Non-Destructive Testing of Non-Metallic Concentric Pipes Using Microwave Measurements

Recently, non-metallic materials which are resilient-to-corrosion, low cost, and light weight have been exploited in many industrial sectors. A common application of them is in the form of pipes. Due to the fact that the traditional NDT methods are mostly effective for metallic pipes, here, a microwave holographic imaging combined with standardized minimum norm (SMN) is proposed for inspection of multiple concentric non-metallic pipes. To reduce the complexity of the system, we aim at using the narrowest possible frequency band by using an array of receiver antennas. The validity of the proposed imaging method is demonstrated via simulation and experimental results.