In this paper, a patch antenna with a unique shape and feeding at terahertz frequency is presented. The shape of the patch can change between three shapes of triangle, rectangle, circle and slotted patches by using the properties of graphene. In this way, by changing the shape of the patch, it is possible to simultaneously take advantage of the features of patches with different shapes in one antenna structure. In addition to the ability of changing the resonance frequency of the antenna in the range of 3.8 to 5.3 THz, the polarization is also changeable between linear and circular polarization, so, we have a frequency and polarization reconfigurable antenna. Besides, by using a metasurface and proximity coupled feed, the gain of the antenna has been improved and the maximum gain of 3.7 dBi has been achieved. The provided antenna having a suitable impedance bandwidth in all states, and the maximum bandwidth 28.5%, can be used for wideband applications.
