- Reconfigurable intelligent surfaces (RIS) are drawing attention in the wireless industry due to their potential for an efficient 5G mmWave rollout as well as future 6G applications.
- A measurement campaign by Rohde & Schwarz and Greenerwave recently characterized the configurable radio wave reflection properties of a novel FR2 RIS module developed by Greenerwave with an over-the-air (OTA) antenna test system from Rohde & Schwarz.
- These measurements confirmed that a metamaterial-based RIS can improve the coverage and efficiency of wireless communications performance, especially for 5G FR2.
Reconfigurable intelligent surfaces (RIS) promise to revolutionize wireless communications. RIS is a key technology for 6G networks, which must be more efficient than 4G LTE or 5G NR in every way. RIS technology uses metamaterials to control the otherwise random radio environment. Metamaterials are the key to fulfilling the promise of RIS. The materials enable control over EM waves by manipulating the impedance on a subwavelength scale and have led to significant breakthroughs in imaging, radar and wireless communications.
Rohde & Schwarz test and measurement instruments were used to characterize an FR2 RIS from Greenerwave for the recent test campaign. Testing RIS modules requires a test environment that can be illuminated from different incident angles while simultaneously measuring signals at multiple angles. A wireless performance test chamber (WPTC) from Rohde & Schwarz was used for over-the-air (OTA) measurements. A holder was specifically designed for the feed antenna illuminating the Greenerwave RIS.
The RIS from Greenerwave uses a metamaterial proprietary technology. The RIS is an electronic device, composed of many layers and a surface inlaid with a set of patch antennas, called pixels or unit cells, whose electromagnetic responses can be controlled via a control board. The module operates in 5G FR2 and beyond, covering a bandwidth of 25-30 GHz with instantaneous bandwidth of 2 GHz. The module comes with separate polarization control, beam scanning from -60 to 60 degrees and a beam width as narrow as 3 degrees.
During the measurement campaigns, the RIS reflection characteristics and reflection quality were investigated in the test chamber with respect to modulated 5G signals in the millimeterwave frequency range. The 3D reflection characteristic measurements were performed with the R&S ZVA vector network analyzer (VNA), and the 5G signal reflection quality measurements used the R&S SMW200A vector signal generator and R&S FSW signal and spectrum analyzer. R&S AMS32 software was used to automate measurement and data analysis. Results verified that the Greenerwave RIS can enhance wireless communications capabilities, particularly in the context of 5G FR2 implementations.