We report on continuous-wave optoelectronic terahertz (THz) measurements using low-temperature grown (LTG) GaAsSb as photomixer material. A broadband log-periodic antenna and a six interdigital finger photomixer with 1 µm gap is fabricated on LTG-GaAsSb for THz generation and detection. At 0.37 THz, the resonance frequency of the inner most antenna tooth, we obtained a power of 6.3 nW. A Golay cell was used as detector. The photocarrier lifetime of the material was determined to be 700 fs by pump-probe experiments with an optical wavelength close to the band gap of LTG-GaAsSb. The band gap was 1.0 eV, measured by wavelength dependent pump-probe measurements.