Flexible Alternatives to Semi-Rigid Cable Assemblies

By Joana Rodrigues | May 13, 2025

As system complexity increases and space constraints tighten, a more adaptable solution has become necessary — without compromising the critical electrical performance requirements that make semi-rigid cables the current standard.

In the demanding environments of aerospace, defense, and telecommunications systems, reliability is not just desirable, it’s essential. For decades, semi-rigid coaxial cable assemblies have been the industry standard, valued for their excellent electrical performance, phase stability, and shielding effectiveness. These traditional assemblies excel in harsh operating conditions but bring significant design and installation challenges due to their inherently rigid construction. As system complexity increases and space constraints tighten, a more adaptable solution has become necessary — without compromising the critical electrical performance requirements that make semi-rigid cables the current standard.

The semi-rigid challenge

Semi-rigid coaxial cable assemblies have long been favored for their superior electrical performance characteristics. Their solid copper outer conductor provides excellent shielding from electromagnetic interference (EMI) and maintains stable phase performance across environmental variations — crucial factors in radar systems, communications equipment, and other high-frequency applications where signal integrity is paramount.

However, these performance benefits come with considerable drawbacks:

Installation complexity requiring precise 3D bend configurations
Limited ability to make field modifications
Higher installation costs due to hand forming or specialized bending equipment
Increased risk of damage during installation
Difficulty accommodating design changes or system modifications

For engineers and system integrators, these challenges translate into longer development cycles, increased installation costs, and reduced design flexibility. As systems become more complex and space-constrained, these limitations have intensified the need for alternatives that can provide comparable electrical performance with improved mechanical properties.

The flexible alternative: A new paradigm

Flexible alternatives to semi-rigid cables represent a significant advancement in RF transmission technology. These solutions deliver the electrical performance of semi-rigid assemblies while offering the installation benefits of flexible cables. Among the leading options in this category is TFlex, a high-performance microwave cable designed specifically as a drop-in replacement for semi-rigid coaxial assemblies.

Unlike traditional flexible cables that sacrifice electrical performance for mechanical flexibility, this advanced alternative maintains critical parameters such as low insertion loss, excellent shielding effectiveness, and phase stability even when subjected to bending and flexing.

TFlex meets all MIL-DTL-17 requirements while offering installation simplicity previously unavailable with semi-rigid options. The innovative construction combines multiple performance-enhancing elements:

A silver-plated copper center conductor maximizes signal transmission efficiency
Solid PTFE dielectric material provides excellent electrical properties and temperature stability
A double-layer shield design incorporating helical wrap of silver-plated copper tape and an overall braid delivers superior EMI protection
A durable FEP outer jacket offers environmental protection in corrosive environments

This construction achieves a critical balance between flexibility and performance. The helical wrap and braided shield configuration allow the cable to be bent without specialized equipment while maintaining comparable electrical characteristics to semi-rigid assemblies.

Performance characteristics: Meeting critical requirements

In aerospace and defense applications, performance stability across environmental extremes is non-negotiable. TFlex maintains stable loss, phase, and VSWR (Voltage Standing Wave Ratio) characteristics even with flexing, a critical requirement for systems where signal integrity directly impacts operational effectiveness.

Key performance advantages include:

Excellent shielding effectiveness protecting sensitive components from external interference
Low passive intermodulation (PIM), ensuring signal clarity in multi-channel systems
Compatibility with standard solder-on semi-rigid connectors, simplifying integration with existing systems
UV-resistant, flame-retardant outer jacket suitable for diverse installation environments

The ability to maintain these performance characteristics while offering improved installation flexibility represents a significant advancement for system designers.

Application benefits in critical sectors

Aerospace

In aircraft and satellite systems, weight reduction and simplified installation are paramount concerns. Flexible alternatives like TFlex eliminate the need for precise pre-forming while reducing installation time and the risk of damage during assembly. The stable phase performance critical to radar and communication systems is maintained despite the more flexible construction.

Defense

Military applications require solutions that can withstand extreme conditions while delivering consistent performance. The durable construction of TFlex provides excellent protection in corrosive environments while its stable electrical characteristics ensure reliable operation of sensitive equipment. The ability to make field modifications—difficult or impossible with traditional semi-rigid assemblies—enhances serviceability in deployed systems.

Telecommunications

As telecommunications infrastructure becomes more densely packed, the ability to route cables in tight spaces without sacrificing performance becomes increasingly valuable. Flexible alternatives simplify installation in crowded equipment racks and enclosures, reducing assembly time while maintaining the signal integrity critical to high-bandwidth applications.

Integration and implementation

One of the most significant advantages of advanced flexible alternatives is their compatibility with existing systems. TFlex uses standard solder-on connectors, allowing for seamless integration with established designs. This compatibility extends the benefits of flexible construction to legacy systems without requiring wholesale redesigns.

For new designs, these flexible alternatives open new possibilities for compact, efficient layouts that would be impractical with semi-rigid assemblies. Engineers can now route cables through complex paths without the precise bend planning required by semi-rigid options.

The path forward

By combining the electrical performance of semi-rigid cables with the installation benefits of flexible options, TFlex expands design possibilities while reducing complexity and costs. A significant advantage over traditional semi-rigid solutions is TFlex’s immediate accessibility through distribution as raw cables, connectors, and complete assemblies. This eliminates the extensive design hours and specialized forming equipment typically required for semi-rigid implementations.

As aerospace, defense, and telecommunications systems advance, the demand for components delivering both performance and practicality continues to grow. Flexible alternatives like TFlex meet this demand by maintaining critical performance characteristics while offering a comprehensive ecosystem of compatible products through standard distribution channels.

Learn more at Times Microwave Systems.