A Broadband and FSS-Based Transmitarray Antenna for 5G Millimeter-Wave Applications

This letter describes the design of a broadband and FSS-based transmitarray (TA) antenna for 5G millimeter-wave applications. Two different elements are proposed to avoid the issues of the geometrical parameter resizing of the elements to obtain a 2 bit transmission phase of {-π, -π/2, 0, π/2} to achieve a TA antenna with wideband behaviors. Both of the two proposed elements show low insertion loss of below 1 dB from 24 to 38 GHz. Moreover, the two elements can achieve two sets of discrete transmission phases of {- π, 0} and {-π/2, π/2} without resizing their dimensions, respectively. A TA prototype based on the proposed two elements is designed and fabricated. The measured results agree very well with the simulated ones. The measured 1 and 3 dB gain bandwidth is 28.0-37.5 GHz (29.0%) and 25.1-39.1 GHz (43.7%), respectively. A peak aperture efficiency of 44.7% at 30 GHz is experimentally obtained with a realized gain of 26.1 dBi.