We analysis, design, and characterization of three prototypes of photoconductive antennas namely Grischkowsky (H-shaped dipole) (Auston switch dipole), an I-shaped (stripline dipole), and a bowtie photoconductive antenna.

A "hybrid" numerical and analytical procedure for estimating the currents induced on the antenna and in the gap, when operating in the reception, is also discussed. The experimental results, which was obtained by a THz time-domain spectroscopy system, show different spectral detection responsivity and agree with the theoretical prediction.

The experimental results show that the I-shaped and bowtie-shaped antennas could detect THz signals at low-frequency regions below 0.6 THz with a much higher sensitivity than the H-shaped antenna. Therefore, these two antennas could be promising for the sensitive room-temperature detection of THz radiation in the low THz frequency region or in THz wireless communication systems.

The observed detection peak frequencies of the I-shaped and bowtie-shaped antennas possessing very long dipole arms indicate that the lowest limit of the frequency detected in a typical THz-TDS using a GaAs photoconductive antenna as emitter/detector is around 0.2 THz which has not been stated elsewhere.

This study provides a good recommendation in THz output power improvement by tuning the frequency response of the antenna toward the frequency response of the photoconductive material for an enhanced coupling of THz radiation to antenna.