Analysis and design of an active lens implemented by planar distributed metamaterials

In this paper, a distributed active lens with PRI/NRI materials is designed and measured. The unit cell of NRI material is analyzed using HFSS under periodic boundary condition to give the dispersion diagram of unit cell. The corresponding refraction index and LH mode frequency computed by circuit model and HFSS are also shown in a good agreement. A scanning arrangement is developed using an Agilent E8364B PNA and an Agilent 85024A active probe to record the S21 values for both the active and passive lenses. The focus and refocus phenomena are observed in the NRI material and the right side PRI material to demonstrate the negative refraction phenomenon. Moreover, the active lens with amplifiers embedded in the transmission path of the NRI material can compensate the imperfect match including dielectric loss, metal loss and impedance mismatch to clearly show the refocusing phenomenon in the right side PRI material.