Wideband Wide-Angle Scanning Endfire Phased Array Antenna Based on Heterogeneous Beam Elements for Millimeter-Wave Mobile Terminals

This article presents a new design of an endfire phased array antenna (PAA) using heterogeneous beam elements (HBEs) for wide-angle scanning. The HBEs are specially designed elements with inclined and controllable beam directions, which incorporate a printed dipole and a rotary ground to achieve the desired beam inclination. Then, the PAAs are constructed based on the proposed HBE, and the array arrangement is realized by adjusting the beam-inclined angle of each element. As a result, the proposed HBE PAAs effectively maintain a stable effective aperture across various scanning angles and thus achieve a wide scanning range with a low gain variation. Prototypes of
$1\times4$
and
$1\times8$
-element HBE PAAs are designed, fabricated, and measured. The simulated and measured results reveal a significant improvement within the scanning range for the proposed HBE PAAs compared to their standard counterparts. The
$1\times4$
and
$1\times8$
-element HBE PAAs achieve impressive scanning ranges of
$\ge \pm 70^{\circ }$
and
$\ge \pm 80^{\circ }$
, respectively, within a wide impedance bandwidth of 24.25–29.5 GHz (19.8%), at the cost of a slight decline in normal-direction gain (< 1.2 dBi). This design offers a promising solution to enhance the performance of PAAs for mmWave mobile terminals.