Full wave simulations of light rail transit cabin with 2.4 GHz Wi-Fi antennas are performed to analyze the signal quality inside the cabin from different access point antenna configurations by using electric field distribution analysis. Since the vehicle is electrically large with a size of 92λ, method of moments with higher-order basis functions and parallel computation is used for accurate and efficient computation. Two types of antennas are used and compared, including an omni-directional monopole antenna and a directional suspended plate antenna. The results of the simulations are analyzed and it is shown that the directional antenna can provide a more homogeneous field distribution.