A previous radiating element for series-fed arrays proposed by the authors and based on a Cavity-Backed Slot (CBS) is modified to improve its bandwidth. In order to do that, the slot is modified to reduce its resonance frequency so the slot starts radiating at lower frequencies. The modification consists in increasing the effective length of the slot by bending it towards its sides. The concept is proved through the simulation of an already proposed structure with and without the modification. This method successfully reduces the resonance frequency of the slot about 1 GHz in the 5 GHz band, increasing the working bandwidth by this amount. The radiation properties of the element are not altered by this modification.