Development of an integrated photonic beamformer for electronically-steered K<inf>u</inf>-band phased array antenna

Abstract

Currently an integrated photonic beamformer for electronically-steered K u -band phased array antenna (PAA) system for satellite communications is being developed within a Dutch Point One R&D Innovation Project “Broadband Satellite Communication Services on High-Speed Transport Vehicles”, targeting instantaneous reception of the full K u -band (10.7–12.75 GHz), squint-free and seamless beam steering, and polarization agility. The use of integrated photonic beamformer enables an antenna system with multi-gigahertz instantaneous bandwidth, compact form factor, light weight, and large beam scanning range, which are challenging requirements for beamformers using only electronics-based RF technologies. An important aspect tackled in this project is to reduce the system cost such that it is commercially suitable for civil purposes in mobile satellite communications, particularly in aeronautic/avionic satellite communications where a low profile and light weight are essential requirements for the antenna system. The core of the photonic beamformer consists of an optical ring resonator (ORR) filter-based beamforming network (BFN). ORR filters are capable to provide continuously tunable true time delays (TTDs) with configurable bandwidth, and serve as delay elements in a BFN allowing squint-free and seamless beam steering for gigahertz bandwidth applications [1], [2]. Therefore, this approach is superior to the BFNs using phase shifters, discrete time delays or digital BFNs. This photonic beamformer also features optical single-sideband suppressed-carrier modulation and coherent optical detection techniques, resulting in reduced number of ORRs in the BFN [1], [2]. Other system components such as the optical sideband filter, optical signal combining and carrier reinsertion circuitry are integrated with the ORRs in one photonic BFN chip. In the past, a laboratory demonstrator of such an antenna system has been realized as a proof-of-concept, incorporating individually packaged components, such as LNBs and optical modulators [2]. Currently, there is a large effort in the development of the key components, namely front-end, optical modulator, and photonic BFN, and the integration between them, aiming for the actual deployment of the antenna system.