This paper is focused on the analysis of the shielding properties of reinforced concrete under impinging highaltitude electromagnetic pulse. The reinforced concrete provides frequency-dependent shielding effectiveness mainly due to the embedded metallic grid rebars. For characterization of the concrete, three different configurations, i.e., concrete, rebar, and combined reinforced concrete, are analyzed in detail. In addition, the electromagnetic properties of concrete are quantitatively analyzed by its frequency dependence, moisture content, and material mixture ratio. According to the obtained results, as the rebar spacing decreases and the rebar diameter is increased, the transmission coefficient is gradually decreased. In particular, for reinforced concrete with built-in double layered rebar, it is possible to obtain a transmission coefficient approximately 40 dB less than that achieved by single rebar.Index Terms-High-altitude electromagnetic pulse (HEMP), metallic rebar, reinforced concrete, shielding effectiveness.

The electromagnetic topology and the BLT equation has been used as useful techniques to analyze coupling effects of huge devices. But in the case of systems including complex parts, applying the BLT equation can be difficult to manifest the complex parts with analytic solutions. To resolve this problem, a numerical method can be used to parts of the whole system in advance. In this paper, a microstrip line filter is analyzed using the BLT equation combined with numerical solutions. Consequently, achieved graphs from the BLT equation show good agreements with graphs obtained using a numerical method only.