Abstract: Based on the problems and development requirements of radio wave coverage in confined space, this paper investigates the propagation and radiation characteristics of a novel two-dimensional planar periodic leaky-wave antenna, and uses the ray-tracing method to compute and analyze its radio wave coverage performance in tunnels. This leaky-wave antenna consists of a set of grounded radial concentric metal rings and a center circular patch. A vertical probe is used to feed the antenna to produce the fundamental mode TM₀ mode, with the structural dimensions properly designed. Then the periodic micro-strips on the upper surface will perturb the surface wave to produce leaky wave. The calculation method of the propagation constant and the radiation characteristics are theoretically analyzed, and then verified by simulation and measurement. The results show that the antenna can produce a two-dimensional flat conical beam in the upper half-space. The operating frequency band is 10 GHz with a gain of 2.5 dB and an impedance bandwidth of 19%, and the efficiency is over 90%. When using ray tracing method to calculate and analyze the radio wave coverage, the coupling loss distribution in the tunnel is firstly studied, and the antenna is then set up in different positions with different directions, so as to optimize the setting up position for better radio wave coverage performance. Besides, different combinations of setting up modes are proposed to optimize the radio wave coverage performance in the tunnel. The results show that the coupling loss in the tunnel of the combination system based on the two-dimensional leaky wave antenna can keep around -65 dB, which almost meet the actual requirements of radio wave coverage in confined space. Finally, an actual tunnel is selected for testing, and the results are basically consistent with the theoretical calculations.