Investigation on the beam-scanning capability of a gradient index fishnet structure

In this work the beam-scanning capability of a gradient index fishnet array, which is designed to operate at 22.5 GHz, is investigated. The results are discussed based on unit cell simulations and far-field measurements. The gradient is realized by changing the permittivity of a dielectric layer in each unit cell element resulting a tuning of the magnetic resonance frequency. Hence, an effective differential refractive index of 3.8 is achieved at 22.5 GHz yielding a theoretical beam-scanning angle of ±6.6°. Farfield measurements of a 5×5 array confirm the beam-scanning capability with a beam-scanning angle of ±3°. The deviation of the measured results is discussed.