PAGE CONTENTS
Objectives
Recently, there is an increasing incidence of unauthorized ground transmitters targeting civil communications satellite transponders with the intent to take advantage of fraudulent access or interfere with the wanted signals causing a consequent reduction of the transponder capacity, typically known as Denial-of-Service (DOS). Consequently, there is an increasing interest of satellite operators in feasible solutions to mitigate interfering source. The ESA study “Adaptive Antenna for Telecommunication Links” addresses the request to investigate antenna architectures able to shield a single selectable transponder channel of 36 MHz by the modification of an existing payload for broadcasting coverage application.
The objectives of the ESA activity is to investigate the baseline adaptive architectures applicable to existing satellite antenna systems with Focal Array Fed Reflector Antenna or Shaped Reflector Antenna designs. The adaptive antenna exhibits the capability to adapt the broadcasting radiation pattern to provide a null along the interferer direction, in a particular frequency channel, and minimize the DOS coverage area.
The strategy proposed in the study is able to provide this feature and it foresees to combine two radiation patterns of the same antenna where the first one is the main pattern, corresponding to the nominal shaped coverage and the second is the auxiliary pattern that realizes a pencil beam pointed towards the interferer and correctly weighted to create a null.
Challenges
The main challenges tackled in this activity are the following:
- Design of the adaptive antenna system to be integrated in the FAFR and Shaped Reflector configurations.
- Trade-off and identification of the most efficient Nulling Algorithms for this application.
- Design of the RF chains to be integrated in the existing antenna system for down and up conversion of the selected 36 MHz channel signals useful in the digital processing.
- Design of the digital system.
- Manufacturing of the adaptive demonstrator antenna that is representative of the FAFR antenna configuration able to implement the feature of the designed architecture.
- Test of the Adaptive Algorithm performance using the Demonstrator antenna and evaluation of pros and cons among the different Nulling Techniques.
Plan
The overall activities of this project have been split into two phases (Phase 1 and Phase 2). Phase 1 and the Phase 2 of the project have been carried out with the following milestones, with the related major achievements:
Phase1:
- KO (Kick-Off),
- BDR (Mission and Antenna Baseline Designs, Threat Scenarios, Vulnerabilities Identification and Mitigation),
- PDR (Adaptive Antenna System Preliminary Design and Analysis).
Phase 2:
- FR (Adaptive Antenna System Detailed Design, Demonstrator Manufacturing and Tests, Analysis and Cost Effectiveness Evaluation),
- FP (Final Review and Final Presentation).
Current Status
All the activities foreseen for Phase 1 and Phase 2 of the contract have been carried out.