Design and analysis for dipole antennas with equal beamwidth and wideband operation

A design for the antenna with equal beamwidths in two orthogonal planes is described. The antenna is mainly composed of a printed dipole fed with a microstrip balun and a rectangular metallic box used as a reflector. The simulated results obtained with HFSS demonstrate that the beamwidths of the antenna in the E- and H-planes as well as the diagonal plane are almost the same within the 10 dB-return-loss bandwidth from 2.3 to 3.3 GHz; moreover, the cross polarization in these planes is lower than −20 dB. The spherical vector wave expansion of the radiated fields of the antenna is used to explain the radiation characteristics. An antenna prototype is also constructed, and experimental data have good agreements with the simulation results.