An antenna element comprising: a housing having a base and a conducting plate, the housing having a cavity formed between the base and the conducting plate, the cavity being coupled to the conducting plate at an upper edge of the housing, the conducting plate having a radiating slot with a length and a width that extends longitudinally along a first axis and a second axis, respectively, the radiating slot having a first and a second edge along the first axis; and a feeding element having a feeding point, a feeding line and a stub, the feeding element is located in the cavity at a first predetermined distance between the base and the conducting plate for enabling dual resonant frequency impedance matching, the feeding line extending along the second axis of the conducting plate across the width of the radiating slot such that a first end of the feeding line is coupled with the feeding point on one side of the radiating slot, adjacent the first edge of the radiating slot and a second end of the feeding line extends past the second edge of the radiating slot, and the stub extending laterally from the feeding line; wherein the feeding element is an active feeding element (110, 910, 930) and the feeding line is an active feeding line and is to be coupled with a signal source through the feeding point, characterised in that the antenna element further comprises: a passive feeding element (920, 940), un-coupled from a signal source, including a passive feeding line located at an opposite end of the radiating slot away from the active feeding element (110, 910, 930), the passive feeding line extending across the radiating slot such that a first end of the passive feeding line with the passive feeding element (920, 940) extends past the second edge of the radiating slot and a second end of the passive feeding line extends past the first edge of the radiating slot; and wherein the passive feeding element (920, 940) further includes a passive stub extending laterally from the passive feeding line. a housing having a base and a conducting plate, the housing having a cavity formed between the base and the conducting plate, the cavity being coupled to the conducting plate at an upper edge of the housing, the conducting plate having a radiating slot with a length and a width that extends longitudinally along a first axis and a second axis, respectively, the radiating slot having a first and a second edge along the first axis; and a feeding element having a feeding point, a feeding line and a stub, the feeding element is located in the cavity at a first predetermined distance between the base and the conducting plate for enabling dual resonant frequency impedance matching, the feeding line extending along the second axis of the conducting plate across the width of the radiating slot such that a first end of the feeding line is coupled with the feeding point on one side of the radiating slot, adjacent the first edge of the radiating slot and a second end of the feeding line extends past the second edge of the radiating slot, and the stub extending laterally from the feeding line; wherein the feeding element is an active feeding element (110, 910, 930) and the feeding line is an active feeding line and is to be coupled with a signal source through the feeding point, characterised in that the antenna element further comprises: a passive feeding element (920, 940), un-coupled from a signal source, including a passive feeding line located at an opposite end of the radiating slot away from the active feeding element (110, 910, 930), the passive feeding line extending across the radiating slot such that a first end of the passive feeding line with the passive feeding element (920, 940) extends past the second edge of the radiating slot and a second end of the passive feeding line extends past the first edge of the radiating slot; and wherein the passive feeding element (920, 940) further includes a passive stub extending laterally from the passive feeding line. a passive feeding element (920, 940), un-coupled from a signal source, including a passive feeding line located at an opposite end of the radiating slot away from the active feeding element (110, 910, 930), the passive feeding line extending across the radiating slot such that a first end of the passive feeding line with the passive feeding element (920, 940) extends past the second edge of the radiating slot and a second end of the passive feeding line extends past the first edge of the radiating slot; and wherein the passive feeding element (920, 940) further includes a passive stub extending laterally from the passive feeding line.