AbstractIn this paper, a first investigation on critical issues for a fire‐detection ground‐based Ku‐band radiometer antenna design is addressed. A printed technology with standard dielectrics has been employed, to reach low cost, simplicity in realization, and easy integrability with the electronic front‐end. The antenna has been designed as an array of patches, where number of elements, spacings, and feeding currents has been optimized to fulfill requirements of low side lobe level and good crosspolarization. For the radio frequency front‐end, the receiver architecture is a direct‐conversion topology, because it is well suited to be monolithically integrated in a single chip. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2279–2282, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22649