Very high wind loads represent one of the major problems for the ultralarge-scale 5G base station array at the sub-6 GHz band, where dozens of or hundreds of antennas are used. An ultracompact dual-polarized cross-dipole antenna with an extremely small overall projected area is presented. The array with low wind load is realized by miniaturized cross dipoles and the replacement of the traditional ground plane with a defected ground structure (DGS) and metal mesh reflector. The DGS is utilized to realize size reduction and isolation enhancement. The projected area of the antenna is reduced by 70%. Therefore, each antenna in the array can be independently packaged using a streamlined radome with a low wind load. And the inter-radome spacing is large enough to make holes that are used to further reduce wind load. The antenna prototype is designed, fabricated, and measured for the sub-1 GHz band. The measured results show that the impedance bandwidth is 680-970 MHz, the polarization isolation is higher than 20 dB, and the gain is around 6.5 dBi. It is verified that the proposed ultracompact antenna of high radiation performance is very suitable for an ultralarge-scale array of low wind load in a 5G base station.