Increasing the loss in the antenna will increase its bandwidth. The Q, which is inversely proportional to the bandwidth, is the ratio of the reactive impedance of the resonator to the total resistive load. sqrt(L/C)/R, for example.
The resistive load is made up of real resistances but also symbolic resistances such as the radiation resistance and a resistance representing dielectric losses (tan delta). Increasing any of the losses will reduce the Q and widen the bandwidth.