MODE DISTINCTION AND RADIATION-EFFICIENCY ANALYSIS OF PLANAR LEAKY-WAVE LINE SOURCE

Using the first microstrip-line higher order mode as an example, mode distinction and radiation efficiency of leaky-wave line sources in the radiation region are presented in this paper, The spectral-domain app roach is used to calculate complex power hows, leaving the line source in the transverse directions and those guided down the line source. P ly observing the behavior of these complex power flows in different fr equency regions, the leaky-wave line source can be distinguished into the antenna mode and the reactive mode in the radiation region, Experi mental results are shown to confirm this mode distinction, Moreover, b y comparing the power carried away by the surface and the space waves, radiation efficiency of the first microstrip-line higher order mode o f various structural parameters is analyzed. The microstrip line is mo re efficient as a leaky-wave line source when its substrate is thin, t he dielectric constant of the substrate is low, and the antenna main,c am is away from the end-fire direction.