The loss of large long-wave antennas mainly comes from the ground loss resistance. Laying a grounding wire under the antenna to improve the ground conductivity is an effective way to improve radiation efficiency of long-wave antennas. However, due to various reasons, the grounding grid of long-wave antennas cannot be completely buried underground or laid on the ground, and it is necessary to partially overhead the grounding grid. Traditional analytical methods cannot analyze the impact of overhead grounding on the electrical performance of antennas, and can only use approximate equivalent methods for calculation, resulting in significant calculation errors. This article uses a full wave simulation calculation tool based on the method of moments to analyze the impact of partial overhead grounding on the electrical performance of single tower umbrella shaped long-wave antennas, providing important guidance for the implementation of long-wave antenna engineering and maintenance of grounding grid.