A vehicle computer comprises a processor and a memory. The memory stores instructions executable by the processor to receive a location of a first stationary directional short-wave antenna, to determine a line from a vehicle location to the location of the first stationary antenna, to transmit a short-wave request message to the first stationary short-wave antenna based on the determined line, the message including vehicle data, and upon receiving a short-wave acknowledgment message from the first stationary short-wave antenna, to transmit a second short-wave message including vehicle data.