A communication system for an altitude changing object is provided. The communication system can include an antenna system having one or more antennas. The one or more antennas can be associated with a single fixed radiation pattern. The communication system can include one or more processors configured to execute a control routine to perform operations. The operations can include obtaining data indicative of one or more communication parameters associated with the altitude changing object. The operations can include determining a transmit power for each of the one or more antennas based at least in part on the one or more communication parameters. The operations can include controlling the antenna system based at least in part on the transmit power to communicate with a node in the communication network.