Miniature Slotted-Folded-Patch Antenna for OnMetal UHF Tag

A simple folded patch antenna is proposed to be used as a metal mountable UHF tag antenna. Two parallel slots are introduced on the radiating patch for increasing its electrical length, causing this antenna to have a small size of 35 × 35 × 1.6 mm
³
(0.107λ × 0.107λ × 0.005λ). Antenna's input impedance can be easily matched to the complex conjugate of the chip's impedance by varying the stub's width and position. Fabrication of the tag antenna by using flexible foam as a substrate permits the application of this tag antenna on curved metallic surfaces. The maximum achievable read distance of the tag antenna is ~9.5 m at resonant frequency of 915 MHz.