An antenna system, characterized by: a first antenna unit, comprising a first antenna element (AE1_1) and a second antenna element (AE1_2), wherein the first antenna element (AE1_1) and the second antenna element (AE1_2) are disposed on a first plane to receive and transmit a first frequency band signal and a second frequency band signal respectively, and wherein the first antenna element (AE1_1) and the second antenna element (AE1_2) are not directly connected; and a second antenna unit, comprising a third antenna element (AE2_1) and a fourth antenna element (AE2_2), wherein the third antenna element (AE2_1) and the fourth antenna element (AE2_2) are disposed on a second plane to receive and transmit a third frequency band signal and a fourth frequency band signal respectively, and wherein the third antenna element (AE2_1) and the fourth antenna element (AE2_2) are not directly connected; wherein the first plane is substantially perpendicular to the second plane, wherein the first frequency band signal and the third frequency band signal are within a first frequency band, wherein the second frequency band signal and the fourth frequency band signal are within a second frequency band, wherein the first frequency band is different from the second frequency band, and wherein the first antenna element (AE1_1) has a first polarization direction and the second antenna element (AE1_2) has a second polarization direction which are orthogonal to each other, and the third antenna element (AE2_1) has a third polarization direction and the fourth antenna element (AE2_2) has a fourth polarization direction which are orthogonal to each other. a first antenna unit, comprising a first antenna element (AE1_1) and a second antenna element (AE1_2), wherein the first antenna element (AE1_1) and the second antenna element (AE1_2) are disposed on a first plane to receive and transmit a first frequency band signal and a second frequency band signal respectively, and wherein the first antenna element (AE1_1) and the second antenna element (AE1_2) are not directly connected; and a second antenna unit, comprising a third antenna element (AE2_1) and a fourth antenna element (AE2_2), wherein the third antenna element (AE2_1) and the fourth antenna element (AE2_2) are disposed on a second plane to receive and transmit a third frequency band signal and a fourth frequency band signal respectively, and wherein the third antenna element (AE2_1) and the fourth antenna element (AE2_2) are not directly connected; wherein the first plane is substantially perpendicular to the second plane, wherein the first frequency band signal and the third frequency band signal are within a first frequency band, wherein the second frequency band signal and the fourth frequency band signal are within a second frequency band, wherein the first frequency band is different from the second frequency band, and wherein the first antenna element (AE1_1) has a first polarization direction and the second antenna element (AE1_2) has a second polarization direction which are orthogonal to each other, and the third antenna element (AE2_1) has a third polarization direction and the fourth antenna element (AE2_2) has a fourth polarization direction which are orthogonal to each other.