1. Background
In this era of rapid information development, communication technology has become a key driving force for social progress. From mobile phone communication and internet access in daily life to automation control and remote monitoring in industrial fields, communication cables play an irreplaceable role as the “highway” for information transmission. Among various types of communication cables, coaxial cables, with their unique structure and excellent performance, have always been one of the important media for information transmission.
The history of coaxial cables can be traced back to the late 19th century. With the birth and continuous development of radio communication technology, there was an urgent need for a cable that could efficiently transmit high-frequency signals. In 1880, the British scientist Oliver Heaviside first proposed the concept of coaxial cable and designed its basic structure. After continuous improvement and perfection, coaxial cables gradually gained widespread application in the field of communication, especially in cable television, radio frequency communication, radar systems, and other fields.
However, when we shift our focus to the marine environment, particularly in the fields of ships and offshore engineering, coaxial cables face many challenges in application. The marine environment is complex and variable. During navigation, ships are subjected to various factors such as wave impact, salt spray corrosion, temperature changes, and electromagnetic interference. The special environment puts higher demands on the performance of coaxial cables. Therefore, shipboard coaxial cables have emerged. As a coaxial cable specifically designed for the marine environment, shipboard coaxial cables have stronger shielding performance and can adapt to complex marine environments with strong electromagnetic interference. They can meet the needs of longer transmission distances, provide a larger bandwidth, support high-speed data transmission, and ensure stable and reliable signal transmission even in harsh marine environments.
2. Introduction
Shipboard coaxial cables are high-performance communication cables specifically designed for the marine environment. Their structure and performance have been specially optimized to meet the various stringent requirements of the marine environment. Compared with ordinary coaxial cables, shipboard coaxial cables have significant differences in material selection and structural design.
The basic structure of shipboard coaxial cables consists of four parts: inner conductor, insulation layer, outer conductor, and jacket. This structural design enables coaxial cables to effectively transmit high-frequency signals while reducing signal attenuation and interference.
- Inner Conductor: The inner conductor is the core part of the shipboard coaxial cable, usually made of high-purity copper. Copper has excellent electrical conductivity, ensuring minimal signal loss during transmission. The diameter and shape of the inner conductor have an important impact on the cable’s transmission performance. In shipboard coaxial cables, the diameter of the inner conductor is usually optimized according to specific transmission requirements to ensure stable transmission in the marine environment.
- Insulation Layer: Located between the inner and outer conductors, the insulation layer mainly isolates the inner conductor from the outer conductor to prevent signal leakage and short circuits. The insulation material needs to have good electrical insulation and mechanical properties, as well as characteristics such as salt spray corrosion resistance, high-temperature resistance, and low-temperature resistance to meet the special requirements of the marine environment. Common insulation materials include polytetrafluoroethylene (PTFE) and foamed polyethylene (Foam PE).
- Outer Conductor: The outer conductor is the shielding layer of the coaxial cable, usually made of tinned copper wire braid and aluminum foil. The main function of the outer conductor is to shield against external electromagnetic interference and ensure that the signal is not disturbed during transmission. The design of the outer conductor in shipboard coaxial cables needs to fully consider electromagnetic interference resistance and vibration resistance to ensure signal stability during ship navigation.
- Jacket: The jacket is the protective layer of the shipboard coaxial cable, mainly protecting the cable from external environmental erosion. The jacket material usually needs to have characteristics such as salt spray corrosion resistance, wear resistance, and flame retardancy. Common jacket materials include low-smoke zero-halogen (LSZH) polyolefins and polyvinyl chloride (PVC).
3. Classification
Shipboard coaxial cables can be divided into several types based on different classification methods.
3.1 Classification by Structure
- Single-Shielded Coaxial Cable: The outer conductor consists of a single layer of tinned copper wire braid or aluminum foil, suitable for signal transmission in general environments.
- Double-Shielded Coaxial Cable: The outer conductor consists of two shielding layers, usually including one layer of aluminum foil and one layer of tinned copper wire braid. Double-shielded coaxial cables have better electromagnetic interference resistance and are suitable for environments with complex electromagnetic conditions.
- Armored Coaxial Cable: Based on double shielding, an additional layer of armor, usually made of steel wire or steel tape, is added. Armored coaxial cables have stronger mechanical protection.
3.2 Classification by Transmission Frequency
- Low-Frequency Coaxial Cable: Mainly used for transmitting low-frequency signals, such as audio signals and low-speed data signals. The structure of low-frequency coaxial cables is relatively simple, with a smaller inner conductor diameter and thinner insulation layer.
- High-Frequency Coaxial Cable: Mainly used for transmitting high-frequency signals, such as radar signals and satellite communication signals. The structural design of high-frequency coaxial cables is more complex, with a larger inner conductor diameter and insulation layers usually made of high-dielectric constant materials to reduce signal attenuation and improve transmission efficiency.
3.3 Classification by Application
- Coaxial Cable for Radar Systems: Used for radar signal transmission, requiring high transmission efficiency, low attenuation, and good electromagnetic interference resistance.
- Coaxial Cable for Satellite Communication Systems: Used for satellite signal transmission, requiring high-frequency transmission capability, low attenuation, and good high- and low-temperature resistance.
- Coaxial Cable for Ship Navigation Systems: Used for signal transmission of ship navigation equipment, requiring high reliability, vibration resistance, and salt spray corrosion resistance.
- Coaxial Cable for Ship Entertainment Systems: Used for signal transmission of ship entertainment equipment, such as television and audio signals, requiring good transmission performance and interference resistance.
4. Requirements
Shipboard coaxial cables need to meet a series of special requirements to ensure their reliability and safety in marine environments.
- Salt Spray Corrosion Resistance: The marine environment contains a large amount of salt, and the corrosive effect of salt spray on cables is very strong. The materials of shipboard coaxial cables need to have good salt spray corrosion resistance to prevent cable corrosion and damage during long-term use.
- Electromagnetic Interference Resistance: Various equipment on ships generates strong electromagnetic interference. Shipboard coaxial cables need to have good electromagnetic interference resistance to ensure stable signal transmission.
- Vibration Resistance: During navigation, ships are subject to wave impacts, causing vibration. Shipboard coaxial cables need to have good vibration resistance to prevent damage during vibration.
- High and Low Temperature Resistance: When sailing in different sea areas, different temperature environments will be encountered. Shipboard coaxial cables need to be able to work normally under extreme temperature conditions, generally requiring a working temperature range of -40°C to +70°C.
- Flame Retardancy: In the event of a fire on a ship, the burning of cables can produce a large amount of smoke and toxic gases, seriously threatening the lives of crew members. Therefore, the jacket of shipboard coaxial cables needs to be made of low-smoke zero-halogen materials, meeting the IEC 60332 flame retardancy requirements and the IEC 60754-1/2 and IEC 61034-1/2 low-smoke zero-halogen requirements.
At the same time, in terms of standard specifications, shipboard coaxial cables should pass the strict certification of the International Maritime Organization (IMO) and classification societies (DNV, ABS, CCS, etc.).
Post time: May-26-2025