A design approach to multimode resonant, backfire dipole antenna with nearly equal E-/H-plane patterns is proposed in this letter. The antenna is comprised by a 1.5-wavelength sectorial dipole, a hyperbola-intersected elliptical primary reflector, and an elliptical subreflector. By adjusting the size and shape of the intersected-hyperbola elliptical reflector and the position of the tangentially loaded stubs, the nearly equal E-/H-plane bandwidth (i.e., equal-beamwidth bandwidth) of the antenna can be manipulated to coincide with its impedance bandwidth. As has been validated, the antenna exhibits an octave impedance bandwidth from 1.61 to 3.26 GHz (67.8% for |S| < −10 dB), which is identical to its equal-beamwidth bandwidth. The average half-power beam width is around 63°/65° in E-/H-plane, and the average backfire gain is 8.8 dBi.