are certain limitations and problems with using microwave radiation for diagnostic and therapeutic purposes, such as the spatial resolution, the penetration depth, the ability to focus the radiation, and the electromagnetic interference. Radiation, in general, can cause cancer but can also kill cancer cells. Microwave ablation may be used to fight cancer, and microwave radiation can in principle be used to detect any abnormalities in electrical properties of tissue, which might be indicative of cancer. Given that microwave is a non-ionizing radiation, it seems that it might become an additional, complementary tool in fighting cancer.We acknowledge EPSRC Grant No. EP/H008403/1 awarded to Professor Brian J. Howard (Oxford University), the Centre for Public Engagement (Queen Mary, University of London) for funding, and Lis Carter for help in the recording
An investigation of minerals using microwave measurement of complex permittivity
No full textIncludes bibliography.Microwave measurement techniques have found many industrial and commercial applications. This measurement potential of microwaves, together with observations that different minerals show different microwave heating characteristics, suggests the possibility of applying microwave techniques to various forms of mineral analysis. Simple, low cost, on-line mineral analysis techniques are of interest to the mining industry. The objectives of this research project were to cover the background theory of microwave interaction with minerals and to investigate different microwave measurement techniques that could possibly be applied to mineral measurement. Measurements were then to be performed on selected minerals in order to observe any differences between them. Finally, to comment on the feasibility of using microwave measurement techniques for the differentiation, identification and analysis of minerals
The microwave digestion of solids
No full textBibliography: leaves 115-116.Microwave ovens have been available for domestic cooking since 1956. This method of heating is very efficient compared to conventional cooking methods. As a result many applications have arisen particularly in the field of analytical chemistry. Most routine analysis of biological and chemical samples by atomic absorption spectroscopy (AAS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) involves the time consuming operation of digesting the samples in acid on a hot plate. However, much time saving has been demonstrated by the use of microwave digestion, and successful digestions have been achieved in 10% of the time required for traditional methods. The first digestions using microwave heating were performed in open vessels. However many problems were identified
Noise considerations when determining phase of large-signal microwave measurements
No full textAdvances in microwave instrumentation now make it feasible to accurately measure not only the magnitude spectrum, but also the phase spectrum of wide-bandwidth signals. In a practical measurement, the spectrum is measured over a finite window of time. The phase spectrum is related to the position of this window, causing the spectrum to differ between measurements of an identical waveform. It is difficult to compare multiple measurements with different window positions or to incorporate them into a model. Several methods have been proposed for determining the phase spectrum such that multiple measurements can be effectively compared and utilized in models. The methods are reviewed in terms of the information required to determine the phase and compared in terms of their robustness in the presence of measurement noise
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