A. N. Datta

Bio: A. N. Datta is an academic researcher. The author has contributed to research in topics: Faraday effect & Faraday rotator. The author has an hindex of 2, co-authored 6 publications receiving 36 citations.

Techniques for the Measurement of Complex Microwave Conductivity and the Associated Errors

Abstract: Complex microwave conductivity of 9 /spl Omega/ /spl dot/ cm p-type silicon samples has been measured using conventional reflection and transmission bridges to examine their relative advantages and disadvantages. An attempt has been made to improve the reflection results from an analysis of the parameters of a circle diagram for reflection coefficient obtained on using a variable reactive termination after the semiconductor-filled waveguide section. In conformity with the calculated accuracy attainable from different types of measurement under the actual experimental condition, using commercial standards, the dielectric constant for the sample was found to be scattered over a region of /spl plusmn/0.4. It has been concluded that because of lack of accuracy in commercial standards for attenuation and phase shift, the potential accuracy of the conventional microwave methods falls too short of its mark to make any detinite conclusion about the effective mass of carriers in semiconductors at room temperatures.

Microwave faraday rotation in nickel-powder artificial dielectric - A suggested explanation

Abstract: It is shown that the anisotropic permeability of the magnetic particles constituting an artificial dielectric provides an explanation for the rotation of the plane of polarization and the variation of the attenuation of a plane‐polarized electromagnetic signal propagating through the dielectric in the presence of a longitudinal magnetic field. The attenuation curve is found to be readily explainable from the nature of variation of the power transmitted into the particles. A more detailed agreement between experimentally observed rotation, attenuation, and computed values is shown to follow if Lewin's formulas for the permeability and permittivity of an artificial dielectric is assumed to be valid also for circularly polarized signals. The effect of the size and permeability of the metal particles on the figure of merit of rotation is also discussed.

On microwave methods for the measurement of effective mass of carriers in semiconductors

Abstract: Available microwave methods for the measurement of effective mass of carriers in semiconductors are discussed and two other possible methods using only microwave data and requiring no assumption about the energy dependence of the momentum relaxation time of the carriers are suggested.

Electromagnetic Characterisation of Materials by Using Transmission/Reflection (T/R) Devices

Abstract: An overview of transmission/reflection-based methods for the electromagnetic characterisation of materials is presented. The paper initially describes the most popular approaches for the characterisation of bulk materials in terms of dielectric permittivity and magnetic permeability. Subsequently, the limitations and the methods aimed at removing the ambiguities deriving from the application of the classical Nicolson–Ross–Weir direct inversion are discussed. The second part of the paper is focused on the characterisation of partially conductive thin sheets in terms of surface impedance via waveguide setups. All the presented measurement techniques are applicable to conventional transmission reflection devices such as coaxial cables or waveguides.

Broad-Band Permittivity Measurements Using the Semi-Automatic Network Analyzer (Short Paper)

Abstract: This paper outlines the use of the network analyzer to measure the dielectric properties of materials over a broad frequency range. The method described here is based on transmission techniques with simple procedures for obtaining initial estimates and unambiguous solutions for the dielectric parameters. A further feature is that this measurement technique provides a degree of self-checking for inconsistent results.

Elimination of the multiple-solutions ambiguity in permittivity extraction from transmission-only measurements of lossy materials

Abstract: A simple yet powerful method is proposed for removing the multiple solutions problem in the complex permittivity, ϵ, determination from measured transmission scattering (S-) parameter measurements of lossy materials. The method uses amplitude-only measurements at two slightly separated frequencies to estimate an accurate initial guess. For this purpose, we derive a one-variable objective function for fast evaluation, which lends itself to measurement automation. The method provides an estimation for real and imaginary parts of the ϵ, which can be utilized as a measure for checking the correctness of initial ϵ estimate. The method is very useful for band-limited measurements. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 337–341, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24048

Cavity Perturbation Techniques for Measurement of the Microwave Conductivity and Dielectric Constant of a Bulk Semiconductor Material

Abstract: Cavity perturbation techniques offer a very sensitive highly versatile means for studying the complex microwave conductivity of a bulk material. A knowledge of the cavity coupling factor in the absence of perturbation, together with the change in the reflected power and the cavity resonance frequency shift, are adequate for the determination of the material properties. This eliminates the need to determine the Q-factor change with perturbation which may lead to appreciable error, especially in the presence of mismatch loss. The measurement accuracy can also be improved by a proper choice of the cavity coupling factor prior to the perturbation.

An uncertainty analysis for the measurement of microwave conductivity and dielectric constant by the short-circuited line method

Abstract: The uncertainties of conductivity σ and dielectric constant e of the short-circuited line (SCL) method due to the measured errors in the VSWR and the position of standing-wave minimum are studied. In order to cover most of the fast ion conductors, the range of σ from 10-4 to 1.0/(Ω-cm) is considered. The results of the analysis provide the order of accuracy one can achieve in these measurements. The effects of sample thickness, high conductivity, and negative dielectric constant upon uncertainty are examined. Measurements on a chlorobenzene sample are used to simulate this analysis. A relationship between σ, e, and operating frequency is derived which makes it possible to determine the limits of applicability of the SCL method.