An axial fan (300, 400, 500), comprising: a hub configured to be driven by motor to rotate about a fan rotational axis; a band that surrounds the rotational axis and is concentric with the hub, the band including a cylindrical portion that extends in parallel to the fan rotational axis, a lip portion that extends in at an angle to the fan rotational axis, and a curved intermediate portion that connects one end of the cylindrical portion to one end of the lip portion; blades that protrude radially from the hub, each blade comprising a root that is connected to the hub and a tip that is connected to a hub-facing surface of the cylindrical portion; and a structurally-reinforcing rib that protrudes from the hub-facing surface of the cylindrical portion, the rib disposed between respective tips of an adjacent pair of the blades, wherein a circumferential dimension of the rib is at least 40 percent of a distance along the hub-facing surface between the respective tips of the blades of the adjacent pair of the blades, wherein the hub, the blades and the band are formed as a single piece; wherein the rib comprises a plurality of ribs, each rib being disposed between a pair of adjacent blades such that a single rib is disposed between the blades of a given pair of adjacent blades, wherein a distance between the fan rotational axis and the band is constant for every location along a line that extends about the circumferences of the band, where the line is disposed on the hub-facing surface of the band at the band trailing end, wherein the line does not intersect with the rib, characterized in that the rib extends onto the curved intermediate portion, and in that a radial dimension of the band is non-uniform along the line, wherein the radial dimension of the band has a maximum value at locations corresponding to a rib. a hub configured to be driven by motor to rotate about a fan rotational axis; a band that surrounds the rotational axis and is concentric with the hub, the band including a cylindrical portion that extends in parallel to the fan rotational axis, a lip portion that extends in at an angle to the fan rotational axis, and a curved intermediate portion that connects one end of the cylindrical portion to one end of the lip portion; blades that protrude radially from the hub, each blade comprising a root that is connected to the hub and a tip that is connected to a hub-facing surface of the cylindrical portion; and a structurally-reinforcing rib that protrudes from the hub-facing surface of the cylindrical portion, the rib disposed between respective tips of an adjacent pair of the blades, wherein a circumferential dimension of the rib is at least 40 percent of a distance along the hub-facing surface between the respective tips of the blades of the adjacent pair of the blades, wherein the hub, the blades and the band are formed as a single piece; wherein the rib comprises a plurality of ribs, each rib being disposed between a pair of adjacent blades such that a single rib is disposed between the blades of a given pair of adjacent blades, wherein a distance between the fan rotational axis and the band is constant for every location along a line that extends about the circumferences of the band, where the line is disposed on the hub-facing surface of the band at the band trailing end, wherein the line does not intersect with the rib, the rib extends onto the curved intermediate portion, and in that a radial dimension of the band is non-uniform along the line, wherein the radial dimension of the band has a maximum value at locations corresponding to a rib.