Differential-Fed Magneto-Electric Dipole Antenna With Integrated Balun Based on Ball Grid Array Packaging

This article presents a differential-fed magneto-electric (ME) dipole with integrated balun based on ball grid array (BGA) packaging. The electric dipole consists of four metal patches on the top layer, and the magnetic dipole consists of two rows of plated through-holes (PTH) and ground on the bottom layer. The electric and magnetic dipoles are excited simultaneously by double L-shaped metal probes. In addition, the integrated balun is implemented by a simple 180° delay line that provides a pair of differential signals to the double L-shaped metal probes. The miniaturized size is obtained by the integrated balun and BGA packaging. Antenna elements and $1 \times 8$ fixed beam arrays are carefully designed, manufactured, and validated. The proposed antenna element achieves a compact size of 5 mm $\times 5$ mm $\times1.8$ mm ( $0.47\,\,\lambda ₀ \times 0.47\,\,\lambda ₀ \times 0.017\,\,\lambda ₀$ , $\lambda ₀$ is the free-space wavelength at the central operating frequency of 27.9 GHz). The measurement results demonstrate that the antenna element has a reflection coefficient below −10-dB bandwidth of 17.2% and covers 25.5–30.3 GHz. The antenna element and $1 \times $ 8 array achieve a realized gain of 8.3 and 14.8 dBi, respectively. The proposed antenna elements can be widely applied to the 5G millimeter-wave n257 (26.5 −29.5 GHz) and n261 (27.5 −28.35 GHz) bands.