Abstract: The antenna measurement system of the small airborne platform has special requirements for its transmitting source antenna. In order to obtain a broadband and dual-polarized radiation characteristic, a novel dual dipoles antenna with reflection cavity is presented. The crossed dual dipoles share a coaxial feed cable and a reflecting board. A new reflective cavity structure of copper foil and PA6 plate is proposed to meet the weight requirement.The dual dipoles antenna model is built and simulated in electromagnetic software CST. The results show that within test band of 650 ~1 400 MHz the pattern has a good symmetry, the antenna achieves an impedance bandwidth of 73.2% (Voltage standing wave ratio is lower than 2.5) with an isolation between the two ports over 50 dB, the antenna gain is higher than 7 dBi and the total weight of antenna is less than 0.6 kg. Therefore, the antenna meets the requirements of measurement system.