RF coaxial connector compatibility upgrade solution

RF connectors play a critical role in microwave transmission systems, serving as essential components for both connection and disconnection. They act as interfaces between various RF circuits, requiring global compatibility and interchangeability to remain relevant. Over the past century, the IEC international standard coaxial connectors have evolved significantly, resulting in hundreds of standardized interface models derived from non-standard designs. With the rapid development of wireless communication, especially in recent decades, RF coaxial connectors have undergone continuous improvements. However, as equipment is upgraded, old devices are gradually replaced, creating new technical demands on RF connectors. These include enhanced electrical performance, mechanical reliability, and environmental resistance—requirements that traditional designs may not meet. This has led to challenges in designing connectors that can seamlessly integrate with both legacy and modern systems. Therefore, the need for compatibility upgrades in RF connectors has become a crucial focus for manufacturers worldwide.

The typical structure of an IEC standard RF coaxial connector is illustrated in Figure 1:

Figure 1. Typical Standard Interface Structure

The socket consists of an outer conductor (11), an inner conductor (12), and an insulating support (13). The plug includes an outer conductor (21), an inner conductor (22), an insulating support (23), a sealing ring (24), and a screw sleeve (25). When the plug is inserted into the socket, the internal thread (251) on the screw sleeve engages with the external thread (110) on the socket’s outer conductor. A mechanical and electrical reference surface (1212) is located at the end of the plug’s outer conductor and the bottom of the socket’s outer conductor, with the sealing ring compressed to maintain a gap (1010a). Despite their widespread use, these traditional RF connectors face several limitations when meeting the demands of modern communication systems:

1. They lack the ability to allow quick insertion and release, leading to inefficiencies during installation, debugging, testing, and production.

2. Modern communication equipment requires strict intermodulation control, which relies on sufficient pre-tightening force. Insufficient tightening or loose threads can cause random intermodulation interference, while excessive force may damage the silver plating on the contact surfaces, increasing contact resistance and reducing signal integrity.

3. In existing designs, the outer conductor is often split but lacks a gap, leading to unstable electrical contact in vibrating environments. This instability can cause signal drift, affecting both intermodulation and return loss performance.

4. During installation, long RF cables are often rotated, causing the tightened plug to resist this movement. This can lead to loosened screws or damaged cables, resulting in system failures or reduced service life.

To address these challenges, this paper introduces a high-compatibility fast-locking RF coaxial connector. Compared to conventional designs, this connector offers dual functionality—supporting both threaded and quick-connect operations. It is compatible with older versions, maintains stable and reliable intermodulation and return loss performance, and prevents thread loosening or cable damage due to rotation. Furthermore, its simple and robust design helps reduce manufacturing costs and improve precision, making it ideal for modern communication applications.

This high-compatibility, fast-locking RF coaxial connector can be implemented in multiple ways. For clarity, we define four distinct solutions: I, II, III, and IV. All options share a common structure, where the socket includes an outer conductor (11a, 11b), an inner conductor (12), and an insulating support (13). The plugs (2a, 2b, 2c) in Solutions I, II, and III feature an outer conductor (21a, 21b, 21c), an inner conductor (22), an insulating support (23), a sealing ring (24), an unlocking sleeve (25a), a compression spring (26a), and a circlip (28a). In contrast, Solution IV features a plug (2d) with an outer conductor (21d), an inner conductor (22), an insulating support (23), a sealing ring (24), and a screw sleeve (25b).

All four solutions share a key feature: the electrical reference surfaces (1212b, 1212c) are electrically connected via resilient contacts (211b, 111b, 211a, 111c). The outer conductors (11a, 11b) are designed with an external thread (110) and a V-shaped groove (111a) in the middle. The outer conductors of the sockets (1a, 1b) are coupled to the front end of the hole, while the outer conductors of the plugs (2a, 2b, 21c) are coupled to the bottom end of the shaft. Both ends are equipped with mechanical reference faces (1212a), ensuring accurate alignment and stable electrical contact.