Dual-Polarized Microstrip Antenna With Single-Dimension-Constraint Resonant Frequency

This article proposes an asymmetric dual-polarized microstrip antenna (DPMA) with single-dimension-constraint resonant frequencies for orthogonal polarizations. Different from regular DPMAs, the orthogonal modes of the proposed antenna are only determined by a single dimension, breaking the symmetry limitations of dual-polarized (DP) antennas and leading to the irrelevant dimension for optimized radiation properties of gain and beamwidth. The proposed antenna consists of a vertical-slot-etched rectangular patch with two groups of shorting vias and a horizontal slot on the ground. By feeding two ports with differential or common modes, the antiphase TM10 or antiphase epsilon-near-zero (ENZ) modes are excited for orthogonal polarizations in extremely asymmetric structures. As an application example for mobile terminals, a circular-polarized (CP) antenna with a 90°-phase-step two-way power divider is constructed and integrated onto the upper metal bezel with a high aspect ratio for satellite communications. The measured results show an overlapped bandwidth of 40 MHz and beamwidth beyond 80° in a volume of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.39\times 0.026\times 0.0065~\lambda _{0}^{3}$ </tex-math></inline-formula>, exhibiting the unique design approach for DP or CP antennas in extremely asymmetric platforms.