Yueyan Shan

Generic Model and Case Studies of Microwave Power Sensor Calibration Using Direct Comparison Transfer

This paper proposes a generic model for analyzing the microwave power sensor calibration by direct comparison transfer. The model is derived using a signal flow graph together with nontouching loop rule analyses. The proposed model is investigated through several case studies which are commonly encountered and provides a theoretical basis for practical applications. Finally, realizations of the derived calibration equations for some practical cases are also discussed.

Development of a 50 GHz coaxial direct comparison transfer microwave power sensor calibration system at NMC

This paper describes the continuous development of NMCs microwave power sensor calibration system using the direct comparison transfer method. The system uncertainties are evaluated for the complex reflection coefficient inputs in terms of real and imaginary components and its magnitude and phase format following the internationally recommended guidelines. Monte Carlo method is also used to numerically check the distribution of the output quantities. The measurement results and the uncertainties in different methods are presented and discussed.

Comparison of S-Parameter Measurements at Millimeter Wavelengths Between INRIM and NMC

This paper describes a bilateral comparison between two national metrology institutes, National Metrology Center from Singapore and Istituto Nazionale di Ricerca Metrologica from Italy. The measurands of the comparison are the scattering parameter magnitudes of waveguide components of type WR15 (50-75 GHz) and WR10 (75-110 GHz). This comparison is, to the best of our knowledge, the first of this kind performed so far. The measurement results are also compared with electromagnetic computations based on mechanical measurements on a subset of the traveling standards.

Measurement Uncertainty of Complex-Valued Microwave Quantities

This paper presents an evaluation of measurement uncertainty for complex-valued quantities in microwave applications, mainly focusing on the non-linear transformation of measurement uncertainty from rectangular coordinate to polar coordinate. Based on the law of propagation of uncertainty in matrix form, general expressions of the covariance matrix for the magnitude and phase uncertainties in polar coordinate have been derived, and several difierent application scenarios have been analyzed and evaluated with numerical simulations. This is followed by some recommendations on the coordinate transformations in practical microwave measurements.

Evaluation of a Calorimetric Thermal Voltage Converter for RF–DC Difference up to 1 GHz

In this paper, we present a performance evaluation of the RF-DC transfer difference for a calorimetric thermal voltage converter (CTVC) designed by the National Research Council of Canada (NRC) at frequencies up to 1 GHz. In the first part of this paper, we describe a bilateral comparison of the RF-DC difference standards between the NRC and the National Metrology Centre of the Agency for Science, Technology and Research of Singapore, in the frequency band from 1 kHz to 100 MHz. A good agreement is observed between the two laboratories using the CTVC as a traveling standard. In the second part of this paper, we evaluate the performance of the CTVC at higher frequencies up to 1 GHz. In this part, RF-DC difference of the CTVC is mathematically modeled and experimentally evaluated in terms of the calibration factor of a thermistor mount and the reflection coefficients at its type-N input connector.

Evaluation of complex measurement uncertainty in polar coordinate for equivalent source reflection coefficient

This paper presents a method for evaluating the complex measurement uncertainty in polar coordinate for equivalent source reflection coefficient in direct comparison transfer of microwave power sensor calibration. The method is based on the law of propagation of uncertainty in matrix form. In this paper, general expressions of the covariance matrix for the magnitude and phase uncertainties are derived, and different application scenarios are investigated.

Development of a waveguide microwave power sensor calibration system at NMC

In this paper, the development of a waveguide microwave power sensor calibration system is reported. This system is a physical realization of the direct comparison transfer of waveguide microwave power sensor calibration up to 110 GHz. For the developed calibration system, the measurement uncertainty is discussed and evaluated, where the major uncertainty contributor for the current system is identified. To further improve the performance of our system and reduce the cost of calibration, some necessary future work is planned.

Electromagnetic interference shielding effectiveness of carbon-nanotubes based coatings

Electromagnetic interference shielding coatings based on multi-walled carbon nanotubes are prepared and studied. The electromagnetic shielding effectiveness (SE) from 10 MHz to 3 GHz is measured using frequency and time domain methods. The results show that MWCNT coatings are more effective in providing EMI shielding in broad-band frequency range at thin coating layer.

Bilateral comparison between NMC and INRIM on microwave power sensor using type N and 3.5 mm connectors

This paper describes the bilateral comparison between two national metrology institutes, NMC from Singapore and INRIM from Italy, concerning microwave power measurements with coaxial lines using type N (up to 18 GHz) and 3.5 mm (up to 26.5 GHz) connectors.

An Improved Design and Simplified Evaluation Technique for Waveguide Microcalorimeter

An improved design and simplified evaluation technique for waveguide microcalorimeter is presented in this paper. The design is based on a traditional twin-line microcalorimeter for calibrating thermistor mounts but with a proposed novel modification. In the improved design, another thermistor is added to measure the temperature change of the thermal isolation waveguide section. A simplified evaluation method is also proposed to minimize the S-parameter measurements for obtaining the effective efficiency of the mount. The measurement model and its detailed derivation are discussed. The capability of the improved design and proposed evaluation technique has been assessed through a recent consultative committee for electricity and magnetism key comparison.