A reconfigurable antenna based on a solid state plasma S-PIN diode is designed, which uses a plurality of S-PIN units instead of metal as the radiator. In one excitation mode, the antenna acts as monopole antenna; in another excitation mode，the antenna is radiated as dipole antenna. The antenna achieves frequency reconfiguration from X band to Ka band, which means that it can work well both in X band and Ka band. The two frequency bands have wide range of applications. It can also be applied to some occasions requiring frequency reconfiguration in wide frequency band.