RF Cable Assemblies for Ultra-Demanding Space Applications

The purpose of an RF interconnect in space is to transport a signal from one physical location to another. RF cable assemblies can make the difference between mission success and failure, as the RF interconnect is the bridge to many supporting systems, including communications, payload, signal transport and processing, and more.

Optimized RF cable assembly design is critical in space applications. The systems are mechanically and electrically exposed, and the space environment poses unique challenges. Designing a crucial interconnect system that will perform reliably and consistently over long periods of time and withstand the extraordinary environmental and technical conditions of space is nothing like designing just any RF interconnect.

Equipment used to power space technology must also be lightweight, small, reliable, and resistant to high-shock and vibration, radiation, and harsh/extreme temperatures. RF coaxial cable assemblies must be designed to perform reliably in the smallest possible footprint. The equipment must also function continuously without hands-on maintenance.

         Pre-Launch                          Launch                         Space Flight                      In Space                   Communication

Pre-Launch

Improvements and new technologies have introduced more challenges for the unique coaxial cable and connector solutions used for pre-launch. The cable assemblies must be durable enough to withstand extensive handling and continuous movement from frequent connecting and disconnecting, while maintaining precise repeatability of measurement and reliable electrical performance. It is critical that the cable, cable assembly, and connector do not introduce any problems.

Ground Testing 

• TVAC and High Power 
• Laboratory 

Launch

The backbone of any space program is the launch vehicle. Cables used for space launches need to withstand severe conditions at the lightest possible weight.

Typical challenges in determining the optimal coaxial cables and connectors for extreme conditions like space launches include evaluating factors such as signal-to-noise ratio, low loss, shielding, reliability, flexibility, superior amplitude stability, high density, low smoke, or non-outgassing materials, and more.

For cables and connectors used in space launches, extreme heat is also a crucial concern. Cables must be able to withstand extreme temperatures.

Launchers 

• Attitude Correction Module 
• Central Units / Communication 
• Command Memory Boxes 
• Control Boxes 
• Sensors 

Space Flight

In Space

Vacuum and radiation are two primary elements that pose specific risks to RF cable performance in spaceflight applications. Therefore, it is critical to specify cables that will not outgas, resist multipaction as appropriate, withstand the radiation environment, and use materials that are not susceptible to whiskering.  

There are three main types of orbit in space: Low Earth Orbit (LEO), Medium Earth Orbit (MEO), and Geosynchronous Orbit (GEO). LEO is orbit with an altitude at or below 2,000km; MEO is also known as Intermediate Circular Orbit (ICO) and is located above 2,000km but below 35,786km; GEO is located at 35,786km.

Satellites GEO/ MEO

• Navigation & Communication  
• Gamma Ray Detection  
• Weather Monitoring  
• Radio/TV Networks 
• Broadband  
• Space Environmental Sciences 

Satellites LEO

• Earth Observation  
• Surveillance  
• Telecom  
• Space Telescopes  
• Earth Sensing 
• Space Cubes 

Communication

There is a need for more data transmission volume and the ability to handle the next generation of launch vehicles. Phase is a crucial parameter for these systems relying on continuous transmission and reception of RF signals with high accuracy and consistent speeds.

Two primary elements can affect a coaxial cable assembly’s phase tracking characteristic: electrical length and temperature. Phased array radars are multi-elements and rely on coaxial cables with the same electrical lengths between the transmitter-receiver and antenna, which poses challenges when matching the cables.

Many different requirements may apply in terms of RF and microwave interconnects used with ground-based satellite dishes, such as high-frequency performance, low-attenuation needs, phase stability, and low-PIM performance. 

Ground Systems 

• Docking Systems 
• Ground Stations 
• Communications 
• Mars Rovers 
• Mobility 
• Navigation Systems