Cable Assemblies and the Electronic Warfare Program
By Stephen Sacco and Jihan Mohammed, Rosenberger of North America

The U.S. Navy is the coordinating service branch charged with developing the nation’s Electronic Warfare (EW) program. It has initiated a program to develop the next generation of the Joint Counter Radio-Controlled Improvised Explosive Device (RCIED) Electronic Warfare (JCREW) 3.3 System to detect and jam Improvised Explosive Devices (IEDs). Additionally, the Office of Naval Research (ONR) has announced its intention to direct improvements of existing JCREW system hardware, software, techniques, and technologies. The system is intended to provide protection to foot soldiers, vehicles, and permanent structures.

The new designs require transceiver components to support more than 100MHz per channel instantaneous bandwidth, with efficiencies of more than 40 percent. Signal generation must be multiple, simultaneous, and low-noise waveform capable. Jamming responses necessitate high-speed activation to GHz bandwidths, and waveform generation must be switchable at nanosecond speeds.

Antennas, which are available for mounted and dismounted applications and have very broad bandwidth to reduce the number of antennas necessary to cover mid-LF (Low Frequency) to mid-EHF (Extremely High Frequency) applications, are also necessary. Mounted applications are typically used in combat and communication vehicles, such as the Humvee. Dismounted applications include portable communication and detection systems, as well as the Land Warrior (man-portable) systems.

Each application requires interconnect solutions that accommodate the unique electrical and physical operational environments. For example, the vehicle mounted systems must be rugged and capable of withstanding direct environmental exposure and the rigors of the battlefield. These systems are typically higher power and have more massive components.

The smaller, lighter Land Warrior systems require smaller, lighter weight interconnections, but ease of use, performance, and durability must be maintained. These fielded systems are many times more numerous than vehicular systems, so the supplier must have considerable resource capability in design, manufacturing, and testing. The availability of a reliable and proven source of RF cable assemblies and interconnection solutions is critical to achieving the government’s—and therefore the EW system designer’s—critical objectives.

The controlled impedance interconnect industry has supplied several hundred thousand preformed semi-rigid (hard line) cable assemblies, and an equivalent number of flexible/hand-formable assemblies and antenna cables directly to the JCREW, CVRJ (CREW Vehicle Receiver/Jammer), and similar programs. These assemblies have been in the field since 2006. The supplier must be committed to providing reliable coaxial interconnect solutions in support of these new—and future—requirements.

Successful suppliers will have proven experience in applicable leading-edge RF design and manufacturing technology. Internal quality systems and programs must be capable of electrical and mechanical metrology and in-process controls to assure the exacting military requirements are met.

The broad range of interconnection products in the EW marketplace means that suppliers must be fully integrated and possess a trained, flexible workforce. Suppliers must have the capacity to quickly produce unique tooling as part of the integration. A core competence in RF design and manufacturing technology is essential. The ability to quickly progress from application engineering through design engineering and into manufacturing engineering cannot be overstated. Design for manufacturing is a critical capability.

For example, the introduction of corrugated antenna cable into the EW battlefield environment quickly and directly addressed the EW designer’s demands for lightweight, flexible, ruggedized, weather-proof assemblies. These cables, typically terminated with Type N, TNC, or 7-16 connectors, have decades of field-proven durability and electrical performance in the demanding cellular infrastructure marketplace.

Prior to use in military field applications, Type N connectors, for example, had specified criteria only for axial and torsion forces with respect to cable interconnection. In one case, it was learned that a third criteria, a perpendicular force moment some distance away from the cable interconnect point, needed to be specified. This resulted in a significantly improved and stronger connector for the application. Because the connector manufacturer and cable assembly manufacturer were part of the same company, the change was implemented and in the field within a matter of weeks. 

In the case of soldering technology, the global tendency toward RoHS compliant (lead-free) solders, contrasting with the fact that the military does not allow lead-free solders to be used, means that the supplier must have segregated manufacturing cells. The European Union Directive, which specifies RoHS compliance, does not allow lead-free and leaded soldering cells to be integrated. Similarly, military soldering cells may not contain lead-free solders. The manufacturer must have two distinct material control systems. 

Semi-rigid (hard line) pre-formed cables offer solid, durable, repeatable designs with predictable performance. A complete line of standard connector designs with weights and costs comparable to flexible cable makes these cables an excellent choice for system designers. These battle-proven and easily replaceable (for damage or upgrade) assemblies have become the standard for EW circuit designers in sea, land, and air environments.

Semi-rigid (hard line) cables represent the most stable, predictable cable designs in both electrical and mechanical performance. These cables are pre-formed to unique shapes that fit precisely into the designated circuit segment. Additionally, the electrical performance of each cable is measured after the shape has been formed. As the cable shape does not change, the performance remains constant, unlike flexible or hand-formable cables, which are tested in the straight condition, and then mechanically routed and formed by the circuit builder. The fact that semi-rigid cable has a solid (tubular) outer conductor means that RF leakage from the cable is essentially eliminated. This is a critical feature in highly populated and/or proximity sensitive designs.

Today’s modern CAD design and CNC bending equipment has significantly reduced the premium cost formerly associated with semi-rigid cables vs. their flexible counterparts. A CNC bender forming hard line assemblies is pictured above, right.

Hand-formable/flexible cable assemblies complete the interconnect design choices for EW systems. These insulated or un-insulated options have found broad acceptance in applications, from commercial to military. For example RTK-028 Triple-Shielded 0.087-inch (diameter) ultra-flexible cable was recently introduced to the military and EW market. This cable has been praised by instrument designers and manufacturers for its superior RF shielding and flexibility. Precision length-management protocols make the range of cables phase-matchable and stable to values approaching semi-rigid. A broad range of connectors is also available to the designer.

Supporting the military, and more specifically the EW programs, requires significant commitment and resources. The increasing demands on electrical, mechanical, and environmental performance, in addition to compressed product development cycle times, are challenging under normal circumstances, but more critical when we have troops in harm’s way.

For more information, contact Rosenberger NA at info@rosenbergerna.com.

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Stephen Sacco, PhD., ScD., has been director of operations for Rosenberger of North America LLC since 2002. He has more than 30 years of RF technology and manufacturing experience. Sacco has directed research projects and authored numerous papers and articles dealing with material properties at high frequencies, including solder and solder-ability, RoHS compliance, hermetic RF feed-through, and PTFE dielectric properties.

Jihan Mohammed, MSME, BSME, has been the director of engineering at Rosenberger of North America LLC since 1999. Prior to joining Rosenberger, Mohammed held engineering and engineering management positions at ITT Sealectro, Specialty Connector, and Amp/Tyco.