Key Considerations for Coaxial Cables in Space

Phase Stability

For phase-sensitive systems, compensating for the knee multiple times per orbit as the spacecraft moves through its operating temperature range is challenging and limits overall system performance. Other dielectrics such as Times Microwave’s TF4^® dielectric and Sio2™ silicon dioxide materials do not produce a similar non-linear change. In addition to controlling overall phase change vs. temperature, designers may need to characterize the hysteresis of the phase change across the operating temperature range. The silicon dioxide dielectric provides linear phase change with exceptional repeatability for applications requiring low hysteresis.

Return Loss

The second major environmental consideration for spaceflight applications is electrical performance over radiation exposure. Plastics such as PTFE and TF4 will degrade over time, increasing loss. For short-duration or risk-permissive missions, these long-term concerns may not be compelling. For long-duration, high-exposure, or high-reliability missions, using radiation-tolerant coaxial solutions such as the SiO2 line is better than shielding a plastic.

High Density

The high-frequency cables required for spaceflight applications have a shorter range, requiring a dense network of antennas.

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. Our TCOM^®, MaxGain^®, and LMR^® products are designed to address these needs.

At the same time, technology providers are working on advanced designs that accommodate extremely restricted space constraints and producing spaceflight connectors that successfully operate up to 70 GHz. Our new InstaBend high-performance microwave assemblies provide a flexible preassembled design for interconnects between RF circuit cards, modules, and enclosure panels, enabling space-efficient implementation for higher frequencies.

The high-performance microwave assemblies are ideal for in-the-box applications because the cable can be bent very closely behind the connector. This minimizes footprint, saves room, and simplifies cable routing, eliminating the need to protect the back of the connector.

Materials

In addition to the issues of smaller cables tightly packed and connected, space applications require materials and constructions that withstand radiation, sandblast storms, extreme temperatures, and pressure variations. The latest materials technology and manufacturing processes are needed.

In the past, semi-rigid cables have been the standard cabling solution in space applications because their solid copper outer conductor protects the dielectric material inside. Today, special semi-rigid cable solutions based on silicon dioxide dielectrics are available. For example, our SiO2 cable assemblies are highly temperature and radiation resistant.

Some antennas fold into the satellite when not in use and unfold upon arrival at the satellite’s destination. There, the antennas will point to other satellites, get a position, and lock mechanically. Flexible cables are needed to work around the elbow that enables the antenna to fold and unfold.

Connectors

New styles of connector interfaces such as Times Microwave’s TLMP address the electrical and mechanical weaknesses of traditional high-frequency SMP/SMPM interfaces for high-vibration spaceflight applications. They visually indicate full engagement by exposing a green ring on the connector body when successfully mated.

Once routed correctly, it is also critical to ensure that the cable is appropriately mated to ensure effective RF performance. For threaded connectors, RF assembly suppliers should be able to provide recommended connector torque values. Designers should also consider multiport connectors that will mate multiple contacts simultaneously, reducing the opportunities for error.

Times Microwave Systems^®: The Ideal RF Interconnect Partner for Demanding Space Applications

Qualifications and Heritage

Our team has deep experience in space and other mission-critical industries such as military and defense.

Breadth of Products

Components deployed in space must meet many technical standards. There is, however, no standard for how to apply these materials to construct a consistently reliable RF solution. That is where our expertise and access to a full range of product options are needed.  You can select the suitable material and choose from multiple cable constructions, various connector designs, and assembly techniques, all from the same supplier.

Dedicated Technical Experts

The complexity of space applications requires an effective partner who will work collaboratively to extend your design team. We help our partners understand the electrical and mechanical trade-offs particular to their unique space applications. Our technical team asks the right questions and listens to understand your unique needs, always considering innovative solutions.