Review of helices for DTV broadcast from HAPS prototype

A number of telecommunications experiments were flown on an autonomous, 68 metre non-rigid airship in November 2004. Although the digital television broadcast experiment was successful, it was found that the signal was occasionally entirely lost when the airship passed directly over one receiving station. The performance of the transmit helicial antenna is examined on a simple model of the airship gondola using a commercially available MOM software in attempt to identify features of the antenna that may have adversely affected the radiation pattern during the broadcast experiments. Two other types of helical antenna were also studied, and were found to potentially offer advantages in maintaining radiation pattern shape when installed on the gondola.