  In this letter, a dual port antenna with polarization adjustability is
proposed. The loading effect of four ring slots stimulates a hybrid mode in the
antenna that generates eight magnetic monopoles with high gain in boresight.
Due to symmetrical configuration, adding a 90 degree-rotated port provides a
dual polarized antenna. Through controlling the phase difference between the
two ports, six types of polarization can be demonstrated. A prototype is
fabricated and measured in 28 GHz. Antenna shows a maximum gain of 13 dBi, X%
bandwidth and a good cross-polarization level in all polarization states.
Distinct features including low-profile, low-cost, single-layered and no
feeding network makes the antenna a suitable candidate for upcoming
millimeter-wave applications.
