Feed System Enabling Single Reflector Beam Hopping Antenna for High Throughput Satellites

Space Segment - Payload

Status

Ongoing
Status date

2024-11-11
Activity Code

5B.168

Objectives

Broadband antennas generating multiple beams within frequency/polarisation reuse schemes fall into two categories: single feed per beam (SFPB) requiring at least three antenna apertures, and multiple feed per beam (MFPB) needing only two apertures but with greater feed system complexity. In beam hopping or switching applications, the challenges of beam generation are eased as fewer beams are active simultaneously, enabling simpler, high-performance antenna designs potentially using just one aperture. Beam hopping with dedicated pencil beams in high-traffic areas is commercially valuable, offering flexible, cost-effective traffic management.

The goal was to design an antenna system capable of generating multiple hopped or switched beams from combined or separate transmit/receive apertures, reducing the number of apertures and costs by at least half compared to current solutions. Innovative multibeam antenna solutions have been investigated for both return and forward links.

Challenges

The "Feed Systems enabling Single Reflector Beam Hopping Antenna For High Throughput Satellite” study introduces a Multi-Beam Antenna (MBA) solution designed for flexibility and high-efficiency RF performance across extensive coverage areas.

The first major challenge concern the system architectures choices. It outlines assumptions, constraints, and requirements for versatile V-HTS missions, considering frequency plans, coverage, and bandwidth flexibility. Features of TAS Spacebus-Neo and TAS Space Inspire platforms are discussed, driving the need for a new V-HTS architecture utilizing a TAS DTP6G based solution.

Benefits

Analysis activities have been carried out, highlighting the design drivers of new generation V-HTS architecture based on a TAS DTP6G solution, with the input Butler matrix of an MPA structure implemented in a digital way, as a simple application of the DBFN functionality offered by the DTP, combined use of HPA matrix and Multi-beam antennas in Mono-R configuration and its ability to densify coverage.

Separating transmission and reception antenna functions yields significant gains in Tx gain and capacity, with reduced mass and output losses, the amplifiers being as close as possible to the antennas, while greatly reducing the mass of the antenna modules.
The benefits are considerable :

Major improvement of the Tx gain (+1dB) relative to the conventional 3 Tx/Rx SFPB antennas configuration,
Huge improvement of the capacity, especially at iso-power consumed.

Features

2 products were considered :

One on SB-Neo s/c with diplexer 1x2 and 2x2 MPAs connected to 2 output ports of the DTP6G, a diplexing stage was introduced prior to the amplification, resulting in the specialization of the HPAs on a half-band, dedicated to a specific Mono-R antenna, providing 332 beams of 0.3°. In addition, the HPAs are paired into 2x2 MPA structures, allowing the dynamic sharing of the MPA power resources among 2 beams served by the same antenna.

In a flexible beam hopping system scenario, DTP ports are used at 50% with 725 MHz per user beam, the FWD throughput is estimated to around 530 Gbs. In this scenario, flexibility lies at MPA level, with 1.45 GHz to be shared within any beam pair.
- Benefit of 50% considering the K-VHTS reference scenario. ∙ In a channelized system scenario, the DTP ports are used at 100% with 1.45 MHz per user beam, the FWD throughput is estimated to around 790 Gbs with consumer terminals, with no allocation flexibility.
- Benefit of 125 % considering the K-VHTS reference scenario. One on the Space Inpire s/c with 2x2 MPAs connected to 2 DTP outputs ports; includes a single passive Tx Mono-R antenna, with a square beam layout, defined at CDR for 100 beams of 0.56°, covering the same full mission area.
In a flexible beam-hopping system scenario; a 237 Gbps FWD throughput is achievable with consumer terminals and a flexible beam hopping system. A limited number of gateways (x13) is however required in an RF feeder based solution.

System Architecture

The system comparison was focused on the following parameters :

System increasing the number of beams in the coverage,
System increasing the frequency band capacity at iso-power consumed (lower PIRE density),
Amplification technology (mass, consumption, dissipation, redundancy management) with Mini-TWT vs SSPA Ka band,
Performances looking at 2 colors FFR (Fractional Frequency Reuse) versus conventional 4 colors schemes,
Definition, analyses and interest of MPA 2x2 solutions.

The separation of the transmission and reception antennas functions in independent sub-arrays, is naturally conceived on the SPI platform for which the repeater is specialized with on the one hand a HPA matrix on the East face and on the other hand, the receive RF chains on the other satellite side/face.

Plan

This study was divided in five phases:

Beam Hopping antenna Technical Requirements, This phase is devoted to recall the possible architecture of beam hopping based solutions, to identify the motivations for considering beam hopping system and finally, to consolidate antenna technical requirements.
Antenna Concept Baseline for Feed System Development, This phase is devoted to identify the preferred beam hopping system and propose antenna concept and associated technologies.
Feed System Detailed design & Analysis & EM definition, This phase is devoted to the antenna feed system architecture trade-off, focused on solutions based on the combined use of HPA matrix and Multi beam antennas in single multibeam antenna (Mono-R) configuration.
Manufacturing and assembly of the EM feed system, This phase was devoted to the manufacturing of the Engineering Model,
RF Test results of the EM feed system This phase was devoted to the tests of the Engineering Model.

Current status

The activities performed on Feed Systems enabling Single Reflector Beam Hopping Antenna For High Throughput relative to ARTES AT 5B.168 - contract 4000129443 brings a major step for future Ka flexible Ka V-HTS system.

A development plan to make the selected antenna/feed system commercially available has been produced, fixing the TRL at the 7th level, compatible with a medium/long-term (2025 timescale) for its achievement. An antenna demonstrator showed the high degree of maturity of the solution.