Fig. 4: Tag preparation, packaging and testing platform.

a Fabrication process of SAW tag; b SAW wafer; c Microscopic view of reflector; d Kovar alloy tag packaging; e Internal structure of SAW tag; f Automated high-temperature experimental platform

a Fabrication process of SAW tag; b SAW wafer; c Microscopic view of reflector; d Kovar alloy tag packaging; e Internal structure of SAW tag; f Automated high-temperature experimental platform