An energy delivery device for treating a patient includes a probe body and a plurality of elongate electrode elements that extend radially away from the probe body when deployed into tissue of the patient. The electrode elements are adapted to receive electrical treatment energy such as irreversible electroporation (IRE) pulses from an energy source. In one embodiment, each electrode element has a longitudinally varying electrical resistance at the electrode-tissue interface along the electrode so as to provide a uniform electric field along the length of the electrode. The uniform electric field allows a more uniform ablation of tissue within a treatment zone.