A Parallel Folded Dipole Antenna With an Enhanced Bandwidth for 5G Millimeter-Wave Applications

In this communication, a planar folded dipole antenna array with wide operating bandwidth and compact size is proposed for 5G millimeter-wave (mmWave) applications. The basic antenna element is a pair of parallel folded dipoles (PFDs) connected at the terminals. Compared with a single half-wavelength dipole, the PFD can achieve a flatter impedance curve in the working frequency band, and it is easier to achieve broadband impedance matching with 50-
$\Omega $
feeding line. Moreover, a coupling slot feeding method is adopted to feed the proposed antenna element. The capacitance provided by the coupling slot can counteract the inductance caused by the PFD, thus improving the impedance matching at the low-frequency band. Benefiting from the innovative design, the proposed antenna element can achieve an ultra-wide impedance bandwidth of 64% and a compact size of
$0.26\lambda _{0} \times 0.28\lambda _{0}$
. Furthermore, a wide scanning angle with ±50° over wide bandwidth is testified by a
$1\times8$
array using active simulation. For verification, a
$4\times4$
full corporate-fed array is designed based on the proposed element. The measured results prove that the proposed
$4\times4$
array has a −10 dB impedance bandwidth of 65% covering 17–33.75 GHz and a peak gain of 17.5 dBi. The measured total efficiency is from 69% to 82% over the working frequency band. With the merits of compact size, wide working bandwidth, and wide beam scanning angle, the proposed antenna is a good candidate for mmWave wireless communications.