Abstract This paper proposes a new elliptical dual-band antenna with a crescent slot with the advantages of compactness, lightweightness, low cost, and easy installation for 5G mmWave applications. The radiating element is obtained by Boolean manipulation of three ellipses of unequal length to short axis ratio, the resulting crescent slot defining its dual-band characteristics. The -10 dB impedance bandwidth of 23.8—31.6 GHz at 28 GHz and a bandwidth range of 36.8—40.6 GHz at 38 GHz are achieved, completely covering the currently applicable n257, n258, n260 and n261 mmWave bands and filtering out the unlicensed 31—36 GHz band. Dimensions of the single element are 10 mm by 7 mm. In addition, to reduce the interference caused by atmospheric attenuation, a conventional feeder network is combined with the designed antenna element to form a 1 × 4 line array to improve the gain. The antenna array with total dimensions of 20 × 25 mm2 is modeled in 0.254 mm thick Rogers 5880 substrate. As a result of the array configuration, 10.4 dBi gain and a 95% radiation efficiency are achieved in the 28 GHz band. Meanwhile, at the 38GHz band, the gain is 10.4 dBi and the radiation efficiency is 95%. The proposed antenna meets the 5G communication requirements well and can be a better candidate in the mmWave band range.