# Method of measuring loaded Q-factor of single-ended cavity resonators using reflection bridge.

01 Mar 1978-Review of Scientific Instruments (American Institute of Physics)-Vol. 49, Iss: 3, pp 378-379

TL;DR: A bridge method of determining the loaded Q-factor and coupling coefficient of single-ended cavity resonators is described, using an oscillator with variable frequency amplitude modulation as the source.

Abstract: A bridge method of determining the loaded Q‐factor and coupling coefficient of single‐ended cavity resonators is described. The measuring system consists of a hybrid‐T or ’’magic T’’ bridge with one of the collinear arms terminated by the cavity and the other by a precision attenuator followed by a variable precision short. The experimental procedure essentially measures the reflection coefficient of a cavity resonator as a function of frequency by balancing the bridge, using an oscillator with variable frequency amplitude modulation as the source.

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01 Aug 1990

TL;DR: In this article, the authors reduce many of these expressions to two basic forms, a scalar or vectorial expression, that permits a similar treatment, and a brief description of a method for the processing each expression and some results are presented.

Abstract: Resonators are coupled to external circuits in different ways. It is possible to measure several magnitudes in each configuration, e.g., the transmission or reflection coefficients. There are different expressions that relate the measured magnitudes to the resonator's characteristic parameters. In the paper the authors reduce many of these expressions to two basic forms, a scalar or vectorial expression, that permits a similar treatment. A brief description of a method for the processing each expression and some results are presented.

23 citations

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15 Apr 2005TL;DR: A review of both traditional and modern methods of Q factor measurement can be found in this paper, including the particular advantages and disadvantages of a technique, the equipment required for the measurement, and its potential for accuracy.

Abstract: This article presents a review of both traditional and modern methods of Q factor measurement. Many of the techniques to be described were first developed in order to determine the Q factors of resonances falling in the microwave frequency domain.
The article commences with a definition of the Q factor and a description of the experimental parameters that need to be measured so as to determine the Q factor of resonance. The various methods for measuring these parameters will then be outlined, including the particular advantages and disadvantages of a technique, the equipment required for the measurement, and its potential for accuracy. Finally, some of the latest developments in the field of Q measurement will be presented.
Keywords:
Q;
microwave measurements;
resonators;
resonance parameters;
loss factor

15 citations

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TL;DR: A new cavity perturbation technique is presented for microwave measurement of dielectric constant, which uses a modified cylindrical reentrant cavity, and has the advantages of sample area and calibration of the measuring system with known dielectrics not necessary.

Abstract: A new cavity perturbation technique is presented for microwave measurement of dielectric constant, which uses a modified cylindrical reentrant cavity. Though suitable for only low dielectric constants, the method has the advantages, (a) sample area does not appear in the calculations, (b) only the ratio of frequency shifts due to two samples of same area and different thickness is involved, and (c) calibration of the measuring system with known dielectric is not necessary.

11 citations

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TL;DR: In this paper, a long cylindrical reentrant cavity having dimensions similar to those used for Gunn oscillators and for studies on semiconductors is presented for experimentally-determined tuning characteristics.

Abstract: Experimentally-determined tuning characteristics are presented for a long cylindrical re-entrant cavity having dimensions similar to those used for Gunn oscillators and for studies on semiconductors. The results indicate the simultaneous existence of the dominant TEM and the fundamental TE modes of resonance. A perturbation technique is given for the identification of the modes. Theoretical calculations of the resonant frequencies using simple models are presented. Experimental values of the Q-factors of the resonator for both the modes of resonance are also given.

4 citations

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TL;DR: In this paper, the performance characteristics of a 35 GHz cavity stabilized Gunn diode oscillator were analyzed and the frequency variations were reduced by a factor of 66 when the oscillator was locked to the cavity.

Abstract: The performance characteristics of a 35-GHz cavity stabilized Gunn diode oscillator is presented. The frequency variations are found to be reduced by a factor of 66 when the oscillator is locked to the cavity. © 1994 John Wiley & Sons, Inc.

2 citations

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TL;DR: In this article, a bridge method for simultaneous measurements of the coupling coefficient and the loaded Q of a single-ended cavity is described, which consists of a ''magic T'' bridge and incident power monitor circuits.

Abstract: A bridge method which allows the simultaneous measurements of the coupling coefficient and the loaded Q of a single‐ended cavity is described. The measuring system consists of a ``magic T'' bridge and incident power monitor circuits. Two collinear arms of the magic T are terminated by the cavity under measurement and the built‐in short at equal distances. Measurements are made by comparing the reflected power from the bridge with the incident power on the cavity.

9 citations