Abstract: A broadband tapered monopole antenna includes a counterpoise that is oriented horizontally and a planar radiator that is oriented vertically. The planar radiator is bounded by a curved edge extending between first and second vertices, a first edge adjacent to the curved edge, a second edge adjacent to the first edge, and a third edge adjacent to both the second edge and the curved edge. The first edge extends vertically between the second vertex and a third vertex. The second edge extends horizontally between the third vertex and a fourth vertex. The third edge extends vertically between the fourth vertex and the first vertex. A gap width between the curved edge and the planar counterpoise increases monotonically between a minimum gap width at the first vertex and a maximum gap width at the second vertex. The planar radiator has a maximum height that is greater than the maximum gap width.

Abstract: An antenna feed for a stackable antenna system includes a polarization converter that continuously surrounds an omnidirectional antenna. Electromagnetic radiation emitted by the omnidirectional antenna and having an initial polarization passes through the first polarization converter, which converts the initial polarization into a non-vertical linear polarization. A feedline located outside of the first polarization converter forms a helix that wraps around the first polarization converter such that it runs perpendicularly to the non-vertical linear polarization. When the width of the feedline is sufficiently small, electrons in metal of the feedline will not be excited by the radiation, and the radiation will transmit through the feedline with minimal impact on the omnidirectional antenna's gain profile. The feedline may be used to feed a second antenna located vertically above the omnidirectional antenna.