To overcome the limitation that the linear transverse dimension of microstrip antenna is of the order of half wavelength, a two-element antenna array has been proposed with composite right/left-handed transmission line metamaterials in this paper. The antenna array is made of two same antenna elements. Each element consists of three radiating patches, interdigital capacitance between two radiation patches and shorted pin connecting radiating patch with ground plane. Therefore, a composite right/left-handed transmission line metamaterials is constituted by radiating patch, shorted pin, antenna of substrate and ground plane. An arched microstrip line is used to connect two antenna elements. The phase difference between two antenna elements is set by adjusting the length of arched microstrip line. S parameters of antenna array obtained by numerical computation are in good agreement of that obtained by measurement. Meanwhile, zeroth-order resonant frequency of two-element antenna array is consistent with that estimated by the circuit theory with extracting equivalent circuit parameters of composite right/left-handed transmission line metamaterials. The peak gain of this antenna array is 6.3dB. Seen from this point, the antenna peak gain is enhanced. When operating in the zeroth-order resonant frequency, physical dimensions of this antenna element are reduced to 0.28λ0×0.1λ0. Here λ0 is a zeroth-order resonant wavelength. The proposed antenna array is a novel venue for antenna miniaturization.