A Planar Millimeter-Wave Antenna Array with a Pillbox-Distributed Network

This article introduces a new structure of radiating element for developing a wideband planar antenna array for millimeter-wave applications. The proposed radiating element consists of a slot-coupled magnetoelectric (ME) dipole and two microstrip patches, which produce the merits in bandwidth and gain enhancements for the antenna. The unique structure of the radiating element is an excellent candidate for building up an antenna array in millimeter-wave frequencies. To design the millimeter-wave antenna array with a low complexity in the power-distributed network, a stacked pillbox power divider is used to deliver equal-phase power distributions to all array elements. To provide sufficient bandwidth for the antenna array, an improved transition structured by a rectangular waveguide (WR) and a differential substrate-integrated waveguide (SIW) is adopted. To verify our proposed design, a prototype of the antenna array is examined and measured. The array obtains an impedance bandwidth of 30.7%, covering the frequency range from 53 to 72 GHz. Stable radiation patterns are found with the 3 dB gain bandwidth of 25.4% and the maximum gain of 25.1 dBi. This proposed antenna array can be employed to potential applications in millimeter-wave communication systems.