Fig. 1. PCA loading bias voltage circuit versions, (a-c) load bias voltage circuit board A, (d-e) load bias voltage circuit board B

Fig. 2. The schematic diagram of the THz-TDS

Fig. 3. GaAs PCA DC bias circuit diagram

Fig. 4. Time domain waveform and spectrum for different inductors in GaAs PCA,（a）time domain waveform for different inductors in GaAs PCA,（b）spectrum for different inductors in GaAs PCA

Fig. 5. Plot of relative radiation efficiency η under different inductors

Fig. 6. Comparison of THz time domain waveform and spectrum with and without the inductor, (a) time domain waveform comparison, (b) THz spectrum waveform comparison