A wideband low RCS and high gain phase gradient metalens antenna

A wideband low RCS but high gain phase gradient metalens antenna (PGMA) is proposed in this paper. The proposed PGMA is comprised of 3 layers of phase gradient metasurface (PGM) as inhomogeneous special metalens structure (PGML) which are fed by a linearly polarized patch antenna. The PGML’s ability to transform radiated spherical waves from focal point to transmitted plane waves and manipulate reflected waves due to normal incident plane waves leads to simultaneously high gain and low RCS PGMA in a wide impedance frequency bandwidth of 9.31 to 10.16 GHz. Simulation results of the proposed PGMA show that in band average values of 18.7 dB, 15.3 dB, and 10.5 dB are achieved for gain, RCS reductions (RCSR) for co– and cross-polarizations, respectively. A prototype of the PGMA is fabricated and measured. A −3dB gain bandwidth of 12.2% is achieved. Additionally, peak gain, RCSR, and RCS values of 19 dB, 18 dB, and −11.1 dBsm, are obtained respectively at the operating frequency of 9.8 GHz. Moreover, ultrawideband RCSR from 1 to 20 GHz are achieved for co– and cross-polarizations. Measurements show excellent agreement with simulations.