Читать книгу Introduction To Modern Planar Transmission Lines - Anand K. Verma - Страница 248

Figure (5.15c) shows that the charged particle moving with a velocity V_c (V_c > V_p) in a DNG medium with a negative refractive index −|n|. It creates backward radiation with the negative Cerenkov angle,

(5.5.42)

Figure 5.15 Cerenkov radiation in DPS and DNG media.

Figure (5.15d) shows that the wavevectors and Poynting vectors , for both the upper and lower radiations, are anti‐parallel that causes the backward radiation. Thus, a DNG medium supports the reverse, i.e. inverse Cerenkov radiation. The metamaterial medium could be continuously varied from the DPS to DNG forming the forward end‐fire to broadside to backward end‐fire antenna [J.26, J.27, B.6, B.7]. The inverse Cerenkov radiation has been experimentally confirmed in the microwave frequency range [J.28]. The realization of such a microstrip antenna is illustrated in the subsection (22.4.1) of chapter 22.