Partially　reflecting　surface　(PRS)　resonant　antennas　have　attracted　significant　attention　for　the　past　two　decades.　However,　how　to　improve　their　peak　gain　is　still　a　challenge.　This　article　proposes　a　nonresonant　PRS　antenna　that　does　not　require　the　conventional　resonant　condition　that　limits　design　flexibility　and　peak　gain.　It　consists　of　a　PRS,　a　ground,　a　small　feed,　and　a　transparent　phase-correcting　surface　(PCS)　placed　above　the　PRS　for　phase　compensation.　The　ray-tracing　method　is　used　to　analyze　the　proposed　nonresonant　PRS　antenna,　and　numerical　simulations　are　conducted　to　verify　its　effectiveness.　Our　theoretical　and　numerical　results　show　that　the　gain　of　a　PRS　antenna　with　a　nonresonant　cavity　reaches　its　peak　when　the　cavity　height　is　between　0.6　lambda　and　0.9　lambda　.　Three　prototypes　are　fabricated　and　tested,　and　the　measured　results　show　that　peak　gains　of　over　25　dBi　and　3　dB　gain　bandwidths　of　more　than　10%　can　be　achieved　at　the　same　time.