A Low-Cost SISL Differentially Fed Dual-Polarized Stacked Patch Antenna With Enhanced Common-Mode Suppression Using Characteristic Mode Analysis

Abstract

A wideband differentially fed dual-polarized stacked patch antenna with high common-mode (CM) suppression is proposed in this article using the characteristic mode analysis (CMA) and the substrate integrated suspended line (SISL) technology. Based on the CMA, orthogonal slots are loaded within the stacked patch to enhance the directivity of the second-order degenerate modes and reallocate the resonating frequency of the fundamental degenerate modes. A crossed dipole is introduced within the driven patch to ensure polarization uniformity between the two paired degeneracies. The CM suppression level ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}_{\mathrm {CC}}11$ </tex-math></inline-formula> ) is enhanced from–10 to–1.30 dB within the frequency range of 4.0–7.0 GHz by embedding circular slots embedded within the stacked patch and controlling the slot radius. Measured results demonstrate a–10 dB differential impedance bandwidth of 28.4% (4.62–6.18 GHz) and high isolation of better than–39.5 dB between the differential ports. The antenna depicts stable measured radiation patterns with low cross-polarization (<–30 dB). The measured average antenna gain and efficiency are 9.55 dBi and 85.5% within the DM passband. In addition, a high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}_{\mathrm {CC}}11$ </tex-math></inline-formula> better than–1.05 dB is measured within the desired DM band.