Precise diameter measurement of reinforcing bar and steel pipe based on bi-static model using microwave radar

In this report, a novel signal processing method for microwave radar is considered, in order to realize precise diameter measurement of the reinforcing bars and the steel pipes in the concrete structures. Particularly, a geometric analysis which is considering the bi-static antenna configuration for the microwave propagation paths is introduced, and a diameter of the buried circular target object has been tried to measure precisely. In the proposed geometric analysis, the accurate microwave propagation length, or the accurate propagation time estimation is necessary for precise diameter measurement. Then, the improved cross-correlation envelope curve method is newly proposed, and superior propagation time estimation accuracy over the sampling interval has been accomplished. Finally, an effectiveness of the proposed methods has been confirmed experimentally, by applying them to the diameter measurement of the steel pipe in the air. Their experimental results show that the proposed methods have certain advanced performances for a precise diameter measurement.