Here we report design, optimization and fabrication of a plasmon-assisted terahertz (THz) photoconductive antenna (PCA) for THz pulse generation at low-power optical pumps. The PCA design combines a high-aspect ratio dielectric-embedded plasmonic Au-grating placed into the photoconductive gap. Antenna structure, Si3N4-passivation of the photoconductor and the Al2O3-antireflection coating are used to further enhance antenna performance. Both the plasmon-assisted and conventional pCAs were fabricated for comparative analysis of their transient photocurrents, THz waveforms and THz power spectra. A superior performance of the plasmon-assisted PCA was confirmed. Thus, depending on the optical pump power, the transient photocurrent and the THz power spectrum were 101-102 and 102-103 times higher, respectively, for the plasmonic PCA. The highest THz power enhancement of 3×103 was observed at low-power optical pumps of < 1.0 mW. These results demonstrate a strong potential of the plasmonic PCA for operation with low-power lasers; thus, opening new opportunities for the development of portable and cost-effective THz spectrometers and imaging systems.