Due to the limited space of the fairing, HaiYang-2 satellite microwave Calibration Radiometer Antenna (HY-2 CRA) used deployable structure and two hinges to perform the stretching action. Many efforts had been also exerted to meet the demand of high gain, low noise, high beam efficiency, low loss etc. The offset paraboloid made of carbon fiber together with conical corrugated horns was selected for this antenna to reduce the total mass. The working frequencies were selected to be 18.7 GHz, 23.8 GHz and 37 GHz respectively with 600 MHz bandwidth. The new compact two septums Orthomode Transducers (OMT) were proposed and analyzed by full wave method, and these OMT were employed to meet the demand of the dual polarizations for all three frequencies. Finally the whole antenna was tested in the far field testing system. The technical renovation about working mode, key knowledge, design procedure, and measurement were analyzed in this paper.