This　paper　presents　a　compact　circularly　polarized　microstrip　antenna　for　radio　frequency　identification　(RFID)　readers.　The　dimensions　of　the　proposed　antenna　are　reduced　by　etching　a　cross　slot　in　the　radiation　patch　and　loading　four　grounded　coupling　patches　on　the　four　corners　of　the　radiation　patch.　An　inverted　Z-shaped　coupling　feedline　is　used　to　realize　circularly　polarized　operation.　The　measured　-10　dB　$\vert　\text{S}_{11}\vert　$　bandwidth,　3-dB　axial　ratio　bandwidth　and　maximum　gain　are　872-1095　MHz,　888-933　MHz,　and　5.52　dBi,　respectively,　at　922　MHz　frequency.　The　overall　dimension　of　the　proposed　antenna　is　.36\,\,\lambda　_{\mathrm　{g}}　\times　0.36\,\,\lambda　_{\mathrm　{g}}　\times　0.05\,\,\lambda　_{\mathrm　{g}}$　(　$\lambda　_{\mathrm　{g}}$　is　the　guide　wavelength　at　the　center　frequency　of　915　MHz).　The　proposed　antenna　has　small　size　with　good　overall　performance　and　is　suitable　for　compact　RFID　devices.　©　2013　IEEE.