A tunable CW-THz system with a LTG-GaAs based THz source, which consists of an interdigitated finger photomixer integrated log-periodic antenna, is presented. The performance is compared against that of several other broadband CW-THz systems with LTG-GaAs based emitters, incorporating bow-tie and log-spiral antenna geometries. This comparison shows that our maximum output THz power level is within an order of magnitude of that of the state-of-the-art. (C) 2004 Elsevier Ltd. All rights reserved.