Methods and apparatus are disclosed for passively steering an antenna disposed on a balloon in a balloon network. An example balloon involves: (a) an antenna and (b) a pressure-sensitive mechanism in mechanical communication with the antenna such that a change in the balloon's altitude causes at least an element of the antenna to rotate upward or downward, a separation distance between two or more radiating elements to increase or decrease, or a separation distance between the two or more radiating elements and a reflector to increase or decrease.