Accurate Representation of the Rolling Motion for the Self-Rolled-Up Inductor with Radar Interferometry

A novel radar interferometry technique is proposed to assess the dynamic rolling motion process for the self-rolled-up inductor made of SiNx nanomembrane. The rolling nanomembrane has an extremely small radar cross section (RCS) of < -76.5 dBsm. The self-rolled-up displacement motion of < 150 μm needs to be obtained to assess the inductor efficacy. However, the I/Q imbalance and low signal to noise ratio (SNR) make it highly challenging to accurately measure such weak motion signals. A channels pre-calibration and moving average filtering (CCMAF) technique is proposed to extract the I/Q imbalance parameters and imitate zero-mean noise, which allows the 24 GHz radar interferometry to precisely detect the rolling motion. Simulations show the error of the estimated mismatch coefficients using the proposed technique is only 0.04%. Experimental results depict that the root mean square error (RMSE) of the measured self-rolled-up motion is lowered by 15.4% with 2.3 dB SNR improvement.