An improved but simple four band octagonal patch with new slotting technique of making a compact patch antenna is presented, which is suitable for C-band, X-band, Ku-band and K-band applications. This compact microstrip antenna realized by changing the geometric shape, obtained by inserting small circular slots in a new way. The simulation has been performed by simulation software GEMS version 7.71.01 and using Taconic TLY-5 dielectric substrate with relative permittivity 2.2 and height 1.588mm. The simulated return losses are obtained -16.50dB, -17.25dB, -39.22dB and -30.75dB at 7.49GHz, 10.89GHz, 15.70GHz and 20.10GHz respectively. Therefore, this antenna can be applicable for C-band, X-band, Ku-band and K-band applications respectively.