IDS Ingegneria dei Sistemi

EMI/EMC Prediction Services



IDS Prediction services for Electromagnetic Interference and Compatibility (EMI/EMC) cover installed antenna performance optimization, system level performance optimization, EMI risk assessment and control, Link budget analysis, Rotor Blade Modulation (RBM) effects evaluation, High Intensity Radiated Field (HIRF) and risk assessment of the indirect effects of lightning and its mitigation. All these activities are performed using E-MIND, our software product for the assessment and design of the electromagnetic performance of aeronautical platforms.

Installed antenna performance optimization

The proliferation of installed antennas and services causes installation problems, especially on small/medium size aircraft, helicopters and UAVs where only a limited portion of the airframe surface is usually suitable for antenna location. Consequently antenna installation has to be optimized right from the platform design phase to satisfy the specific coverage and performance requirements of all the services.

The Aeronautical Division has acquired extensive experience in performance assessment and optimization of installed antennas and systems. In particular we are able to identify the installation position which reduces the antenna pattern distortion due to interaction with the aircraft's structure and other antennas, minimizes the inter-antenna coupling and optimizes the installed system's performance (single and multi-antenna system coverage, TCAS bearing error, VOR bearing error, etc).

EMI risk assessment & reduction

Aircraft and helicopters carry an ever increasing number of radio systems: navigation aids (VOR, DME, GPS...), communications (HF and V/UHF radio services, satellite links) and radio assistance (IFF, TCAS...). This causes possible ElectroMagnetic Interference (EMI) among co-installed systems.

The Aeronautical Division is specialized in EMI risk assessment and reduction: our consultancy services are aimed at identifying possible interfering systems and suggesting EMI risk mitigation actions (e.g. antenna installation in a different location). This is a cost-effective support especially in the early design phase when different system configurations can be investigated and checked at very low cost.

Link budget analysis

The performance of communications systems and NAVAIDS in typical operational conditions (i.e. taking into account aircraft attitude) can be affected by many factors: installed antenna pattern distortion, multipath effects, propagation losses etc. For this reason the prediction of communication link quality (link budget analysis) is essential especially for those systems which may affect mission effectiveness, safety and success (e.g. control and data links for UAVs). Link budget analysis is also useful for preliminary certification purposes.

The Aeronautical Division is able to identify possible communications problems (i.e. blind angular regions), understand the reasons of such limitations and suggest cost effective solutions.

Rotor Blade Modulation evaluation

Rotating parts, such as main and secondary rotors for helicopters and propellers for aircraft, may induce parasitic amplitude and phase modulation on the signal received by on board equipment. Whenever this modulation has a frequency comparable to any of the installed systems (e.g. 30 Hz for VOR, 90 and 150 Hz for ILS), the performance degradation has to be verified and compared to the service requirements.

The Aeronautical Division is able to estimate the effect of the rotating parts on receiving antennas (e.g. gain and phase modulation) and received signals (e.g. carrier phase and frequency modulation), to produce reports allowing a clear understanding of the system performance degradation and to identify solutions aimed at satisfying service requirements.

High Intensity Radiated Field analysis HIRF

In the recent past many mechanical devices have been replaced with electronic circuits. Unfortunately electronic circuits may respond to any input which can couple to the wire bundles, integrated circuits, electrical junctions etc. Moreover, the use of composite materials is reducing the electromagnetic shielding capabilities of aircraft while the number and transmitted power of radio frequency emitters is increasing. In this scenario the identification and control of the risk of electromagnetic interference among safety critical electronic devices and the ElectroMagnetic Environment (i.e. impinging external field or on-board transmitting antennas) is a crucial issue.

The Aeronautical Division is able to provide support to aircraft design and certification according to HIRF regulations: electromagnetic environment and harness modeling, field-field and field-currents transfer functions evaluation, identification of possible solutions (harness routing optimization, aircraft structure and cable shielding capabilities improvement, grounding enhancement) to improve safety margins and reduce the testing phase (HIRF routes to compliance).

Lightning analysis

On-board electrical and electronic devices may be damaged by current and voltage levels induced at their interface by a lightning strike. For this reason a proper protection against the indirect effects of lightning has to be designed especially for safety critical systems. The lightning certification process is specified by international regulations and it is mainly based on testing activities which are expensive and time consuming. For these reasons Aeronautical industries are pushing towards the use of a numerical modeling and analysis approach to reduce design and certification times and costs.

The Aeronautical Division has been providing consultancy services to support the design and certification of aircraft against the indirect effects of lightning since 1995: e.g. A109 helicopter certification (in collaboration with Agusta) using a simulation approach (only numerical modeling and analysis) agreed with the Italian Authorities (ENAC).

Our consultancy services include: harness modeling, voltage and current transient level evaluation, identification of possible solutions (harness optimal layout, cable and aircraft structure shielding improvement, equipment interface protection enhancement, etc) to improve safety margins.

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