Fraunhofer Institute for High Frequency Physics and Radar Techniques FHRThe angular coverage of phased-array antennas is inherently limited by physical constraints. In the long term, electronically tunable metamaterials may offer a means to extend this range. Researchers at Fraunhofer FHR are investigating this approach both experimentally and through prototypical demonstrators. The objective is to establish the foundations for high‑performance, yet compact and adaptable antenna systems that can be integrated into current and future applications.
A central question is the extent to which such tunable metamaterials can influence the phase of radar radiation, and what level of losses is introduced in the process. Researchers at our institute have addressed these questions through systematic measurements on experimental setups and prototypes. To this end, they fabricated and characterized two large metamaterial printed circuit boards, each measuring 24 by 16 centimeters. In an initial experiment, the boards were mounted in front of a transmitting antenna, and the radiation pattern was analyzed using a receiving antenna. The measurements demonstrated a high effectiveness of the metamaterials: for both horizontal and vertical polarization, phase shifts of up to 170 degrees were achieved. Losses were also low, amounting to only one to two decibels.
Extended scan range with compact design
Building on these results, the Fraunhofer FHR team developed two demonstrator prototypes. The first consists of a single tunable metamaterial panel illuminated by an antenna element, while the second arranges multiple panels in a faceted configuration in front of a curved antenna array. For the first prototype, the researchers demonstrated phase compensation enabling beam focusing and lens‑like beam shaping, as well as phase compensation for beam steering. For both vertical and horizontal polarization, a scan range of ±60 degrees was achieved, accompanied by an increase in antenna gain of three decibels.
These findings are particularly relevant for platform‑constrained applications, such as unmanned aerial systems, where weight and space limitations preclude the use of large phased arrays. Tunable metamaterials offer a pathway to compact, cost‑efficient antenna systems without sacrificing enhanced radiation characteristics.
The second prototype also proved effective: within an azimuthal scan range of 70 to 90 degrees, the antenna gain was improved by one to two decibels. This underscores the potential of tunable metamaterials for realistic array geometries and application‑oriented system architectures, forming a basis for further joint development and adaptation efforts with industrial and institutional partners.
