Design of RF Connectors – Integral or Split Structure

A split or multi-piece structure refers to the design of the outer or inner conductor in RF connectors, where the conductor is composed of two or more parts from the interface port to the section connecting to the cable. In contrast, an integral structure means that the outer or inner conductor is designed as a single piece.

In the current RF connector market, N-type connectors and TNC-type pin-contact connectors are designed as split structures by some manufacturers. A few manufacturers also produce 7/16-type connectors in a split design. However, there are no strict regulations in IEC standards specifying whether the conductor should be integral or split; this decision is typically left to the manufacturer based on their production capabilities.

The primary reasons for adopting a split or multi-piece design are often to save material costs or to follow product standard examples. However, to achieve lower intermodulation interference, enhance product performance, and reduce costs, manufacturers may opt for an integral structure instead. When a split design is unavoidable, it is important to increase contact pressure, expand the contact area, or use an interference-fit compression ring to minimize contact resistance.

Cost Analysis of Split Structure (N-Type, TNC-Type)

For N-type and TNC-type products, especially RF coaxial cable products with large-diameter corrugated conductors, manufacturing the contact head and housing separately allows for material savings compared to an integral structure. For products without strict third-order intermodulation (PIM) requirements, this approach is reasonable. However, for products requiring low intermodulation, the split design is not recommended.

Comparison of Integral and Split Structures

Integral Structure reduces the number of parts in the RF current path on the inner surface of the outer conductor, thereby minimizing contact imperfections caused by contact surfaces. This helps lower intermodulation interference and reduce voltage standing wave ratio (VSWR).

Integral Structure allows for faster and more reliable assembly, eliminating additional assembly steps required for split designs. This also reduces the need for specialized assembly tools and associated costs.

Superior Performance: The one-piece machining of the outer conductor ensures better coaxiality, lowers contact resistance, and reduces the impact of coaxial misalignment and high contact resistance on VSWR.

Higher Reliability: The integral structure eliminates inconsistencies in contact tightness caused by improper assembly of split designs, preventing poor contact and contact head detachment, thus improving reliability.

Considering the advantages outlined above and a comprehensive cost comparison, the integral structure is superior to the split or multi-piece structure, especially for designs requiring low intermodulation. In the current RF connector market, integral structures are increasingly being adopted in 7/16-type, N-type, and TNC-type connectors.