I bought a 2.4 GHz antenna on eBay. It's a 180° sector antenna that I want to use for Bluetooth. Could anyone tell me what this connector is? The manufacturer is no longer operating so I can't consult their website. I don't think it's BNC because the female BNC connectors I see would not screw onto the outside and this connector has outside threads.

 

Perhaps: https://en.wikipedia.org/wiki/N_connector

 

Perhaps: https://en.wikipedia.org/wiki/N_connector

Trans-gender RF connector.

 

It looks like a reverse-polarity(RP) N connector, often used by wifi ISP's in their equipment. RP-N is a typical female N connector but with a pin in it instead of the center socket, and the male plug has the female pin in it.
You can buy RP-N to regular N adapters, usually on Ebay....
Or, buy the RP-N male connector and attach it to your cable. I actually have some RP-N LMR-400 cables with N male connectors on them - I cut those off and install regular N connectors.
That said, what is under the shrink wrap on that connector? Maybe it is an adapter already??

 

Thanks for your responses. I've removed the covering (it was thicker than heatshrink I've encountered in the past) and taken another photograph. I'm not sure it's possible to remove the lower section but it does seem to rotate. Rotating it does not unscrew it and I'm concerned that I might twist some connection inside that isn't meant to be twisted. Do you think it looks like an adapter?

 

It does look like an adapter. The center knurled part is what should rotate to unscrew the adapter from the upper connector. They may have put it on with pliers or something, so it may be real tight. Don't force it however, and keep the top part from rotating if trying to remove the "adapter"
Whether the knurled part is part of the upper connector (adapter is double female), or part of the lower adapter (male to female adapter) is hard to tell from the picture. You have to assume either, and test the rotation of the center part both ways (CW and CCW).
Based on the picture, my guess is the knurled part is part of the lower adapter, as only threaded parts are seen on the antenna side. Unscrew it counter clockwise (top rotates to the left in your picture). But, that is just a guess.

 

You were right, it was an adapter. I had to use a pipe wrench and vice grips in order to remove it - there was some kind of glue on the threads. Now I have what I think is a regular female N connector. Thanks very much for your help!

 

"Regular" N connector... Watch out, there is 50 Ohm and 75 Ohm types. And I never found the way to tell one from the other...

 

"Regular" N connector... Watch out, there is 50 Ohm and 75 Ohm types. And I never found the way to tell one from the other...

Thanks for the heads-up. The model is RBTES-BG-S06180 and according to this guide https://manualsbrain.com/en/manuals/35392/?page=4 the value is 50 ohms. Interestingly, it also says that the connector is "Rev-N male" which I suppose means "RP-N male" which suggests that the weird adapter was put there by the manufacturer. The picture in the guide looks like an SMA connector though.

Where does the 50 ohms come from? Is that in the cable or the connector itself? I ordered a 50 ohm cable in any case.

 

The intrinsic impedance of 50 or 75 Ohms comes from the dimensional characteristics of the connector.
From Wikipedia:

And mechanical damage can occur mixing them.

 

Very few antennas have 75 ohm N connectors. In fact, I've never seen one in all my years of wifi and RF use in antennas. 75 ohm may be used in some situations with CATV cabling (which is 75 ohm), but all wifi I've seen is 50 ohm connectors. In fact, I don't think there is a 75 ohm RP-N connector, never seen one (I'm sure someone out there will find one and correct me if possible)