Does anyone know if this will fit on the SDS100?
If you are referring to
this antenna, then no, it will not work properly on the SDS100. The SMA connector on the scanner itself is recessed into the case, so that an antenna will seat fully, and maintain the weather resistance of the scanner. Also, as it is not seating fully, you'd have a poor connection from the antenna to the scanner.
The SMA to BNC adapter that Uniden ships with the scanner is made to seat correctly, and maintain the water resistance of the case. You'd be better off using the supplied adapter, & getting the BNC version of that, or a different, antenna.