A Wideband Folded Dipole Antenna With Stable Radiation Patterns Under Multiresonant Modes

A novel wideband folded dipole antenna (FDA) with stable radiation patterns under multiresonant modes is proposed in this communication. First, by lengthening and widening the driven strip of an FDA, the input resistance of its 1st- and 3rd-order modes declines significantly. Second, the driven and non-driven strips are further widened at a fixed ratio to achieve better impedance matching. Third, a pair of open-slot loops (OSLs) is advisably added to compress the resonant frequency of the 5th-order mode close to that of the 3rd-order mode for bandwidth improvement. Finally, a prototype is fabricated to provide experimental verification of the idea, and measured results show that the proposed FDA has a bandwidth of about 82% from 1.72 to 4.10 GHz, which exhibits a good agreement between measurement and simulation. In particular, the proposed FDA obtains stable radiation patterns in the entire operating band.