A Double-Layer Wideband Transmitarray Antenna Using Two Degrees of Freedom Elements Around 20 GHz

A double-layer wideband transmitarray antenna using two degrees of freedom (TDF) elements is presented. The double-layer transmitarray antenna is composed of 441 elements. Each element includes four metal vias and two patches with TDF printed on both sides of the dielectric substrate. Four metal vias are used to achieve the maximum transmission magnitude and two patches with TDF are adopted to obtain a sufficiently large variation range of phase shift. A square transmittarray is designed, fabricated, and measured to validate the proposed design. The simulation and measurement results have a good agreement. The experimental results show that the proposed antenna has a high gain of 30.0 dBi at 21 GHz, aperture efficiency of 40% and 1 dB gain bandwidth of 9.6% (20.1-22.2 GHz). The proposed doublelayer transmittarray antenna greatly simplifies the design complexity and reduces the thickness, mass, and cost with respect to existing transmitarray antennas.