AbstractThis paper deals with the design of circularly polarised patch‐antenna arrays on high‐K material substrates. The use of these materials in combination with an EBG structure to prevent the excitation of substrate modes leads to the possibility of designing scanning arrays without suffering from grating lobes and scan‐blindness limitations. The proposed antenna configuration was used in both a single‐element and an array configuration. Highly efficient configurations together with smooth radiation patterns with low back radiation and high directivities were obtained. The array configuration showed a very broad scanning angle (140°) without suffering from grating lobes. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 527–532, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20524