This is a SMA Reverse Polarity Connector.
The term “reverse-polarised connectors” is used where, for example, a standard cable plug has a female centre contact instead of a male centre contact. Reverse-polarised connectors are very popular in WLAN applications. These connectors are supplied with a threaded coupling, are vibration resistant and can be used at frequencies over 6 GHz (depending on type). The impedance is controlled at 50 Ω.
Connector designs are available with crimp cable termination. Mating face sealing for between plug and jack (mated) meet IP 68 requirements.