A Novel Design of Single-Layer Wideband Differential-Fed Dual-Polarized Patch Antenna Loaded With Mushroom Structures

This letter presents a novel design of a single-layer differential-fed dual-polarized antenna with low-profile, wideband, and high-isolation characteristics. The antenna is composed of a main cross-shape patch connected to four symbiotic patches by stepped stubs. The patches are symmetrically loaded with mushroom structures to generate extra resonant modes, characterized as TM $_{30}$ , TM $_{12}$ , TM $_{50}$ , and slot modes, which are combined with the TM $_{10}$ mode of the main patch for the wide bandwidth. Thanks to the differential feed and structural symmetry, a very high isolation is achieved among the ports. The final design with low profile of $0.08\lambda _{L}$ ( $\lambda _{L}$ is the free-space wavelength at the lowest operational frequency) has been fabricated and measured. The measurements result in a bandwidth of 51.9% [(6.0 to 10.2) GHz] for 10 dB return loss and an isolation of $\ge$ 42 dB. The dual-polarized broadside radiation is validated by far-field measurements showing an average gain of 8.6 dBi and a cross-polarization level of $\leq -\text{20}$ dB within the bandwidth.