SIST EN 4604-004:2009

Overview

SIST EN 4604-004:2009 is a European aerospace standard that specifies the essential characteristics and performance requirements for microcoaxial cables, type WS, designed for signal transmission in aircraft electrical systems. These high-immunity cables are engineered to operate reliably in harsh aerospace environments with temperature ranges from -55 °C up to 200 °C. Rated at 50 Ohms impedance and supporting high-frequency signals up to 3 GHz, this standard ensures cables meet stringent electrical and mechanical qualities required for radio communications and other high-frequency aerospace applications.

Developed under the authority of the Aerospace and Defence Industries Association of Europe (ASD-STAN) and ratified by CEN, the standard guides manufacturers, designers, and quality assurance professionals in aerospace infrastructure, emphasizing durability, safety, and performance compliance.

Key Topics

• Material and Construction
  EN 4604-004 defines precise materials for cable components:

  • Silver-plated multi-strand copper conductor (1 µm plating) meeting ASTM B 298-99
  • Fluorocarbon dielectric
  • High permeability tape screen
  • Silver-plated copper braid shield
  • Amber polyimide tape jacket

• Electrical Specifications

  • Characteristic impedance: 50 ± 5 Ω
  • Capacitance: 95 ± 10 pF/m
  • Transfer impedance: Maximum 45 mΩ/m up to 100 MHz
  • Attenuation and power ratings optimized for frequencies up to 3 GHz (e.g., attenuation 26 dB/100 m at 50 MHz)
  • Operating voltage: 1.3 kV RMS
  • Velocity of propagation: 0.69 c nominal

• Mechanical and Environmental Characteristics

  • Operating temperature range: -55 °C to 200 °C
  • Minimum bend radius: 15 mm (static), 28 mm (dynamic)
  • Cable outer diameter approximately 2.5 mm
  • Mass: approximately 20 g/m

• Testing and Quality Assurance
  The standard mandates rigorous testing protocols in line with EN 3475-100, covering:

  • Visual inspection, dimensional checks, and mass verification
  • Electrical tests including insulation resistance, voltage proof, and characteristic impedance
  • Mechanical endurance tests such as bending, abrasion resistance, and flexure endurance
  • Environmental resistance tests including rapid temperature changes, thermal stability, and fluid resistance
  • Smoke density and toxicity assessments for safety compliance

• Marking and Packaging

  • Identification marking in black as per EN 4604-002
  • Delivered typically on drums with lengths around 200 meters, minimum 50 meters per piece
  • Packaging aligned with EN 4604-001 standards

Applications

EN 4604-004 microcoaxial cables are specially intended for use in aerospace electrical systems requiring reliable, high-frequency signal transmission under extreme temperature and mechanical stress conditions. Key application areas include:

• Aircraft Radio Communication Systems
  Providing stable and high-immunity signal paths for avionics and radio frequency transmissions up to 3 GHz frequencies.

• Avionics and Onboard Electronics
  Ensuring electrical integrity and shielding against electromagnetic interference within flight control systems, navigation units, and monitoring instruments.

• Military and Defense Aerospace Platforms
  Supporting robust communication and data transmission infrastructure meeting stringent aerospace operational demands.

• High-Performance Aerospace Wiring Harnesses
  Integrated into complex cabling assemblies requiring lightweight, flexible, and durable cables with stable electrical properties.

Related Standards

• EN 3475-100 - Aerospace cables testing methodologies, general requirements for validation of electrical and mechanical properties.

• EN 4604-001 - Technical specifications for aerospace electrical cables, including detailed design and performance requirements.

• EN 4604-002 - General standards for marking and identification of aerospace electrical cables.

• TR 6058 - Aerospace cable code identification list facilitating uniform part identification and traceability.

• ASTM B 298-99 - Specification for silver-coated copper wire-material foundation for cable conductors and shields.

Understanding SIST EN 4604-004:2009 is essential for aerospace manufacturers, engineers, and quality assurance teams engaged in developing or specifying high-performance microcoaxial cables optimized for demanding aerospace environments. Compliance with this standard guarantees cables that combine thermal endurance, electrical performance, and mechanical resilience critical for modern aerospace signal transmission systems.