A Millimeter-Wave Compact Pattern Reconfigurable Antenna Array With Improved Spatial Coverage

A pattern reconfigurable antenna array is proposed for the purpose of improving spatial coverage at millimeter-wave frequencies. An endfire magnetoelectric (ME) dipole and two slot-patches with compact substrate-integrated geometries are employed as sub-radiators of the antenna. A method of adjusting impedance characteristics of the sub-radiators by using p-i-n diodes is investigated to obtain three reconfigurable radiation modes of the antenna that aim at endfire, forward broadside, and backward broadside directions, respectively. With the aid of the virtual shorting and polarization orthogonality characteristics of the antenna, additional RF chokes in the dc bias circuits are saved, which further simplifies the overall configuration. A Ka-band $1\times 8$ array composed of the antennas is then designed, fabricated, and tested, which confirms a bandwidth of 16.9%, a maximum gain of 15.8 dBi, and a significantly improved spatial coverage of 93% at 5 dBi or 85% at 8 dBi. Benefiting from the fully substrate-integrated geometry and satisfactory performance, the proposed antenna may find possible applications in advanced millimeter-wave mobile terminals.