An antenna array consists of multiple radiating elements with certain separation distances between them. Conventionally, the radiating elements are identical so that the radiations of all elements are summed up to form the total radiation pattern of the array. The antenna array exhibits a large radiating area, thus high directivity. According to the position, amplitude, and phase excitation of each radiating element, the total radiation pattern of the array can be synthesized. Among all directive antennas, the antenna array provides beamforming and beam steering ability besides the high directivity. IHF institute has participated in many industrial and research projects designing the antenna arrays for radar and wireless communication systems, such as SBDist and GeReLEO projects funded by the German Federal Ministry of Education and Research.
In the SBDist project, a module with low latency, high data rate, and a robust wireless communication system is designed to communicate between two trains . The antenna array of this module consists of 4x4 sequentially rotated circularly polarized patch antennas operating at 60 GHz . The high directive antenna array concentrates the transmitted power towards the SBDist model on the other train, avoiding interference and reflection from unwanted directions . SBDist — KIS Website (forschung-it-sicherheit-kommunikationssysteme.de)
The GeReLEO-SMART project aims to develop a relay communication system that connects the satellites at LEO orbit with a ground station. In this project, , an active antenna array that contains an embedded RF bandpass filter and LNA is designed at the IHF institute [4, 5]. This is an example of the active antenna arrays intended to fulfil the space application requirements such as high gain and immunity to the co-existence of other communication systems on the same payload. Institute of High Frequency Technology | GeReLEO-SMART (rwth-aachen.de)
 Sattiraju, R., et al. Design of a highly reliable wireless module for ultra-low-latency short range applications. in 2017 IEEE 13th International Workshop on Factory Communication Systems (WFCS). 2017
 Al-Bassam, A., W. Alshrafi, and D. Heberling. A 60 GHz circularly polarized antenna array for line-of-sight train-to-train communication. in 2018 11th German Microwave Conference (GeMiC). 2018
 Soliman, M., et al., Automatic Train Coupling: Challenges and Key Enablers. IEEE Communications Magazine, 2019. 57(9): p. 32-38
 Alshrafi, W., et al. Multi feed active antenna at Ka-band for satellite communications. in The Loughborough Antennas & Propagation Conference (LAPC 2018). 2018
 Alshrafi, W., R. Wilke, and D. Heberling. Multi layer planar Ka-band satellite receive antenna with integrated LNA. in 2017 International Symposium on Antennas and Propagation (ISAP). 2017