Design of a dual-port, side-incident microwave probe for detection of in-pipe damage

Abstract

This study reports on a dual-port, side-incident microwave probe dedicated to the non-destructive inspection of metal pipes. Two types of side-incident probes (LJ and JL) are proposed to emit TM01- and TM02-mode microwaves into the pipe under test, and each type of probe has two ports used to inspect in two opposite directions. Numerical simulations are conducted to study the dimensional parameters affecting the transmission characteristics of the probe and optimize the probe to obtain better mode purity and transmission directivity. The simulation results also suggest that the optimal probe dimensions for one inner pipe diameter can be applied to another diameter by multiplying the dimensions by a factor that is determined by the ratio of two diameters. Two LJ-type, side-incident probes, one with an inner diameter of 19 mm and one of 39 mm, are fabricated according to the simulation results. Experimental verification is subsequently carried out to test the detection directivity of the probes by detecting the short pipes with partially milled damage situated on both sides of both probes. Experimental results show that the proposed dual-port, side-incident probe can effectively detect the in-pipe damage on either side of the probe using the corresponding port and thus realize the directional pipe inspection. Furthermore, this method shows a potential to be applied to various inner pipe diameters.

Design of a simple side-incident TE11 mode microwave probe for nondestructive pipe inspection

“…Figure 5(a) shows that the microwave energy transmitted to the right is obviously more than that to the left when θ = 30 • with proper l E . A further investigation using θ ranging from 20 • to 40 • with 5 • increments illustrates that the ratio of AER In addition, a wide working frequency span, over which the energy ratio is over or around 0.5, is considered ideal for high time-domain resolution [28]. With the above consideration, the values of θ and l E were optimized to 25 • and 18 mm, respectively.…”

“…The diameter of the cable core wire was 0.8 mm, while the inner and outer diameters of the outer metallic layer were 2.2 and 2.9 mm, respectively. The length of the coaxial cable had little influence on the results [28], as only microwaves in the TEM mode propagated inside it and no mode conversion occurred. Its length was set at 50 mm in this study.…”

Metal Surface Defect Detection Method Based on TE01 Mode Microwave

“…Katagiri T et al analyzed the TEM-mode/TE01-mode conversion, and the microwave reflection was related to the transmission frequency, the size of the transmission line, the electromagnetic properties, and the roughness of the material surface [16][17][18]. Chen G et al designed two TEM-TM01 and TEM-TM02 incident probes to obtain better propagation mode purity and propagation directionality, detect defects in different orientations, and analyze the influence of propagation mode conversion at bends on detection signals [19][20][21][22]. YU YT et al established a finite integral numerical model to analyze the relationship between the reflection coefficient phase and the defect edge position [23].…”