Abstract: The present invention relates to the field of antennas and specifically to broadband antennas. Planar low-profile antennas over high-impedance surfaces show improved performance compared to that over metal ground planes, but these high-impedance surfaces often operate over narrow bandwidths because current approaches to the design of high-impedance substrates typically employ identical unit cells with the same resonant frequency to produce high-impedance behavior over a relatively narrow frequency range. The present invention provides improved antenna performance over a broader bandwidth through the use of electromagnetic bandgap cells having a size and related resonant frequency that varies with position to the antenna radiating element in order to match the resonance of the element.