German surname Segate

Any suggestions on how to figure out this surname of my ancestor Frederick "Fritz" Segate? According to a record (census I believe) he come's from Mittelbach Sachsen, Germany, born abt 1840. Married Augusta Spore?? (listed in many records as Spore) and migrated to US in 1873 and 1874. Augusta and children came in 1874 using the last name Sagathe. No record of Fritz coming over, but supposedly arrived 1873. The family records are usually using Segate. I've looked at every other spelling I can think of and looked through some German and Sachsen area surnames, but it's a mystery to me as to what the German name actually was if not Segate or Sagathe. Thank you for any suggestions that may lead me in the right direction.