Dual-band multi-bit programmable reflective metasurface unit cell: design and experiment

Abstract

Programmable reflective metasurfaces that combine the features of reconfigurable phased array antennas and reflectors are an effective solution for radar and modern communication systems. However, most of the demonstrated active metasurfaces support tunable responses for a specific frequency band. Thus, we propose a programmable metasurface that combines the advantages of multi-bit phase quantization and dual-band operations. To actively control the diverse functions, two PIN diodes are integrated on the radiating element, and these diodes are controlled by the biasing voltage. The unit cell is fabricated, and experimental characterization is performed in the waveguide measurement setup. The proposed design can be applied for imaging and high-capacity wireless communications.

Miniaturized square fractal ring patch unit cell for active reflective metasurface in C‐ and X‐bands

“…First, the complexities of the bias circuit and the control sequence are lower than those of meta-patterns utilizing 10 8 and two PIN diodes. 17 Second, it can be clearly found that our unit cell has another advantage from the perspective of the size reduction compared with those of double-layer meta-patterns 8 and reflectarray based on a rectangular patch. 13 Besides, a ratio of the second frequency to the first one of the proposed unit cell is much larger than that of the rectangular patch 13 utilizing the same number of the PIN diode.…”

“…Table 1 compares the proposed reflective metasurface unit cell with other dual‐band cases utilizing PIN diodes. First, the complexities of the bias circuit and the control sequence are lower than those of meta‐patterns utilizing 10 8 and two PIN diodes 17 . Second, it can be clearly found that our unit cell has another advantage from the perspective of the size reduction compared with those of double‐layer meta‐patterns 8 and reflectarray based on a rectangular patch 13 .…”

“…It can be clearly confirmed by comparing the calculated errors with the permitted error ranges of ±22.5% for the reflectarray based on the rectangular patch, 13 ±20% for the double-layer meta-patterns, 8 and ±15% for the metapattern utilizing two PIN diodes. 17 To verify the accuracy of the design, the same structure is solved using another commercial FEM solver, Ansys HFSS, and the results are compared with those calculated by the Comsol Multiphysics. As shown in Figure 2, both results are well-matched for the phase responses.…”

“…Besides, the active switching between on or off states of the PIN diode has been utilized in a single band. 12,14 Even though some cases have been reported that utilize the PIN diode for dual-band phase controls, 8,13,17 there exist limitations that the size of the unit cells is relatively large, 13 or copper patches of the unit cells are connected 8 or closely located 17 with those of the adjacent cells. Besides, the number of PIN diodes of more than one 8,17 may increase the complexities of the bias circuits and their control sequences.…”

“…12,14 Even though some cases have been reported that utilize the PIN diode for dual-band phase controls, 8,13,17 there exist limitations that the size of the unit cells is relatively large, 13 or copper patches of the unit cells are connected 8 or closely located 17 with those of the adjacent cells. Besides, the number of PIN diodes of more than one 8,17 may increase the complexities of the bias circuits and their control sequences. Because the size of the unit cell determines the resolution of the quantized phase distribution, miniaturization of the unit cell is one of the key issues to guarantee the accuracy of the beam steering.…”