What is an SMC Connector?

SMC connectors are a type of coaxial RF connectors that share the same interface dimensions as SMB connectors, but SMC connectors feature a threaded mating design.

SMC connectors are available in both 50 ohm and 75 ohm impedance versions. Typically, 50 ohm SMB connectors are specified for frequencies up to 4GHz, while 75 ohm SMB connectors are specified for frequencies up to 2GHz.

SMC connectors are originally designed with female contacts in a male body or male contacts in a female body. SMC connectors are particularly suitable for mobile applications due to their low VSWR.

Mechanical Feature:

SMC male

  1. The coupling nut features an inner thread of 10-32UNF-2B.
  2. It uses a female center contact.
  3. The insulator completely surrounds the female center contact for 50 ohm SMC male connectors.
  4. For 75 ohm SMC male connectors, part of the female center contact is not surrounded by the insulator, creating an air gap between the female center contact and the outer contact.

SMC female

  1. The body features an outer thread of 10-32UNF-2A with an outer diameter about 4.0mm.
  2. It uses a male center contact.
  3. The insulator snugly fits against the outer contact throughout for 50 ohm SMB female connectors.
  4. For 75 ohm SMB connectors, the amount of insulator is reduced, creating an air gap.

How to judge SMC connectors’ feature from outline:

SMC connector – Male/Plug

The coupling nut has thread inside and the hex coupling nut normally has Hex. 6.35mm.

SMC male connector, 50 ohm V.S. 75 ohm

SMC connector – Female/Jack

There is a smooth area with a diameter of 3.65mm and a length of 3.0mm before the outer thread on the SMC female connector.

SMC female connector, 50 ohm V.S. 75 ohm

SMC connector right angle type

The cable entry or PCB termination is oriented at 90 degrees relative to the coupling direction.

SMC connector straight type

The cable entry or PCB termination is oriented at 180 degrees relative to the coupling direction.

SMC connector bulkhead type

When the thread length exceeds 3.5mm, the additional threads are used for mounting the SMC connector on a panel using a washer and nut. This type can be defined as a bulkhead SMC connector.

Rear mount type bulkhead
The SMC connector in rear mount bulkhead type is inserted through a panel mounting hole from the internal side of the device towards the external side. It is then secured with a washer and nut from the outside.

Front mount type bulkhead
The SMC connector in front mount bulkhead type is inserted through a panel hole from the external side of the device towards the internal side. It is then secured with a washer and nut from the inside.

SMC connector male/female PCB connector

PCB type SMC connectors normally have leg lengths of 2.9mm or 3.9mm. Four legs and one conductor go through the PCB vertically and are soldered on the rear side of the PCB.

SMC connector edge mount

An SMC edge mount type connector will be mounted on the PCB from the board's edge.