Research on an Improved Metal Surface Defect Detection Sensor Based on a 3D RFID Tag Antenna

Figure 1

Schematic diagram of the meandering slot for the microstrip patch antenna. (a) U-slot current path. (b) L-slot current path. (c) H-slot current path. (d) Rectangular slotted current path.

(a)

(b)

(c)

(d)