A Linear Seismometer Using Octagonal Microwave Sensor Based on Inverted Pendulum Structure for Earthquake Detection

In this article, a novel method for measuring acceleration is developed by integrating microwave displacement sensor and inverted pendulum structure for earthquake detection. The resonance frequency of the structure is designed to be operated as an accelerometer suitable for seismic sensing. Furthermore, an octagonal split ring resonator (SRR) operated at a fixed frequency with enhanced linearity and dynamic range is proposed as the displacement sensor. When vibrations are applied to the structure, acceleration can be detected by displacement of the pendulum, and the relative motion of the pendulum can be sensed due to the variation in the transmission coefficient at resonance. The experimental results demonstrate a consistent linear relationship between the sensor voltage and the input accelerations under three different frequencies, and the proposed device is proved to be suitable for earthquake detection with vibration frequencies up to 20 Hz and vibration accelerations from 60 cm/s² to 500 cm/s².