Millimeter-Wave 45°-Polarized LTCC Phased Array Using Wide-Beam Patch-Via-Wall Elements for Wide-Angle Scanning Applications

In this article, a millimeter-wave 45°-polarized low-temperature co-fired ceramics (LTCC) phased array using wide-beam patch-via-wall antenna elements is investigated for wide-angle scanning applications, which can cover n257/n258 bands (24.25–29.5 GHz). First, a novel ±45° wide-beam dual-polarized planar antenna element is proposed, which is constructed by loading one stacked patch and four patch-via-wall structures on a conventional patch antenna. Among them, the stacked patch is used for the realization of the wideband feature and the patch-via-wall loadings are beneficial for the wide-beam feature by generating vertical electrical fields. Second, the mechanism of the wide-beam feature is investigated by analyzing the electric field distributions of the patch antenna on E- and H-planes, respectively. By optimizing the patch-via-wall loadings, synthetic electric fields with wide-beam features on both horizontal and vertical directions can be realized. Accordingly, the beamwidth of the proposed ±45° dual-polarized antenna element can be enlarged from 98° to 128°. Further, the proposed wide-beam antenna element is applied to construct a
$4\times4$
array integrated in an LTCC package within a small distance of about
$0.45\lambda _{0}$
. Moreover, several decoupling loops are loaded between adjacent elements to introduce an extra path that can reduce the couplings below −21 dB. As a result, the array can achieve a good beam-scanning capability over a wideband of 19.7% with a maximum scanning angle up to ±58° and a small gain variation less than 2.8 dB. Meanwhile, over the entire bandwidth, the scanning angles are up to ±55°. In addition, the active S-parameters almost always remain below −10 dB, enabling good impedance matching when scanning at large angles. With these features, the proposed antenna array has the potential for wide-angle scanning applications.