Fig. 1. Far field time-domain waveforms of THz waves generated by photoconductive antennas with different substrate materials illuminated by their respective saturated light flux and biased with the same electric field，the inset shows the full widths at half maximum （FWHMs），and peak electric field intensities of the THz time-domain waveforms in far-field

Fig. 2. Far field spectra of THz waves generated by photoconductive antennas with different substrate materials

Fig. 3. Simulated time-domain waveforms and spectra of far-field THz waves generated by LT-GaAs and SI-GaAs antennas：（a） THz time-domain waveforms； （b） THz spectra

Fig. 4. Time-domain waveforms and spectra of THz waves radiated by three kinds of SiC antennas：（a） THz time-domain waveforms； （b） THz spectra

Fig. 5. Time-domain waveforms and spectra of THz waves radiated by photoconductive antennas with different substrate materials illuminated by their respective saturated light flux and biased by different electric fields：（a） THz time-domain waveforms； （b） THz spectra