Wideband Low-Profile Ku-Band Transmitarray Antenna

A wideband, low profile transmitarray antenna (TA) operating in Ku-band (12GHz-18GHz) is proposed. The transmitarray antenna is composed of aperiodic transmitarray units arranged periodically. The TA unit is mainly composed of three layers, which are composed of metals and substrates. Square patches are printed on the substrate of the top and bottom layers, and the middle layer is a Jerusalem slot in the ground. The overall thickness of TA unit is 0.165λ
₀
(λ
₀
is the free space wavelength at 15GHz). In Ku-band, the insertion of the TA unit is less than 0.5dB, which reduces the backward radiation of the transmitarray antenna. The 360° phase is achieved by changing the length of the patch and slot, and the proposed transmitarray unit has a flat phase curve and great transmission characteristics. In order to verify the proposed design, a transmitarray antenna with 351 TA units operating at 15GHz is fabricated and measured. The measurement results show that the TA can achieve a 37.3% (14.4GHz-20GHz) 1-dB gain bandwidth, the measurement gain is 23.06dBi with 42.3% aperture efficiency at 15GHz, and the backward radiation level is below -15dB. The designed TA unit has symmetrical structure, so the transmitarray antenna can work in dual linear polarization or dual circular polarization.