Abstract: In this paper, a fully transparent wideband high-gain ionic liquid antenna is proposed for meeting the practical requirements of optical transparency and stealth camouflage in 5G beautification mobile base station and military optical / microwave multimode composite guided stealth. The antenna is composed of ionic liquids, an ellipsoidal lens container, a conical radiation director, and a reflective ground with a transparent conductive film. Firstly, the frequency non-selectivity on the dielectric lens is used to make the antenna acquire wide-band performance. Secondly, by using low-loss ionic liquid and ellipsoidal lens liquid dielectric structure, a coherent ray field of the liquid dielectric lens can be produced, which can achieve high directivity. Finally, a conical radiation director is loaded around the liquid dielectric to concentrate the radiation beam and improve the gain. In addition, by introducing a dielectric ground plane with transparent conductive film on the back of the antenna, not only the back lobe is further reduced, but also the whole antenna is optically transparent. Simulated and measured results have demonstrated that the liquid antenna operates the frequency band range of 9. 9 GHz~18 GHz (S11≤-10 dB), and the maximum measured gain can reach 12. 1 dBi. The proposed antenna has wide application prospects in radar detection, 5G base stations, electronic countermeasures, transparent electronic devices and other fields.