were designed to explore the factors that affect the ( 0.3)(W h0.264) resonant frequency. Strain measurement was (3) achieved by bonding the antenna to a cantilever beam and applying loads at the free end of the canti-Assuming that the antenna is subjected to a ten-lever beam, and microstrip antenna sensors that can sile strain ε along its electrical length direction, detect the crack length and propagtion alng diffr-the patch width and the su bstrate thickness will ent orientation with a sub-millimeter