The question is vague. Here is an equally non-specific answer.
Antennas are generally high pass and using a S band antenna at X band will probably result in significant changes in the radiation characteristics.
Some exceptions exist, including Vivaldi's, LPD's and various spirals which often operate over octaves of bandwidth. L to Ku band operation is practical with surprising stability of radiation characteristics. Really broad band antennas were developed in the 60's, and that was before LSD.
Regards,
Azulukit