The results of studies of the electrical and thermal properties of photoconductive antennas for terahertz-radiation generation are reported; these antennas are fabricated on the basis of low-temperaturegrown GaAs (LT-GaAs) and In x Ga1 – x As with an increased content of indium (x > 0.3). It is shown that the power of Joule heating PH due to the effect of “dark” current in In x Ga1 – x As exceeds the same quantity in LT-GaAs by three–five times. This is due to the high intrinsic conductivity of In x Ga1 – x As at x > 0.38. Heatremoval equipment for the photoconductive antenna has been developed and fabricated. The results of numerical simulation show that the use of a heat sink makes it possible to reduce the operating temperature of the antenna based on LT-GaAs by 16%, of the antenna based on In0.38Ga0.62As by 40%, and for antennas based on In0.53Ga0.47As by 64%.