A Cross-Polarization Suppressed Probe-Fed Patch Antenna and Its Applications to Wide-Angle Beam-Scanning Arrays

In this article, H-plane cross-polarization (X-pol) radiation of probe-fed air-filled patch antennas is substantially suppressed by introducing two or more floating metal cylinders underneath the patch, respectively. The X-pol is canceled by the radiation of induced currents on metal cylinders. The working principle of the new X-pol suppressed patch (XSP) antenna is revealed by an approximate model. The X-pol level of a typical XSP antenna can be suppressed to lower than −49 and −37 dB theoretically and experimentally for
$| \theta |\le 60^{\circ }$
. Two
$1\times $
8-element arrays constructed by XSP antennas and conventional patch antennas are prototyped and measured at scanning beam angles of
$\theta = 0^{\circ }$
, −40°, and −65°. The measured co-polarization (co-pol) gain of the XSP antenna array is 0.7 and 0.9 dB larger than that of the conventional patch array at
$\theta = -40^{\circ }$
and −65°, respectively. Besides, the beam scanning angle with −30 dB X-pol level of the XSP antenna array can be as wide as
$| \theta |\le 40^{\circ }$
, while that of the conventional patch array is about
$| \theta |\le 12^{\circ }$
. A wide-band dual-polarized XSP antenna is also presented. The measured maximum H-plane X-pol level can be lower than −29 dB within 8.7% fractional bandwidth.