One used Berkeley Varitronics Systems  2.4 GHz Direction Finding Antenna. 

The antenna is missing the SMA antenna used to connect to other hardware, but those cables are cheaply available online in lengths that may be selected to suit your project needs.

This antenna appears to be from a Berkeley Varitronics BumbleBee Multi-Band Spectrum Analyzer 900MHz/2.4GHz/5GHz.

The items is sold as is with no returns, as I have no means of testing it.