Millimeter-Wave Reconfigurable Intelligent Surface With Independent and Continuous Amplitude-Phase Control: Unit Cell Design and Circuit Model
Artikel i vetenskaplig tidskrift, 2025

This paper presents a reconfigurable intelligent surface (RIS) unit cell (UC) with independent amplitude-phase control, crucial for complex field shaping in RIS-assisted over-the-air testing. Unlike conventional phase-only tuning UCs, the proposed design enables continuous control from reflective to absorptive states for advanced field synthesis. To quantify reconfigurability, we introduce a generalized complex-plane representation, termed Γ-coverage, mapping both amplitude and phase over all bias states. For the first time at millimeter-wave frequencies, a loop-embedded end-folded UC integrating a forward-biased p-i-n diode and a reverse-biased varactor diode is developed to maximize Γ-coverage. The UC achieves a 0–0.5 amplitude tuning range (equivalent to a controllable loss from complete attenuation to 6 dB) and a −180°–+180° phase tuning range at 28 GHz. The maximum incident angle reaches 45° within ±48° phase fluctuations, extending to 60° with full-phase tuning under a 12 dB loss criterion. We derive empirical circuit models for both diodes to account for high-frequency parasitic effects and formulate a semi-analytical UC equivalent circuit model. The UC prototype is evaluated using a waveguide simulator. The operational bandwidths for reconfigurability are 25.8–28.0 GHz with a relative Γ-coverage area exceeding 25%, and 26.5–27.7 GHz for 360° phase control with 8.4–12 dB losses. The instantaneous bandwidth for stable operation spans 27.3–27.7 GHz, maintaining ±50° phase fluctuations within 5.6–13.4 dB losses. The UC is analyzed in an RIS-assisted near-field plane-wave generation scenario for a compact antenna test range (CATR), achieving high field uniformity (< 0.6 dB and < 2.5° errors). Despite intrinsic UC losses, the RIS-based CATR reduces total system loss by 22.8 dB compared to a far-field test range.

near field

over-the-air testing

Equivalent circuit model

millimeter-wave

reconfigurable intelligent surface

Författare

Yuqing Zhu

Chalmers, Elektroteknik, Kommunikation, Antenner och Optiska Nätverk

Artem Vilenskiy

Emerging Technologies Research Center

Chalmers, Elektroteknik, Kommunikation, Antenner och Optiska Nätverk

Oleg Iupikov

Chalmers, Elektroteknik, Kommunikation, Antenner och Optiska Nätverk

Pavlo Krasov

Chalmers, Elektroteknik, Kommunikation, Antenner och Optiska Nätverk

Thomas Emanuelsson

Ericsson AB

Chalmers, Mikroteknologi och nanovetenskap, Mikrovågselektronik

Gregor Lasser

Chalmers, Mikroteknologi och nanovetenskap, Mikrovågselektronik

Marianna Ivashina

Chalmers, Elektroteknik, Kommunikation, Antenner och Optiska Nätverk

IEEE Transactions on Antennas and Propagation

0018-926X (ISSN) 1558-2221 (eISSN)

Vol. In Press

Ämneskategorier (SSIF 2025)

Annan elektroteknik och elektronik

Telekommunikation

Farkost och rymdteknik

DOI

10.1109/TAP.2025.3577744

Mer information

Senast uppdaterat

2025-06-25