SICL-Fed Balanced Antipodal Dipole Antenna With Wideband Operation and Cross-Polarization Improvement at Millimeter-Wave Band

A substrate integrated coaxial line-fed balanced antipodal dipole antenna array is proposed for millimeter-wave (MMW) applications in this letter. Different from the traditional dual-armed dipole antenna, a balanced antipodal dipole element with three arms is proposed to improve the cross-polarization level by canceling the vertically polarized electric-field components. A cross-polarization level of less than -20 dB is achieved over the entire frequency band. Meanwhile, a gap is etched on each dipole arm to achieve dual-mode operation and broaden the impedance bandwidth of the dipole element, and an impedance bandwidth of more than 65% is obtained. By combining the proposed dipole elements with the unequal feeding network, a 1 x 8 dipole antenna array is designed, fabricated, and measured. The measured results show that the proposed dipole antenna array can achieve a wide -10 dB impedance bandwidth of more than 54% from 24.5 to 43 GHz, a sidelobe level of low than -18 dB in E-plane, and a cross-polarization level of low than -20 dB. With the merits of wide operating bandwidth, low cross-polarization level, low sidelobe level, low profile, and easy integration, the proposed antenna array is valuable to advanced MMW communication systems.