Spin wave linewidth measurement of microwave ferrite materials using rectangular resonant cavity with adjustable frequency

• Microwave source works at fixed frequency and an adjustable rectangular cavity is employed.
• An adjustable high-power attenuator and an isolator simplify the system.
• Frequencies of the cavity loaded with different samples can be adjusted to the same value with the frequency of the microwave source.
• The new test system can measure spin wave linewidth of 1–35 Oe.

The traditional method to measure the spin wave linewidth of ferrite material uses a high-power microwave source with adjustable frequency and a rectangular cavity with fixed frequency. However, the microwave source with adjustable is more expensive and inaccurate. In this paper, we propose a new and economic method to tackle these problems. A microwave source with a fixed frequency instead of the adjustable one and an adjustable cavity are employed. The resonant frequencies of the cavity loaded with different samples are adjusted to the same value with the frequency of the microwave source. This means the proposed system has better performance in terms of accuracy and operation. Besides, an adjustable high-power attenuator and an isolator are employed to replace the power divider and high-power termination in other systems, which makes the operation more convenient. Experiments verify that a wider linewidth ranging from 1–35 Oe can be measured accurately and the uncertainty of the linewidth can be estimated within ±15%.