A Monopole Antenna Made of a Transparent Conductive Film

As mobile wireless communications have progressed dramatically in recent years, many mobile terminals are becoming smaller and smaller and miniaturization of the antennas employed in mobile devices is required accordingly. In this paper, a monopole antenna that consists of one-half of a bow-tie dipole antenna, made of optically transparent conductive thin film and mounted above a ground plane, is investigated. The antenna is designed to work at 2.4 GHz and the radiation element of the antenna is made of several transparent conductive films with different sheet resistivities. It is found that the gain lowering of the antenna varies from 4.4 dB to 0.2 dB at 2.4 GHz, and the efficiency of the antenna increases from 46% to 93% at the same frequency, as the sheet resistivity of the film decreases from 19.8 Omega/sq to 1.3 Omega/sq, respectively. The antenna is analyzed by a wire-grid model based on the moment method. The resistance of the film is taken into account by parallelly loading a resistance on every discretized element. It is demonstrated after that the analyzed results are in good agreement with the experimental ones