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Measurements of the propagation of UHF radio waves in two trapezoidal tunnels are reported. Values of propagation loss in dB/100 m are given. It is found that the propagation attenuates at least 900 MHz. In addition, a portable FM radio system operating at 900 MHz is tested in one tunnel. It achieves a highly intelligible communication range of 230 m.
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Zheng et al. (1999) studied this question.
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