An innovative and cost-effective procedure for building multi-layered planar antennas is presented. The antenna is constructed by defining copper patterns forming the feed plane and the antenna plane on a single flexible polyimide substrate and by folding the flex around a low εr and low-loss spacer. By a suitable choice of transfer tape to assemble the different layers, a high alignment accuracy and low substrate losses are ensured. To illustrate our new approach, the design and manufacturing of a coplanar-waveguide aperture-coupled patch antenna covering the complete 2.45 GHz ISM band is described. By means of reflection and transmission measurements, the high gain and high efficiency of the antenna prototypes are demonstrated. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1071–1074, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22355