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.