Leaky Characteristics of a Channel Guide Antenna Filled with Left-handed Material
A new leaky wave antenna based on channel guide filled with left-handed material (LHM), operating in evanescent surface mode of TM polarization, is presented for millimeter wave applications. A transverse equivalent network that yields a dispersion relation in closed form is employed to analyze the leakage characteristics of the antenna. The frequency dependences of the leaky characteristics for the present antenna are given, from which the backward radiation is clearly demonstrated. Figure 1 shows the cross section of the leaky antenna. Fig. 2 shows the frequency dependence of the propagation constant of the present antenna. The curve in Fig. 2(a) is actually the ω-β diagram, from which the group velocity (υg=(θ)ω/(θ)β) and phase velocity (υp=ω-β) can be inferred. It is shown that during the frequency region 47.6-48.2 GHz (In this region, ε(ω)μ(ω)> 1 and |ε(ω)|< 1, thus the TM evanescent surface mode exists), υg and υp are always anti-parallel (υpυg < 0) for TM evanescent surface mode, which indicates that the mode is of left-hand property, therefore the antenna should be of backward radiation. Contrary to the antenna filled with RHM, as the frequency increases, the phase constant β of the present antenna becomes smaller. That is to say, the field decays more slowly when it leaves away from the air-dieffectric interface and more fields distribute in the air region. As a result, the leakage goes up, which is clearly shown in Fig. 2(b).
Yongmei Pan Shanjia Xu
Department of Electronics Engineering and Information Science University of Science & Technology of China, Hefei 230027, China
国际会议
Progress in Electromagnetics Research Symposium 2007(2007年电磁学研究新进展学术研讨会)(PIERS 2007)
北京
英文
142-143
2007-03-26（万方平台首次上网日期，不代表论文的发表时间）