KDIA (1640 AM) is a radio station of Baybridge Communications in Vallejo, California. It is a separate entity from the station at 1310 AM that held the KDIA call letters for many years. The 1640 AM frequency was licensed as part of an extension of the AM band in 1998, and adopted the abandoned KDIA call letters then.During the day it uses one of KKSF (AM)-910's towers. It has a separate night transmitter site.