Abstract A compact dual-band dual-mode and dual-polarized (DBDMDP) antenna based on an asymmetrical Y-shaped microstrip line feeding along with a square ring radiator is proposed. The structure is loaded with two pairs of L-strips to extend the lower mode bandwidth (center frequency fc = 9.36 GHz). This section is employed to change an electromagnetic field distribution and achieve dipole-like omni-directional linearly polarized (LP) radiation. The asymmetrical Y-shaped microstrip line feeding section is used to realize patch-like directional circular polarization (CP) radiation for the higher mode (at fc = 12.13 GHz). The measured results show that the 10-dB impedance bandwidths for the dipole mode and patch mode are equal to 730 MHz (7.72%, fc = 9.45 GHz) and 1648 MHz (14.26%, fc = 11.56 GHz), respectively, among which the 3 dB simulated axial ratio bandwidth of the patch mode is of 1280 MHz (10.74%, centre frequency of CP band fCP = 11.92 GHz). The two modes’ maximum gains at fc = 9.36 and 12.13 GHz are equal to 1.44 and 2.62 dBi, respectively. The maximum peak gain is of 3.32 dBi at frequency of 12.27 GHz. This single-feed patch antenna can be useful in wireless communication applications for its compact structure, considerable bandwidth, stable radiation pattern and polarization diversity.
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