New antenna designs could pave the way for advanced 6G satellite networks
Simon Mansfield
Sydney, Australia (SPX) August 22, 2024
A research team from Beijing Institute of Technology has presented an innovative design methodology for active multi-beam antennas that could become a key component of future 6G satellite networks. The new approach aims to address critical limitations of traditional multi-beam antenna technology, especially in meeting the demanding requirements of Very High Throughput Satellite (VHTS) systems.
Traditional multi-beam antennas in VHTS systems are used to provide wide-area coverage, usually operating in Ka-band and employing a seven-color frequency reuse scheme covering more than 500 beams. However, current antenna technologies, namely multi-aperture antennas and passive multi-feed multi-beam antennas, have significant performance issues when performing the task of covering a large area. Multi-aperture antennas, which often use three to four reflector antennas, suffer from poor beam gain at the edges, beam deformation, and increased sidelobes. Conversely, passive multi-feed systems, which rely on waveguide beamforming structures, become overly complex and difficult to manage when the number of feeds exceeds 500, a common requirement in large-scale satellite engineering.
To address these challenges, active multi-feed antennas have been introduced, which are widely implemented on mobile communication satellites. These antennas use large mesh reflectors combined with multi-feed arrays to achieve high levels of overlap of sub-beams and optimize both beam gain and sidelobes through comprehensive array synthesis. However, the 12-color frequency reuse scheme used in these systems results in a carrier-to-interference (C/I) ratio of approximately 12 dB, which is insufficient for VHTS applications that require a C/I ratio of 15 dB using a 7-color frequency reuse scheme. Furthermore, as the number of beams required increases, the complexity of the beamforming network increases dramatically.
To solve these problems, the research team proposed a new design methodology that incorporates multi-target cooperation and a multi-feed amplitude and phase weighted optimization algorithm. The approach optimizes the feed amplitude and phase excitation coefficients and establishes an objective function based on the number of feeds, the gain of the composite beam, and the required C/I ratio. The method also includes the use of an artificial intelligence (AI)-based convolutional autoencoder surrogate model to efficiently find the optimal beam excitation coefficients, thereby significantly accelerating the optimization process.
The proposed method consists of an eight-step process that first analyzes key beam parameters using the GRASP model. The researchers then build and train a convolutional autoencoder model to identify and utilize nonlinear parameters in the optimization. They iteratively tune these parameters using a max-min algorithm, and finally validate the optimized beam pattern using the GRASP model.
The designed active multi-beam antenna showed excellent performance when applied to the technical requirements of VHTS in simulations. It achieved ultra-high gain of over 50 dBi and C/I ratio of over 18 dB while covering about 1,000 beams. These results indicate that this antenna design can support Terabit per second (Tbps)-level communication capacity, making it a promising solution for next-generation satellite networks.
Research Report: Design Methodology for Active Multibeam Antennas and Their Application to Future 6G Satellite Networks
Related Links
Beijing Institute of Technology
Space Technology News – Applications and Research
