Because of the different dielectric properties of the nonmetal composite material and its internal damages

a planar capacitive sensor array can be used to achieve visual non-destructive testing.The influence of different excitation modes on testing effect of the internal defects of the composite

aiming at the planar array electrode structure is studied.Three kinds of excitation mode

single

dual and parity excitation are proposed.And their performance differences such as signal strength and detecting depth are analyzed.Compared with single and dual excitation

the results show that signal measurement and imaging quality of the parity excitation are better than the others.The feasibility and effectiveness of planar capacitive sensor array based on capacitance sensitive principle for internal defect detection of composite material are also verified.