This paper proposes a small antenna system (47 mm × 8 mm × 0.2 mm) to be used in a medical mask. The medical mask is composed of a frame and shield. The frame is made of polycarbonate (PC), and the shield is made of polyethylene terephthalate (PET). The author sets two groups of antennas on the upper side of the frame and sets two other groups of antennas on the sides facing away from the face of the shield. The substrates of the four antennas are all FR4 (εr = 4.4, tanδ = 0.02), so the first antenna type is a combination of PC and FR4, and the second antenna type is a combination of PET and FR4. The antenna system has three working frequency bands, in which the reflection coefficient is lower than −10 dB after actual measurement, and its working frequency bandwidth is 2.38–2.62 GHz, 3.38–3.74 GHz, and 5.14–8 GHz, respectively. It can be effectively used in 5G FR1 and Wi-Fi 7 frequency bands and can easily be combined with medical masks of different materials. This antenna system can use Wi-Fi 7 for wireless transmission indoors and use the 5G FR1 frequency band for wireless transmission outdoors, achieving seamless transmission capabilities.