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July 20, 2021updated 23 Nov 2021 12:20pm

Times Microwave Systems: Designing safety into high-performance, ultra-reliable RF systems for shipboard applications

One of the most critical dangers on a ship is fire. In confined spaces, fire quickly fills an area with smoke, which can drastically impede safe evacuation.

By Kathleen Marsh

One of the most critical dangers on a ship is fire. In confined spaces, fire quickly fills an area with smoke, which can drastically impede safe evacuation. It becomes difficult for passengers to find exit signs, for example. Added dangers include toxic gases and a lack of replacement air, especially on a submarine.

If a fire occurs in this type of confined space, it is crucial that the wiring and cables on board do not give off toxic or optically dense gases. The more cabling required in a confined space, the more important it is to use low smoke/zero halogen cables for passenger safety. This is especially true in areas where large amounts of cables are installed within proximity to humans or sensitive electronic equipment, such as on submarines and naval warships.

When burned, a low-smoke cable (also known as limited-smoke cable) emits a less optically dense smoke that releases at a lower rate, which makes exiting a space easier for occupants as well as increases the safety of firefighting operations.

Halogens like chlorine, fluorine and bromine are often used as effective fire retardants in wire and cables, enabling a cable to pass an industry flame test. However, halogens give off toxic gases when burning, so zero halogen cables are another important specification for shipboard systems.

Mission-Critical Shipboard Application Examples

Radio frequency (RF) systems are used to support vital functions such as shipboard communications and electronic warfare systems. These systems must be extremely reliable and continually offer high performance – in especially demanding and variable environments – alongside all the other technologies running simultaneously on a ship. Each of these uses has a unique set of requirements, driving implementation of custom solutions that address application-specific challenges.  And while safety comes first, performance must be flawless.

Shipboard Communications Systems

Shipboard communications systems are designed to provide reliable connectivity across great distances. Powered by RF technology, shipboard communications systems include point-to-point, ship-to-ship, ship-to-shore, ground-to-air, land mobile radio, satellite communications and more. What these applications all have in common is that they need to carry a signal from point A to point B without loss or interference. Any degradation of the signal may cause critical information to be lost.  Low smoke coaxial cables are often routed throughout the ship to carry these signals.

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Typical challenges in determining the optimal coaxial cables and connectors for shipboard communications include signal-to-noise ratio, low loss, shielding so that signals from outside cannot interfere, and the need for reliability. Often, the coaxial cables used for these applications must also meet the MIL-17 standard. While this is a US standard, it is frequently used globally to ensure the cable meets the necessary requirements.

Coaxial cables need to be easily and reliably terminated in the field. Many options currently available in the market only address cable requirements, often neglecting connectors, which can cause termination failures and inconsistencies. To mitigate this issue, Times offers a complete line of MIL-DTL-17 qualified cables and connectors that can be assembled using a compact prep tool. Using this system of matching cables and connectors, installers can route the LLSB cables throughout the ship and effortlessly terminate them while meeting many requirements, including temperature ratings of -40°C to 125°C, as well as IAW MIL-PRF-39012, MIL-STD-810 and MIL-STD-202 requirements.

Times Microwave’s high-performance LLSB™ cables are flexible and can be easily routed into and through tight spaces without kinking. A very tight minimum bend radius provides superior flexibility compared to previous generation corrugated copper, or smooth wall copper hardline cables. This enables easy installation and maintenance even in very tight spaces.

These cables are fully qualified to the latest MIL-DTL-17 requirements, and maintain a full Qualified Products Listing (QPL), under the M17/220 through M17/229 slant sheets. Unlike other products available in the industry, the LLSB line is the only coaxial cable family available with a complete line of field-installable connectors with assigned DLA part numbers and prep tools designed to make cable termination easy and consistent.

This line of FITS connectors allows for easy and reliable cable termination in the field with no soldering required, saving time and cost on installation. They are designed with a bi-metal plating to ensure corrosion resistance and provide salt spray resistance requirements outlined in MIL-STD-810 standards. FITS connectors meet IAW MIL-PRF-39012 requirements for cable retention and performance, as well as MIL-STD-202 vibration and shock resistance specifications.

