A Design Method for a Dual-Band and Dual-Polarized Patch Antenna Based on a Single-Layer Dielectric Substrate for UAV Communication Applications

This letter proposes a design method for a single-layer dual-band dual-polarized patch antenna targeting the 2.4 GHz/5 GHz bands. First, dual-band broadside radiation is realized by exciting two resonant modes within a shared architecture. At the low band, the antenna operates in the first-order mode, with radiation mainly contributed by the outer square-ring patch. At the high band, the third-order mode is effectively excited, and radiation is mainly provided by the inner square patch. Dual polarization is realized through structural symmetry. Second, to accommodate dual-band scenarios with a relatively large frequency ratio, the mode-isolation technique is introduced. By loading choke stubs, the low- and high-band operating modes are effectively separated. Third, to improve impedance matching without increasing feeding complexity, the capacitive-loading technique is adopted. Specifically, appropriate slots are introduced to provide additional capacitance in the high band, thereby achieving good dual-band impedance matching. Finally, a prototype antenna is designed, fabricated, and measured. The measured results show good impedance matching in both bands with a frequency ratio of 2.35; the isolation between the two orthogonal polarization ports is better than 20.0 dB in the low band and 14.5 dB in the high band. In addition, a 1 × 4 antenna array is designed and measured, achieving interelement isolation better than 17.0 dB in the low band and 30.0 dB in the high band, further confirming the good scalability of the proposed design for array applications.