In this paper the design of printed log-periodic antennas is presented. Focus is on the design of an antenna for long range communication within a wireless sensor network system for sea water quality monitoring, but the contents of the paper can also be useful at other frequencies and other applications. The difficulties in using the design procedure for log-periodic dipole antennas proposed by Carrel are discussed and some limitations are pointed out. New design hints are given, and preliminary examples of printed antennas are presented. Simulations are carried out not only for free-space but also in presence of sea and wave motion. Results show that printed log-periodic antennas can be good candidates for the intended application.