Background:
RF coaxial connectors are typically regarded as components that are attached to cables or installed on instruments, serving as electrical connections or separators in transmission lines, primarily functioning as bridges. Compared to other electronic components, the history of RF connectors is relatively short. The first RF connector, the UHF connector, emerged in the 1930s. During World War II, driven by the urgent needs of the war, and with the development of radar, radio, and microwave communications, medium-sized series connectors like N, C, BNC, and TNC were developed. After 1958, smaller products like SMA, SMB, and SMC appeared. In 1964, the U.S. military standard MIL-C-39012 for RF coaxial connectors was established, marking the beginning of RF connectors’ development toward standardization, series production, and universal use.
Current Market Development:
With the advancement of high-tech fields such as wireless communications, aerospace, and military technology, the demand for RF connectors has risen significantly, driving rapid advancements in RF connector technology. In recent years, both the quality and quantity of RF connectors have seen breakthrough improvements. New small, miniature, high-frequency, and high-performance products like K-type, V-type, SSMA, SSMB, and OSSP connectors have been developed and introduced to the market. Some developed countries have already produced RF connectors that operate at frequencies up to 110 GHz.
The key technologies for high-end RF connectors are controlled by manufacturers in the U.S., the UK, and France, where their design, production, testing, and usage technologies have become highly refined. A complete standard system has been formed, and materials, auxiliary materials, testing systems, assembly tools, and other components are standardized and produced on a large scale.
Development Trends of RF Coaxial Connectors:
Miniaturization and Microminiaturization:
As electronic devices continue to move towards smaller and more integrated designs—such as smartphones, tablets, and wearable devices—there are increasingly strict size requirements for RF coaxial connectors. For instance, the emergence of SSMP and 3SMP ultra-miniature coaxial connectors meets the space requirements of compact electronic systems, enabling high-density installation and saving more space for portable devices and aerospace applications, where space is crucial.
Modularization and Integration:
Advances in wireless communication technology have led to higher integration of complete systems, with internal structures becoming more modular. Blind-mate RF coaxial connectors and "board-to-board" RF connectors have emerged to solve the interconnection challenges in densely packed spaces, which traditional cable assemblies could not address. These connectors are increasingly used in wireless system modules. The development of connectors like BMA, SBMA, SMP, and SSMP has further facilitated the modularization of electronic equipment, promoting the integration of high-power, miniaturized, and multi-signal control technologies.
High Frequency and High Precision:
To achieve wider channel bandwidth and higher data transmission rates, operating frequencies of complete systems have been steadily rising. As a result, RF coaxial connectors must support higher operating frequencies, with various millimeter-wave connectors like 2.92mm, 2.4mm, 1.85mm, 1.0mm, and 0.8mm emerging. Their upper-frequency limits have progressed from 40 GHz for 2.92mm connectors to 140 GHz for 0.8mm connectors. As the frequency increases, the tolerance requirements for connector size become stricter, which in turn raises the precision demands for machining, electroplating, assembly, and other processes.
High Reliability:
In special environments such as oceans, plateaus, and outer space, devices and components must have high reliability to withstand harsh conditions. For example, products used in island reef environments need to be highly resistant to environmental corrosion; products for space missions, such as satellite, Mars, and Moon exploration, must meet space environment requirements and have longer lifespans, with characteristics like low-temperature resistance, radiation tolerance, atomic oxygen resistance, temperature shock tolerance, prevention of vacuum discharge and micro-discharges, and resistance to cold welding. These requirements drive continuous improvement in material selection, surface treatment processes, and structural design to enhance the reliability of RF coaxial connectors in extreme environments.
High Power:
In modern defense industries, radars require increased detection range and power, necessitating higher transmission power for stronger signals. This creates a demand for high and ultra-high power transmission in RF connectors and cable assemblies. Additionally, in electronic warfare, high-power microwave weapons are used to emit interference signals, and space exploration missions (e.g., lunar and Mars exploration) require long signal transmission distances, high transmission accuracy, and large data volumes—further driving the need for high-power connectors and cable assemblies.
Low Cost:
With the widespread adoption of 5G networks, the expansion of existing communication networks, and the extensive use of large-scale antenna arrays, there is a growing demand for antennas and connectors. Due to the large quantities of connectors needed, their cost constitutes a significant portion of the total system cost. Therefore, reducing connector costs is essential for the widespread application of these technologies. Companies need to optimize material selection, production processes, and mass production to reduce costs while maintaining performance and quality.
Multi-functionality:
In addition to basic signal transmission, RF coaxial connectors will also incorporate signal processing capabilities such as filtering, phase shifting, mixing, attenuation, detection, and limiting to meet the diverse signal processing needs of different application scenarios.
Low VSWR and Low Loss:
To meet the high-quality signal transmission requirements of applications like weapon systems and precision measurements, RF coaxial connectors must continually reduce voltage standing wave ratio (VSWR) and loss, ensuring stable and accurate signal transmission.