Broadband Endfire Magnetoelectric Dipole Antenna Array Using SICL Feeding Network for 5G Millimeter-Wave Applications

A broadband endfire antenna array is investigated for 5G millimeter-wave applications. First, an improved magnetoelectric (ME) dipole with a defected ground structure is proposed, which is excited by a planar L-probe. This proposed ME-dipole antenna shows stable radiation during the relative bandwidth of 53.0%. Next, a 16-way substrateintegrated coaxial line (SICL) feeding network is presented. Its bandwidth is 109.5% for |S11| ≤ -15 dB and insertion loss is less than 13.4 dB. This full-corporate SICL feeding scheme is utilized to construct the broadband antenna array. Finally, the proposed antenna array is fabricated and its performance is evaluated. Considering the impedance bandwidth for |S11| ≤ -10 dB, the 3 dB gain bandwidth, and the radiation efficiency, the overall measured operating bandwidth is 50.7%, which covers two main candidate frequency bands of 28 and 39 GHz. The cross-polarization level is less than -19.0 dB and the front-to-back ratio is better than 20.0 dB in the whole operating bandwidth. Additionally, a 4 × 4 2-D multibeam array is also simulated to verify the beamforming potential of the proposed antenna array.