An antenna with improved radiation efficiency is provided. The antenna includes an antenna array proximately coupled to a feed line. The antenna array includes a plurality of resonating lines. Each resonating line includes a plurality of axially aligned resonators. The resonators have a resonating surface. The resonating surfaces of the resonators at the ends of the resonating lines are larger than resonating surfaces of the resonators in the middle of the resonating lines. Power is supplied to each resonating ling through a feed line. Electrical field is uniformly distributed along the antenna array so as to improve the radiation efficiency of the antenna.