A high efficiency (>64%),broadband terahertz (THz) polarization converter is designed by employing a dielectric metamaterial made from high-impedance silicon.The working principle can be related to that of a traditional half waveplate.More interesting,such a dielectric metamaterial can a lso be applied in controlling the output phase of the cross-polarized wave.On the basis of such a device,8di fferent dielectric structure unit cells are selected from numerous simulations for realizing the phase control.By prope rly engineering the spatial arrangement of these unit cells to form a linear phase profile at the interface, a high efficiency,broadband terahertz anomalous deflector is further designed.The effective working frequency range c overs 0.75THz to 1.25THz with the highest deflection efficiency of more than 70% at 1.25THz,which is much stronge r than that of its metallic single-layer metamaterial counterpart (10%).Meanwhile,the deflection angle is strongly related to the frequency, obeying the generalized Snell′s law.To experimentally characterize the propose d device,an angle-resolved,fiber- based terahertz time-domain spectrometer is employed.The experimental results show a good agreement with the simulation and theoretical prediction.Such dielectric metamaterials overcome th e intrinsic ohmic loss problem of conventional metallic metamaterials,and are also very easy to design and fabric ate.