Millimeter-Wave Wideband ±45° Dual-Polarized Phased Array Antenna Based on Compact Wideband Widebeam Dipole Element Antenna

To meet the requirements of a millimeter-wave (mmWave) communication system prototype complying with 5G (24.25–29.5 GHz) and B5G/6G (30–33 GHz) standards, this letter presents a compact wideband widebeam ±45° dual-polarized dipole element antenna to form a wideband phased array antenna (PAA) covering the entire 24–33 GHz (∼31.6%) band. First, by placing two orthogonal coupling feeding baluns over a dual-polarized dipole to excite the dipole's two pairs of orthogonal arms and employing four parasitic patches, a ±45° dual-polarized dipole element antenna is developed, showing a compact size (0.34λ
₀
× 0.34λ
₀
at 24 GHz), wide −14 dB impedance bandwidth (24–33 GHz, 31.6%), wide 3 dB beamwidth (>100°), high polarization isolation (>25 dB), and high cross polarization discrimination (XPD) (>25 dB) within the −14 dB impedance bandwidth. Then, based on the element antenna, a 4 × 4-element ±45° dual-polarized PAA is designed, fabricated using the low temperature co-fired ceramic (LTCC) process, and measured. The measurements show that, within the entire 24–33 GHz band, the broadside scanning gain of the PAA is up to 14 dBi, and the 3 dB gain variation scanning range is >±41° with a peak up to ±60°.