Dimensionless Parameter
Dimensionless parameters characterize the efficiency of a resonant system by comparing the stored energy to the energy lost per cycle. The quality factor determines the sharpness of the resonance peak and the damping behavior of an oscillator. Higher values are achieved only in systems with very low internal resistance.
Resonant Performance
A high value indicates a narrow bandwidth and low energy dissipation within the circuit. The quality factor of an inductor is limited by the resistance of the wire and the losses in the core material. In filters, this value defines the selectivity and the ability to reject off frequency signals.
Mechanical systems such as tuning forks or quartz crystals can achieve very high values.
Measurement Technique
The quality factor is influenced by the load connected to the circuit and the operating temperature. Technicians determine the value by measuring the center frequency and dividing it by the bandwidth at the half power points. Calibration involves using a Q meter to verify the performance of individual components before they are combined into a system.
High Q components are essential for stable clock sources and high sensitivity sensors.
Material Impact
Choosing low loss dielectrics and high conductivity metals is the primary way to improve the value. The quality factor is the main metric for evaluating the performance of wireless power transfer coils and antenna systems.
