A new broadband electromagnetic wave absorber based on a periodic surface and a method to increase its absorption bandwidth is proposed. The proposed absorber structure shows broadband characteristics, and its bandwidth is improved by generating additional resonances through a reasonable approach. To provide an understanding of the logical design procedure, an analytical method to determine the sheet resistance and new equivalent circuit models for analysing the impedance are both presented. From the analysis, it is shown that the exact range of the sheet resistance corresponding to the desired absorption level can be efficiently estimated for the resonance of the structure. For the verification of this approach to obtain an efficient design, as well as the functionality of both the absorber and the proposed method, experimental results are demonstrated along with analytical and computational results. The final measured results using the proposed method show a broadband reflectivity response, with a fractional bandwidth of approximately 93% below -10 dB and a bandwidth increase of 17%.