## 1 Introduction
[PERSON] adopted a pair of 45\({}^{\circ}\) parallelogram coils in the experiments to test the carbon fiber-reinforced polymer (CFRP) with low electrical conductivity, and was capable of clearly detecting the slightest side cuts (0.2 times the width) and fiber fractures. The experiments demonstrated an excellent signal-to-noise ratio [7]. For the detection of curved pipes with natural concave defects, [PERSON], [PERSON] put forward a transmitter-receiver flexible printed coil (FPC) array employing the Wireless Power Transfer (WPT) method. An experimental study was carried out on the material surface using a single excitation coil and multiple receiving coils based on the WPT principle. The experiment utilized 21 scanning points to measure the depressions on the dedicated concave samples. The experimental data were used for training and evaluating the dual resonance response. Feature selection and feature fusion were conducted through deep learning to map and reconstruct the defective depressions for quantitative nondestructive testing [8]. [PERSON] et al. designed and fabricated a rectangular planar inductive coil with a wire diameter that could be reduced to 10 um. Subsequently, they carried out a simulation analysis of the magnetic field surrounding the coil with the aid of FEM software (ANSYS(r) version 12.1). Eventually, they successfully utilized this coil to capture and manipulate magnetic particles [9]. To overcome the lift-off effect that occurs during magnetic field measurement, [PERSON] et al. designed a probe composed of an \"8\"-shaped transmitting coil and a circular receiving coil. This probe is not only insensitive to the variation in lift-off distance but also exhibits a high degree of sensitivity when detecting defects. In the quantitative experimental tests for planar wave detection and crack detection, the scanning images clearly display the cracks, and the length and location of the cracks can be estimated from the scanning images [10]. [PERSON] et al. put forward the method of pulsed eddy current thermal imaging for detecting low-frequency defects in carbon fiber-reinforced plastics. By utilizing eddy current loss to characterize the thermal power of eddy currents in carbon fiber-reinforced plastics, detection results with a frequency of up to 750 kHz can be provided [11]. The special conductive principle of CFRP makes the design scheme of the related probe required for its eddy current testing one of the research hotspots. [PERSON] et al. devised a coil group in which the excitation coil and the receiving coil are mutually quadrupolar for the purpose of reducing the influence of the excitation magnetic field on the detection coil. This probe can be utilized for detecting the external waviness of CFRP plates [12]. [PERSON], [PERSON] et al. guided Lamb wave tomography and eddy current testing (ECT) techniques were combined to locate and evaluate fiber breaks in carbon fiber-reinforced plastic (CFRP) structures. Guided wave testing (GWT) and computed tomography (CT) imaging were employed to quickly locate fiber breaks in the CFRP plate [13]. [PERSON] et al. proposed a self-resonance ECT method for non-contact detection of CFRP and developed an ECT system capable of detecting CFRP defects at low frequencies while maintaining a relatively high signal-to-noise ratio. The results indicate that the detection effect of the self-resonance ECT system at 500 kHz is similar to that at low frequencies. In comparison with the performance of traditional ECT systems at 10 MHz, a frequency of 500 kHz is sufficient to provide satisfactory detection results for the aforementioned CFRP samples [14]. Based on the above background, the eddy current nondestructive testing technology for CFRP is mainly employed for defect detection, while studies on the carbon fiber areal density of CFRP prepre are limited.