Intern in the Electrical Department - Antenna and Sub-millimetre Waves Section

## Location ESTEC, Noordwijk, Netherlands ## Our team and mission The Antennas and Sub-millimetre Waves Section provides functional support to ESA projects across all the various domains (Navigation, Earth Observation, Telecommunication/Secure Connectivity, Human Robotic Exploration and Launchers) and carries out technological research (R&D) in the field(s) of space antenna systems, submillimetre wave instruments and associated technologies. ## The Antennas and Sub-millimetre Waves Section covers - analysis, engineering, RF modelling and design tool developments of stand-alone antennas (ground and space) as well as interference effects among antennas and with the spacecraft structure or other platform (like aircraft/train/vehicle); - design and analysis of all antenna (active and passive) sub-systems including e.g., stand-alone radiators, arrays, reflector, lens optics, dichroics and their associated focal plane; - analysis, engineering, RF modelling and design tool developments of instrument architecture, antenna, front-end technology and components for sub-millimetre wave applications; - antenna measurements and RF material characterisation.

Candidates interested are encouraged to visit the ESA website: http://www.esa.int ## 1) Topic 1: Assessment of Error Sources and Calibration Techniques in Active Phased Arrays Calibration is a key element in the operation of active phased array antennas.

Small amplitude and phase errors caused by component tolerances, thermal effects, and ageing can significantly degrade beamforming performance, antenna gain, pointing accuracy, and sidelobe levels. Effective calibration enables these imperfections to be identified and compensated, ensuring that the array achieves its expected performance throughout its operational lifetime.

The goal of this internship is to investigate the calibration of active phased array antennas, assess the impact of hardware imperfections on beamforming performance, and evaluate modern calibration techniques applicable to large-scale and next-generation antenna system.

Activities for this internship include: - conduct a comprehensive literature review of modern calibration techniques for active phased arrays, including conducted, radiative, adaptive and automated calibration approaches; - identify the main error sources and performance drivers affecting active phased arrays, including manufacturing tolerances, gain and phase variations, thermal drifts, mutual coupling and frequency-dependent effects; - gather and analyse performance and stability data of key array components to quantify their contribution to overall array performance degradation; - develop a representative numerical model of an active phased array using MATLAB and, where appropriate, HFSS, CST, TICRA or ADS, including realistic hardware impairments and environmental effects; - implement and evaluate one or more selected calibration techniques and assess their effectiveness, robustness and scalability in mitigating identified error sources; - summarise the findings in a detailed technical report, including recommendations, identified technology gaps and potential future developments in active phased-array calibration. ## What you will learn The intern will develop knowledge of active phased-array antennas, modern calibration techniques, RF system modelling and performance analysis, while gaining practical experience in assessing the impact of hardware imperfections and evaluating calibration approaches through numerical simulations. ## Context & Problem To monitor and track the growing number of Low Earth Orbit (LEO) satellites, next-generation ground stations require advanced active antenna systems.

Currently, market solutions are virtually non-existent or come at prohibitive costs (>€10M per system) due to the strict demands of multi-beam operation, True Time Delay (TTD) performance, and wide fields of view (FoV). Existing commercial alternatives offer limited bandwidth and a restricted number of concurrent beams.

Meanwhile, conformal solutions - like the truncated pyramid architecture using 5–6 inclined panels - add significant mechanical and structural complexity. ## Proposed Solution & Key Technical Novelties Building upon a recent ESA patent [RD1] filed in June 2026, this project focuses on optimising a completely flat active phased array capable of dynamically generating 10–12 real-time reconfigurable beams over a wide scanning range (up to 70° from boresight across all azimuthal planes). ## Key technical features and advantages include - Flat Architecture: Completely replaces complex conformal/pyramidal structures, drastically simplifying fabrication and maintenance. - Dynamic Sub-Arraying: The number and spatial layout of active radiating elements adjust dynamically per beam.

Beams pointing toward the horizon automatically allocate more elements to compensate for scan loss compared to zenith-pointing beams. - Seamless Hand-Over: Solves panel-to-panel hand-over issues inherent in multi-panel conformal systems by synthesizing all beams across a single aperture. - Maximised DC-to-RF Efficiency: Employs equi-power (uniform) amplitude excitation across active elements to optimise amplifier efficiency, using element positioning, phase tapering, and selective element activation as the primary degrees of freedom. - Interference Mitigation (Nulling): Integrates adaptive pattern nulling to enhance system resilience and support dual-use communications in contested or high-interference environments. ## Design Trade-offs & Market Impact While the flat footprint is physically larger than a truncated pyramid structure, it significantly reduces mechanical complexity.

For professional ground station applications, operational constraints on size, weight, and power (SWaP) can be relaxed in favour of maximizing RF performance - specifically EIRP, operational bandwidth, and angular coverage.

Once realised, this array architecture will offer high-value commercial opportunities across Satellite Telecommunications, Earth Observation (EO), and Global Navigation Satellite Systems (GNSS). [RD 1] P. Angeletti, M. Pellet, G.

Toso, “Method for Antenna Array Synthesis and Dynamic Operation with Steerable Main Beam and Targeted Nulls”, filed June 1st 2026, patent application PCT/FR2026/010143 ## Behavioural competencies Result Orientation Operational Efficiency Fostering Cooperation Relationship Management Continuous Improvement Forward Thinking For more information, please refer to ESA Core Behavioural Competencies guidebook ## Education You must be a university student, preferably in your final or second-to-last year of university course at Master's level.

In addition, you must be able to prove that you will be enrolled at your university for the entire duration of the internship. ## Additional requirements The working languages of the Agency are English and French. A good knowledge of one of these is required. Knowledge of another ESA Member State language is an asset.

During the interview, your motivation for applying to this role will be explored. ## Diversity, Equity and Inclusiveness ESA is an equal opportunity employer, committed to achieving diversity within the workforce and creating an inclusive working environment.

We therefore welcome applications from all qualified candidates irrespective of gender, sexual orientation, ethnicity, religious beliefs, age, disability or other characteristics. At the Agency we value diversity, and we welcome people with disabilities. Whenever possible, we seek to accommodate individuals with disabilities by providing the necessary support at the workplace.

The Human Resources Department can also provide assistance during the recruitment process. If you would like to discuss this further, please contact us via email at ESA.Student.Internships@esa.int . ## Important Information and Disclaimer During the recruitment process, the Agency may request applicants to und