This　paper　presents　a　THz　monolithic　antenna　implementation　based　on　the　left-handed　coupled-line　(LH　CL).　The　theoretical　dispersion　curves　extracted　by　the　scattering　parameters　show　that　the　odd-mode　normalized　attenuation　alpha　odd/beta(0))　of　the　left-handed　coupled-line　in　the　leakage　region　(　beta(odd)/beta(0)＜1)　is　higher　than　that　of　the　single　left-handed　transmission　line　in　the　leakage　region　(　beta/beta(0)＜1),　indicating　the　high　potential　on　miniaturized　antenna　design.　An　antenna　prototype,　including　the　on-chip　matching　network,　is　designed　based　on　the　dispersion　curve,　and　fabricated　by　the　standard　mu　m　1P8M　CMOS　technology.　The　measured　return-loss　of　the　prototype　is　less　than　-13　dB　at　422　GHz,　The　simulated　antenna　gain　is　about　2.6　dBi　at　420　GHz.