THz Propagation Experiment

In this chapter, an example of experimental and analytical investigation of line-of-sight (LOS) reflections in the frequency range of 220–330 GHz at up to 2-m distance for the short-range THz communications systems is presented. To characterize the general behavior of the THz LOS reflections, power delay profiles are measured for various reflector sizes, reflectivities, and link distances with a frequency-domain measurement setup and analyzed with simple formulas. In this example, from the experimental and analytical investigation, it was revealed that, even with small reflectors such as the packaging or housing bodies of the transmitter and receiver, the interference due to the LOS reflection that used to be ignored in the THz channel analysis so far is not ignorable and the direct signal to the reflected interference ratio is nearly constant at link distances shorter than a certain threshold. As the distance increases above the threshold, the LOS reflection signal abruptly disappears and finally becomes ignorable. In addition, the dependency of the threshold distance on the antenna gain, and dimensions and reflectivity of the reflecting bodies, will be analytically derived. The observations and results in this example can be used for simulations of signal propagation in future short-range THz wireless communication systems. Further complicated measurement and analysis can be developed based on this example.