Bio: Max Sucher is an academic researcher. The author has contributed to research in topics: Microwave. The author has an hindex of 1, co-authored 1 publications receiving 324 citations.
01 Jan 1963
TL;DR: In this article, the design, construction, and operation of a new type of microwave spectrograph which allows the measurement of the resonant transitions of transient or otherwise short-lived species is described.
Abstract: We describe the design, construction, and operation of a new type of microwave spectrograph which allows the measurement of the resonant transitions of transient or otherwise short‐lived species. The spectrograph is composed of three parts: a Fabry–Perot cavity, a pulsed supersonic nozzle as a source for the sample, and the pulsed microwave Fourier transform method. Following a detailed discussion of the three above components in the spectrograph, the operation of the entire system is described and several examples are given.
TL;DR: A review of the properties of ferroelectric materials that are relevant to microwave tunable devices is presented in this article, where the theory of dielectric response of tunable bulk materials and thin films is discussed.
Abstract: A review of the properties of ferroelectric materials that are relevant to microwave tunable devices is presented: we discuss the theory of dielectric response of tunable bulk materials and thin films; the experimental results from the literature and from own work are reviewed; the correspondence between the theoretical results and the measured properties of tunable materials is critically analyzed; nominally pure, real (defected), and composite bulk materials and thin films are addressed. In addition, techniques for characterization of tunable ferroelectrics and applications of these materials are briefly presented.
01 Jan 2005
TL;DR: Venkatesh et al. as mentioned in this paper presented an overview of dielectric properties measuring techniques and their application in the agri-food sector, and the concept of various measurement methodologies and their development.
Abstract: Venkatesh, M.S. and Raghavan, G.S.V. 2005. An overview of dielectric properties measuring techniques. Canadian Biosystems Engineering/Le genie des biosystemes au Canada 47: 7.15 7.30. With a need for the development of improved sensing devices for the control and automation of several agricultural, environmental, and food processes, there is an absolute need for better understanding of the dielectric properties of materials and techniques for measuring these properties. Microwave measurements and the dielectric properties of materials are finding increasing application as new electro-technology is adapted for use in the agriculture and food processing industries. The interest in dielectric properties of materials has historically been associated with the design of electrical equipment, where various dielectrics are used for insulating conductors and other components of electric equipment. Measurement of the bulk dielectric properties (dielectric constant, dielectric loss factor) is not an end unto itself. Rather, these properties are an intermediary vehicle for understanding, explaining, and empirically relating certain physico-chemical properties of the test material. Therefore, in this paper, an attempt is made to fully explore the existing knowledge of dielectric properties (complex permittivity), their role, and importance in the agri-food sector, and the concept of various measurement methodologies and their development. We have summarized the current status of research in this area with some notes on recent developments. An extensive review of the literature on measuring techniques and the comparison and potential application of dielectric properties is reported. Readers are advised to follow the appropriate literature cited for detailed and complete reference.
TL;DR: In this paper, seven different methods to determine the resonant frequency and quality factor from complex transmission coefficient data are discussed and compared to find which is more accurate and precise when tested using identical data.
Abstract: Precise microwave measurements of sample conductivity, dielectric, and magnetic properties are routinely performed with cavity perturbation measurements. These methods require the accurate determination of quality factor and resonant frequency of microwave resonators. Seven different methods to determine the resonant frequency and quality factor from complex transmission coefficient data are discussed and compared to find which is most accurate and precise when tested using identical data. We find that the nonlinear least-squares fit to the phase versus frequency is the most accurate and precise when the signal-to-noise ratio is greater than 65. For noisier data, the nonlinear least-squares fit to a Lorentzian curve is more accurate and precise. The results are general and can be applied to the analysis of many kinds of resonant phenomena.
TL;DR: In this paper, the real and imaginary components of the complex relative permittivity at 298 K using microwave frequencies (2, 10, and 18-40 GHz) for bulk SiO2-aerogels and for two types of organic aerogels, resorcinol-formaldehyde (RF), were measured.
Abstract: We have measured the real (dielectric constant) and imaginary (loss factor) components of the complex relative permittivity at 298 K using microwave frequencies (2, 10, and 18–40 GHz) for bulk SiO2-aerogels and for two types of organic aerogels, resorcinol-formaldehyde (RF) and melamine-formaldehyde (MF). Measured dielectric constants are found to vary linearly between values of 1.0 and 2.0 for aerogel densities from 10 to 500 kg/m3. For the same range of densities, the measured loss tangents vary linearly between values of 2 × 10−4 and 7 × 10−2. The observed linearity of the dielectric properties with density in aerogels at microwave frequencies shows that their dielectric behavior is more gas-like than solid-like. The dielectric properties of aerogels are shown to be significantly affected by the adsorbed water internal to the bulk material. For example, water accounts for 70% of the dielectric constant and 70% of the loss at microwave frequencies for silica aerogels. Because of their very high porosity, even with the water content, the aerogels are among the few materials exhibiting such low dielectric properties. Our measurements show that aerogels with greater than 99% porosity have dielectric constants less than 1.03; these are the lowest values ever reported for a bulk solid material.