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Last Update: 03 Nov 2010
Payload equipment

Electromagnetic Satellite Analysis Tool


 

Objectives

The Electromagnetic Satellite Analysis Tool (ESAT) project aimed to create a software tool to analyze the radiated susceptibility of the payload to the electromagnetic field in the Communication Module. Leakages from RF units and electromagnetic fields generated by external antennas, which penetrate inside the Communication module through apertures in the satellite structure, are considered.

The tool integrates into a unique modelling environment (named Antenna Design Framework- ElectroMagnetic Satellite) two numerical solvers based on the Oversized Cavity Theory and on the Synthetic Function Expansion method.

The dynamic between the input and output chains of a telecommunication payload repeater can be as high as 120dB, which requires the need of adequate analyses and engineering solutions to ensure electromagnetic compatibility.

This project has been focused on the development and validation of modelling methods to evaluate the electromagnetic environment inside the Communication Module (CM), taking into account the leakages of the high power RF units inside the CM and the stray fields generated by the payload antennae that penetrate inside the Module through the apertures in the satellite body.

The developed modelling codes have been integrated into a new release of the CAE framework ADF-EMS (Antenna Design Framework – ElectroMagnetic Satellite), thus providing the Users with controlled GUI based, industrial-like working procedures.

In the latest phase of the project, the tools have been validated against measurements performed on a mock-up and finally applied to a realistic case study.

Features

The project has been finalized by developing working procedures and CAE tools for industrial oriented Users, implementing the above mentioned numerical models and also other existing companion or parallel procedures.

The CAE tool, ADF-EMS (Antenna Design Framework – ElectroMagnetic Satellite) has been selected as the SW platform to be upgraded with new capabilities.

One of the problems related to the utilization of the OCT in the frame of real operating scenarios, is its complexity in terms of the number of data (cavities, panels, apertures) and the topological relation between them. This difficulty has been overcome by designing a driven GUI that allows:

  • An easy and intuitive definition of each input data;
  • A high level system view, to synthetically identify all the components involved and their relations (i.e. cavity interconnections, which emitters in which cavities, etcetera).

In particular, a hierarchical modelling approach was adopted:

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and it was “naturally” represented through a tree structure into the main GUI of the OCT model, where each node represents an object and the tree level, its hierarchy.

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A satellite is, therefore, modelled as a set of interconnected cavities made by conductive or absorbing panels. A set of apertures can be opened on the panels thus connecting the spacecraft with the external world or interconnecting two internal cavities. Each cavity can contain devices acting as transmitter and/or receivers, absorbing devices can be taken in to account too.

Project Plan

The project activities have been be carried out in 3 main phases:

PHASE 1: review of the requirements, analysis of the scenarios of interest and assessment of algorithms, methods, working procedures etc.

PHASE 2: modelling methods and tools development and validation.

PHASE 3: SW environment and working procedures development; evaluation of the environment on a representative configuration.


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Challenges

The project has a twofold objective: the development of efficient numerical methods for the evaluation of electromagnetic environment inside the Communications Module and the implementation of working procedures for their usage in a CAD framework.

The key issues faced during the activities have been:

  • The improvement of modelling methods in the “low-frequency and near resonance” regions, when the cavity dimensions are small or comparable to the wavelength.
  • The development of a numerical method suitable for the high frequency region, where the electrical dimension of the cavity is large. It should be noted that the modelling of the electromagnetic phenomena of interest can be really challenging for any “standard” simulation methods. Numerical full-wave methods such as Method of Moments, Finite Difference Time Domain and Finite Elements fail as soon as the HW resources at disposal don’t provide the needed computational power. On the contrary, the asymptotic methods usually applied for scattering evaluation, in quasi-optical region, completely fail to model the resonance effects of internal environments. In the frame of this contract, the Oversized Cavity Theory (OCT) Method has been selected.
  • The development of working procedure for the developed numerical methods and their implementation in an industrial simulation environment.

Benefits

The developed tool offers the following benefits:

  • Improvement of numerical techniques for the analysis of the problem in the low frequency region by means of the integration of Synthetic Function Expansion method into an already existing commercial code based on method of Moments,
  • Extension and improvement of the Oversized Cavity Theory Method for the analysis of the problem in the high frequency region,
  • Integration of the numerical method and working procedures in a commercial modelling environment.

The final outcome of the project is the upgrade of the framework ADF with numerical techniques suitable to analyze and verify the radiated emissions and radiated susceptibility occurring inside the Communication Module of a spacecraft.

 

The availability of the OCT method, the ease of use of the developed working procedures and its integration in a unique modelling environment represent a unique capability not available in any other commercial tool.

Current Status (dated: 28 Oct 2010)

The project has been fully completed and all the expected activities have been performed successful.

In particular following achievements have been obtained:

  1. A new technique called Synthetic Function eXpansion Method has been implemented into the IDS Method of Moment code named IDSMMMP and proved on typical RE/RS problems;
  2. A numerical code based on the Oversized Cavity Theory Method (OCT) has been created and integrated in the IDS framework, named ADF;
  3. Numerical and analytical methods for aperture modelling to be used in conjunction with OCT have been developed and integrated into ADF;
  4. A mock-up, representative of a satellite platform with a set of apertures of different shapes and dimensions on the walls has been designed and realized.
  5. Exhaustive experimental activities have been performed with the goal of validating the modelling algorithms and procedures for the evaluation of the e.m. field inside the satellite platform, due to the radiating antennas externally located or emitting units located inside (e.g. high power units).


Last Update: 03 Nov 2010
 
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