An apparatus comprising: an array of tapered slot antenna elements, the array having a horizontal polarization slot antenna portion oriented in a first plane and a vertical polarization slot antenna portion oriented in a second plane perpendicular to the first plane; each slot antenna portion of each antenna element having a first tapered slot formed by a gap in a metallization layer positioned on a first side of a dielectric substrate, and an associated first feedline port formed from a first metallization stripline positioned on a second side of the dielectric substrate, the first metallization stripline crossing over the first gap in the metallization layer to couple electromagnetic radiation from the antenna element to free space within a first frequency band; at least a subset of the antenna elements having a second slot joined to the first slot and formed by a second gap in the metallization layer positioned on the first side of the dielectric substrate, and an associated second feedline port formed from a second metallization stripline positioned on the second side of the dielectric substrate, the second metallization stripline crossing over the second gap in the metallization layer to couple electromagnetic radiation from the antenna element to free space within a second frequency band, the second frequency band being lower than the first frequency band; and, a plurality of selectable impedance elements, each selectable impedance element connected to a respective antenna element positioned between elements of the at least a subset of the antenna elements, the selectable impedance elements configured to switch to one of a high impedance, low impedance, or intermediate impedance when the second frequency band is in use. an array of tapered slot antenna elements, the array having a horizontal polarization slot antenna portion oriented in a first plane and a vertical polarization slot antenna portion oriented in a second plane perpendicular to the first plane; each slot antenna portion of each antenna element having a first tapered slot formed by a gap in a metallization layer positioned on a first side of a dielectric substrate, and an associated first feedline port formed from a first metallization stripline positioned on a second side of the dielectric substrate, the first metallization stripline crossing over the first gap in the metallization layer to couple electromagnetic radiation from the antenna element to free space within a first frequency band; at least a subset of the antenna elements having a second slot joined to the first slot and formed by a second gap in the metallization layer positioned on the first side of the dielectric substrate, and an associated second feedline port formed from a second metallization stripline positioned on the second side of the dielectric substrate, the second metallization stripline crossing over the second gap in the metallization layer to couple electromagnetic radiation from the antenna element to free space within a second frequency band, the second frequency band being lower than the first frequency band; and, a plurality of selectable impedance elements, each selectable impedance element connected to a respective antenna element positioned between elements of the at least a subset of the antenna elements, the selectable impedance elements configured to switch to one of a high impedance, low impedance, or intermediate impedance when the second frequency band is in use.