In this research, we present an optical transparent patch antenna fabricated with poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS; PP). This patch antenna provides a peak gain at 2.45 GHz. The parameters of the patch antenna are designed on the basis of the transmission line theory. Vector network analyzers can be used to obtain a wide gap of the patch antenna, i.e., a low resonance frequency. In this study, the average transmittance of the patch antenna is higher than 88%, which is measured by ultraviolet–visible (UV/Vis) absorption spectroscopy. To increase the conversion efficiency of the patch antenna, a PP film is annealed at 220 °C to improve the conductivity. The higher the conductivity of the film, the higher the conversion efficiency of the patch antenna. The sheet resistance is increased from 216 to 80 Ω/sq. The results of S11= −16 dB, gain = −8.6 dB, and efficiency = 7% are obtained using vector network analyzers and by antenna radiation pattern measurement. The result indicating that annealing improves the efficiency of the transparent patch antenna is feasible.