A new type of end-fire antenna element is designed. The unique series-fed monopole has good bandwidth performance. The LCD material is used in the substrate to make the dielectric constant of the substrate controllable. By changing the operating frequency of the element and the dielectric constant of the substrate, the antenna element has the ability of horizontal phase sweep. The symmetrical structure of the upper and lower layers is used to restrain the beam warping caused by the floor. The feasibility of the end-fire antenna element is verified by modeling and simulation. In this way, the series-fed antenna is easy to realize the miniaturization and thinning of the antenna. It has good conformal ability and is suitable for airborne platforms with high-speed motion.