In a joint measurement trial, Rohde & Schwarz and Greenerwave demonstrated that a near-field measurement system can capture the complete radiation pattern of a 50 cm Ku band electronically steerable array (ESA) SATCOM antenna in approximately 30 minutes. The results closely aligned with simulation models within a one-decibel margin, highlighting the approach as a fast, accurate and dependable method for validating antenna performance. For SATCOM manufacturers dealing with the limitations of large testing chambers, the solution offers a more efficient and cost-effective alternative for antenna characterization.
ESA antennas are increasingly becoming critical components in next-generation SATCOM systems, where precise radiation pattern analysis is essential for reliable communication across LEO, MEO and GEO satellite orbits. Traditional far-field testing methods, however, often require extremely large chambers for Ku and Ka band antennas, particularly when testing antennas with apertures of 50 cm or larger. While Compact Antenna Test Ranges (CATR) provide an alternative, they still occupy considerable space and involve lengthy dual-axis positioning processes to accurately map antenna radiation patterns.
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Rohde & Schwarz and Greenerwave have reached a breakthrough in ESA antenna testing in a recent joint measurement trial, achieving highly accurate radiation pattern characterization in the near-field, significantly reducing measurement time. Greenerwave’s innovative SATCOM user terminals are based on reconfigurable intelligent surfaces (RIS), allowing the company to design electronically steerable antennas that deliver high-performance connectivity while reducing energy consumption and reliance on semiconductors compared with conventional solutions.
For the joint measurement campaign, T&M expert Rohde & Schwarz provided its R&S TS8991 over-the-air and antenna measurement system, equipped with a conical cut positioner, and its R&S ZNA vector network analyzer. Together, they evaluated Greenerwave’s passive single-aperture ESA that uses RIS technology for beamforming. The antenna under test (AUT) features a 50 x 50 cm aperture and is designed for low power consumption and easy integration.
The measurement covered an extended upper hemisphere down to a polar angle of 120 degrees, using a one-degree step size. Ten Ku band frequencies were recorded in a total of 32 minutes, thanks to the system’s hardware trigger function. Data was processed using the R&S AMS32 antenna measurement software, which applied a FIAFTA near-field-to-far-field transformation algorithm.
Comparison with the original simulation based on a numerical twin model and with results from Greenerwave’s CATR setup showed peak gain or directivity variations of max. 1 dB and typically 0.3 dB, validating the accuracy of the near-field solution. Export options allow users to continue analysis in tools such as CST Microwave Studio or MATLAB.
The trial shows that even large SATCOM antennas can be characterized quickly and accurately with the R&S TS8991 antenna test system from Rohde & Schwarz in a near-field setup, providing a practical alternative to large-sized far-field chambers or CATRs. This system setup can be used by other SATCOM makers testing broadband, IoT or back haul antennas for applications requiring flexible beam control and high data rates. The setup can be integrated more easily into research lab environments, and it shortens test cycles, reducing overall development cost.
