A Miniaturized Dual-Band Dual-Beam Filtering Patch Antenna With Orthogonal Beam Pointing

A miniaturized dual-band dual-beam filtering patch antenna with orthogonal beam pointing is proposed. By using a cross-shaped feedline with two pairs of orthogonal common-mode (CM) currents, TM02 and TM20 modes are excited with suppression of adjacent TM10 and TM12 modes, and radiation null 1 (RN1) is introduced in both polarizations. Due to far-field nulls of orthogonal dual-beam patterns, intrinsic radiation null 1 (RN
$_{\mathrm {i}1}$
) and RN
$_{\mathrm {i}2}$
are generated. With miniaturization, by etching periodic short slots, RN
$_{\mathrm {i}3}$
related to the high-order harmonic can be used, its frequency can be significantly controlled, and the radiation pattern is reshaped to effectively improve the rejection at RN
$_{\mathrm {i}3}$
in
$x$
-polarization. To ensure high selectivity at each sideband while remaining compact, nested two quasi-circular loops (QCLs) and a cross-shaped metal strip (CSMS) are employed to create RN2–RN4 in both polarizations. Thus, a total of eleven RNs are yielded, aching high selectivity and deep stopband rejection. With a small size of
$0.40\lambda _{0} \times 0.44\lambda _{0} \times 0.028\lambda _{0}$
, a prototype is fabricated and tested. Measured results show that dual beams in 5.3–5.53 GHz point toward the
$x$
-axis direction, while dual beams in 6.34–6.66 GHz point toward the
$y$
-axis direction, satisfying the requirements of point-to-multipoint scenarios providing different wireless services in orthogonal orientations.