An Efficient Approach for Designing Ultrathin Transmitarray Antennas Based on Equivalent Circuit Analysis

• Published in: IEEE transactions on antennas and propagation Vol. 72; no. 7; pp. 5810 - 5821
• Main Authors: Nguyen, Binh Duong, Nguyen, Minh Thien, Van, Vien
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anisotropic; Antenna; Antennas; Bandwidths; Equivalent circuits; Gain; Impedance; Incident waves; Integrated circuit modeling; Substrates; Thickness; transmitarray; Transmitting antennas; ultrathin; Unit cell; wideband
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2024.3412235

We present an ultrathin and wideband transmitarray antenna formed from unit-cells with an ultralow thickness of <inline-formula> <tex-math notation="LaTeX">0.04 \lambda _{0} </tex-math></inline-formula>. The unit-cells are constructed from two identical substrates with three metallic layers to provide a 90° polarization rotation of the incident wave. An efficient and simple way to design the low thickness unit-cell is presented based on the analysis of its equivalent circuit (EQC). To demonstrate the method, we designed and optimized unit-cells operating at center frequency of 12 GHz to provide a 3-bit phase resolution with eight phase states. Full-wave simulation results demonstrate that eight phase states have a large common 1 dB transmission magnitude bandwidth of 27%. A transmitarray prototype using the 3-bit phase shift unit cells was also fabricated. Measurements show that the transmitarray achieves a high aperture efficiency of 62% and a large 1 dB gain bandwidth of 22%.