What are RF Connectors : A Ultimate Guide

RF connectors also require RF coaxial connectors, which are components that connect coaxial cables, PCB, or other RF transmission lines. This article is a complete guide to RF connectors, including what is RF connectors, history and trends, types, how to choose RF connectors, considerations and so on.

 

What are RF Connectors

An RF connector, also known as an RF coaxial connector, is a component mounted on a cable, PCB, or instrument to connect the electrical parts of a transmission line to or from it.

History & Future Development of RF Connectors

History of RF connectors:

  • In 1930, the UHF connector was born. It is the predecessor of the RF connector.
  • In 1958, there appeared SMA, SMB, SMC and other miniature connectors.
  • In 1964, the American military standard mil-c -39012“RF coaxial connector general specification” was born, RF connectors began to standardize, serialization and generalization. 

Trends in RF connectors:

  • Miniaturization. With the miniaturization of the whole system, the volume of RF connector is required to be smaller and smaller to meet the needs of development.
  • High frequency. Although most products use frequencies between 10 and 40 ghz, HP has introduced 110 ghz RF connectors to develop high-frequency RF connectors for more applications.
  • Multipurpose. Connectors are no longer just bridges, but will be more popular if they can also process signals.
  • Low standing wave, low loss. Some military engineering and precision measurement require low standing wave and low loss connectors.
  • High capacity, high power. With the development of 5G, even the arrival of 6G, it is necessary to develop large-capacity and high-power RF connectors.

 

Types of RF Connectors

Categorize by size

  • Standard: UHF, N, 7/16,7 mm;
  • Small: BNC, TNC;
  • Microminiature: SMA, SMB, SMC, MCX, BMA, SAA, 3.5 mm;
  • Miniature: SSMA, SSMB, MMCX, 2.4 mm, k (2.92 mm) , 1.85 mm, 1mm.

 

Classification by interface structure:

  • Thread type. It is mainly used in test equipment, military and telecommunication equipment, such as SMC, SMA, TNC, N, UHF, 7/16 and 4.1/9.5
  • Push-in type. The combination and separation are convenient and reliable. Such as MCX, SMB series;
  • Bayonet type. Easy to plug and unplug, used in testing and military equipment, such as BNC, MHV series;
  • Push in self-locking. Unique self-locking mode, most of the small high-density connectors. 1.0 mm, 2.3 mm, 1.6 mm, 5.6 mm series;. Slide-in. Commonly used in PCB, applied in different DIN multi-segment connectors.

According to the end of the way: 

  • Connector mil-c-39012;
  • Adapter MIL-A-55339(GJB680)
  • microstrip with banded line ML-C-83517(GJB976)

 

By function:

  • General purpose (Class 2)
  • Precision (Class 0,1)
  • Special Purpose (radiation resistance, high pressure resistance, waterproof, etc.)
  • Multi-function Type (including filtering, phase modulation, mixing, attenuation, detection, limiting, etc.)

 

Technical parameters of RF connectors

  • Impedance. Most RF connectors have an impedance of 50 ohms and some have an impedance of 75 ohms.
  • Voltage standing wave ratio (VSWR) , generally 1.5 or less, the lower the VSWR, the better
  • Frequency Range. Different connecting devices require different frequencies.
  • Insert loss, usually within 0.1-0.5 DB;
  • Echo loss, this is more intuitive than VSWR;
  • Iull-plug frequency, directly affect the service life of RF connectors.

 

 

Construction & Materials of RF Connectors

RF connector structure:

  • Contact. The connector completes the electrical connection function core component;
  • The insulator. Also known as the base or mounting plate. Arrange the contacts according to the required position and spacing, and keep the insulation performance of the contacts and the shell.
  • The shell (depending on the variety) , that is, the outer cover of the connector, easy to fix; 4. Accessories. Structural accessories and installation accessories.

 

Materials for RF connectors: 

  • External conductor: Passivation of stainless steel, gold plating of copper alloy, nickel plating of copper alloy, ternary alloy plating of copper alloy, etc.
  • Inner conductor: copper alloy gold plating, copper alloy silver plating and so on;
  • Insulation support medium: PTFE, PEI, LCP and so on.

Advantages of RF connectors

  • Improve the production process: RF connectors simplify the assembly process of electronic products, but also simplified the process of mass production;
  • Easy maintenance. If electronic components failure, you can quickly replace the RF connector;
  • Easy to upgrade. With the development of RF connector technology, it is necessary to replace the advanced RF connector for better performance.
  • Engineers use RF connectors for greater flexibility in designing and integrating new products.

 

Application Fields of RF Connectors

Radio frequency connectors are widely used:

  • Automotive, communications and communication networks;
  • Safety systems, traffic detection systems;
  • Medical machinery, instrumentation;
  • Aerospace, civil aviation, defense and military;
  • Consumer electronics, microwave components.

How to Choose the Right RF Connector

  • select the actual use of the frequency range.
  • RF connector standing wave ratio should be small.
  • IM requirements, to consider the RF connector material and coating.
  • The selected RF connectors match the electrical impedance of the dispenser.
  • Thread type is better than snap type and push-pull type.
  • The smaller the insertion loss, the better.
  • In general, straight RF connectors perform better than curved ones.
  • If the RF connector meets the requirements, there is no need to pursue high performance RF connectors.

 

Considerations for installing RF connectors

  • Choose the right RF connectors and professional installation tools.
  • Be careful not to cut off the central conductor or insulator when stripping the cable.
  • Follow proper RF connector installation techniques to remove any dirt or debris and ensure good electrical contact.
  • Seal to prevent moisture, dust or other contaminants from entering the connector and causing damage.
  • Check the test. Test the contact resistance, insulation resistance and medium voltage resistance after installing the RF connector.

 

Frequency Range Chart of RF Connector 

 

RAQs

1、Is there any loss in the RF connector?

Loss is a very important index of RF connectors. In general, losses in the frequency range of 0.1-0.5 db, if beyond this range, is not qualified RF connectors.

2、From which aspects to judge the quality of RF connectors?

  • Appearance modeling, coating inspection.
  • Connector structure, mechanical strength, interchangeable state, thread fit;
  • Performance parameters. Loss, impedance, number of pull-ups, etc. .

3、What is the difference between RF Connector and  RF Adapter?

RF connectors are used to connect PCB boards and cables to other devices. RF adapters are used to change gender or as a protection program for connectors, and are also used to connect two RF connectors that would not otherwise be directly connected. Therefore, the RF connector and the RF adapter are two different products, but often used together.

4、How to customize RF connectors?

Product iteration, there are higher requirements for RF connectors, standard connectors can not meet your requirements, it is necessary to design a new custom RF connector. Modify its structure and parameters to match your needs while maintaining quality.

 

Conclusion: This is the complete guide on RF connectors, I hope to help you. If you have more ideas about RF connectors, Welcome to communicate with us by email.

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