Dual-band dynamic reconfigurable intelligent surface for signal enhancement in millimeter wave

Millimeter wave with large bandwidth, high transmission rate, and low delay is considered a reliable alternative to cope with the spectrum shortage. However, the fast attenuation and narrow beam characteristics make it difficult to achieve long-distance or wide-range applications. Here, a 1-bit dual-band reflective reconfigurable intelligent surface (RIS) for signal enhancement in millimeter wave with 16×16 elements is designed, fabricated, and measured. Different from most existent RIS, dynamic programming is realized at two separate frequency bands by integrating the PIN diodes and field-programmable gate array (FPGA). Particularly, the beam deflection, dual-beam, and multi-beam are created based on the coding theory and convolution operation, proving the effectiveness of wavefront manipulation. Moreover, the far-field patterns and signal power with different coding sequences are measured and compared. It is indicated that the received signal power is 6–7 dB stronger than that without coding, which shows good agreement with the desired expectations. The proposed reconfigurable metasurface exhibits great potential in beam forming, making it a promising candidate for progressive wireless communication applications.