The FITS products provide a next-generation level of ease and reliability for shipboard RF applications with the best field performance in the market yet. To learn how well these connectors work, request a free FITS kit.

Electronic Warfare Systems

Electronic warfare systems are responsible for numerous mission-critical applications, including defending ships against attacks and providing enhanced situational awareness. These systems use RF signals to locate and identify potential threats, landscape features and more, and include ground radar, anti-missile defence, guidance systems and similar applications. Every one of these applications depend entirely on continuous transmission of data in real-time with perfect accuracy.

Therefore, phase is a key parameter for detection and measurement in many shipboard RF systems. It must be accurately controlled in the components within those systems, such as coaxial cables and connectors. For example, the electronically steered antennas used in these applications include an array of radiating elements that vary the phase relationships so they can switch from a search radiation pattern to a tracking radiation pattern, or shift direction very quickly. All these elements are fed by transmission lines; and accuracy depends upon the phase relationships between those cables. As a result, the use of phase-stable cable assemblies is increasingly important in today’s sophisticated electronic systems. Times Microwave Systems often works with system integrators and designers to develop phase-matched assemblies.

Environmental Challenges Affecting Phase Stability

At sea, systems are exposed to extreme and highly variable conditions, such as heat or cold and corrosive salt spray. RF signals must travel through the coaxial cables at consistent speeds regardless of these environmental factors. Therefore, phase stability is another key challenge for selecting the right coaxial cables and connector solution.

As temperatures change to cold or warm extremes, the cables do not exactly track together; the phase match degrades just slightly. That small amount of degradation, known as its phase tracking characteristic, can adversely affect antenna performance. Therefore, cable assemblies that are optimised for phase performance are also required to minimise phase change over temperature. For shipboard applications, they should also be low-loss, flexible, low smoke cables with superior stability.

Times Microwave offers PhaseTrack® Low Smoke (PTLS) cable assemblies designed to meet these phase requirements and low smoke zero halogen demands. They feature a proprietary foam polyethylene blended dielectric called TF5. This innovative material provides exceptional phase temperature performance up to 85°C and does not present the abrupt shift in phase that occurs with solid or tape-wrapped PTFE-based products. Times’ PTLS assemblies offer superior stability and eliminate the PTFE ‘knee’.

Offered as a complete assembly, the PTLS family of products are available from sizes 0.2 to 0.6 inches. They address all frequencies ranging from HF through K band and including an optimised version for minimum loss in Ku band. As with the LLSB line, these cables have a low /zero smoke, zero halogen jacket, the same used on Times’ QPL M17 cables.

To meet the demands of a variety of systems, these assemblies are available in a variety of connector interfaces. Times’ PTLS products can be fitted with Times universal intermediate sections; hundreds of front designs are available for most applications including industry standard interfaces such as TNC, N, SMA, SC and HN, among others, or contacts that are compatible with Times M8, V8 and MMP multiport connection systems. The cables can also be terminated with low PIM 7-16, 4.3-10 or N designs and tested to a assure maximum level -160 dBc.

Conclusion

Whatever purpose they serve, shipboard RF systems must be designed to withstand the rigors of the environment in which they will be used – with extremely high performance for mission-critical applications. Low smoke/zero halogen and phase stable cable assemblies are crucial to fulfill these needs. Critical safety requirements can be met with the right cables like Times Microwaves’ new, expanded line of low-smoke, zero halogen PhaseTrack® Low Smoke (PTLS) microwave cable assemblies.

It is also essential to ensure absolute reliability of these systems to work perfectly even in the challenging scenarios that are inherent in maritime applications. When designing RF systems for naval and shipboard applications, be sure to work with a supplier that offers a range of different technologies and can provide customised options for a solution that is optimal for a specific application.

For decades, military and naval communities have turned to Times Microwave Systems to help solve their toughest mission-critical challenges. Our unparalleled experience developing high-performance coaxial cables, connectors and cable assemblies ensures every product meets the most stringent regulatory requirements.

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