Broadband Dipole Antenna with Extremely Compact Feeding Structure

A broadband dipole antenna with extremely compact feeding structure is proposed in this paper. By introducing a double-layer slot line structure to avoid using traditional λ/4 balun, the total size of feeding line become much smaller than the antenna itself. As a matching branch is introduced on the top of the dipole, its impedance bandwidth is widened. Measured results show that the reflection coefficient of the proposed antenna is lower than -10 dB from 2.8 GHz to 5.0 GHz and the radiation pattern in this band is omnidirectional.