The usage frequency and power of the commonly used coaxial connectors in the electromagnetic compatibility laboratory

　　Abstract: This paper introduces the commonly used coaxial connectors (joints and cables) in the electromagnetic compatibility laboratory, as well as the maximum operating frequency and maximum allowable power for the use of these connectors, including BNC connectors, N-type connectors, SMA connectors, 3.5mm connectors, 2.92mm/K connectors, and 7/16 connectors.

　　The BNC connector is a snap-fit type RF coaxial connector, featuring rapid connection and reliable contact. It typically has a maximum operating frequency of 4GHz and can withstand a maximum power of 70W (at the highest frequency). The electromagnetic compatibility laboratory extensively uses BNC cables in the low-frequency range, especially in scenarios where cables need to be frequently connected and disconnected, such as in the CE102 test where cables need to be switched between different monitoring ports at different locations. In such cases, BNC cables should be preferred.

Figure 1  BNC connector 

The N-type connector is a threaded connection type of medium-power connector, featuring high reliability, strong vibration resistance, excellent mechanical and electrical performance. The common N-type connector typically has a maximum operating frequency of 11GHz and can withstand a maximum power of 150W (at the maximum frequency); the precision N-type connector generally has a maximum operating frequency of 18GHz and can withstand a maximum power of 250W (at the maximum frequency).

Figure 2 N-type connector 

The SMA connector is a widely used small-sized threaded coaxial connector with long service life, excellent performance and high reliability. The maximum operating frequency of SMA connectors is generally 18GHz, and the maximum power they can withstand is 70W (at the maximum frequency). Due to its structural design, the service life of SMA connectors is only a few hundred times, and they are suitable for applications where connections are not frequent.

图3  SMA连接器

3.5mm连接器尺寸和规格上与SMA一致，不同的是在接头中使用了空气介质，工作频率到34GHz。3.5mm连接器物理接口相对SMA更坚固耐用，可实现数千次重复连接。因其外导体内径为3.5mm，从而被命名为3.5mm连接器。3.5mm连接器一般最高使用频率34GHz，最大承受功率45W（最高频率处）；

　　Figure 4 3.5mm connector

　　The 2.92mm connector is also named K (designated for the K-band which covers the microwave frequency range), because the inner diameter of its outer conductor is 2.92mm, and it is thus called the 2.92mm connector; the 2.92mm/K connector typically has a maximum operating frequency of 40GHz and can withstand a maximum power of 20W (at the highest frequency).

Figure 5  2.92mm connector 

The 7/16 connector is a larger-sized threaded connector with features such as robustness, low loss, and high working voltage. The maximum operating frequency of the 7/16 connector is generally 7.5GHz, and it can withstand a maximum power of 820W (at the highest frequency).

Figure 6  7/16 Connector