A two-element antenna array with two same element has been proposed with composite right/left-handed transmission line metamaterials in this paper. Each element is made of three radiating patches, interdigital capacitance between two adjacent 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, substrate and ground plane. The phase difference between two antenna elements is set by adjusting the length of arched microstrip line which is applied to connect two antenna elements. S parameters of the proposed antenna array calculated by finite difference method are in good agreement of measured results. The 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. When antenna array is operated in the zeroth-order resonant frequency, the total physical dimensions are reduced to 0.28 λ0 × 0.10 λ0. Here λ0 is a zeroth-order resonant wavelength.