Based　on　the　Planar　Inverted　F-shaped　Antenna　structure,　we　propose　a　two-side　anti-metal　tag　antenna　for　ultra-high　frequency　radio　frequency　identification.　The　chip　of　the　proposed　tag　antenna　is　housed　within　a　square　slot　of　FR4　material.　Three　gaps　can　be　observed　on　the　surface　of　the　proposed　tag　antenna.　As　a　result　of　these　gaps,　the　resonant　frequency　can　be　adjusted　with　flexibility　in　order　to　ensure　an　optimal　power　transmission　coefficient　and　impedance　matching.　The　proposed　tag　antenna　maintains　a　compact　size　of　40×　28×　3.2　mm3.　The　proposed　tag　antenna　is　measured　by　placing　it　on　a　metal　plate,　resulting　in　5.2　m　and　5　m　read　distances,　respectively.　The　proposed　tag　antenna　is　compact,　and　exhibits　good　performance,　particularly　with　its　two-side　anti-metal　characteristics.　　©　2023　IEEE.