Automatic Dependent Surveillance-Broadcast (ADS-B) technology is designed to supplement ground based radar in the air traffic control (ATC) system of tomorrow. ADS-B allows an aircraft to find its position, speed, and heading via a satellite navigation constellation and report this, as well as other flight-related information, to ground-based receivers and other aircraft within its transmission range. The satellites of the Iridium NEXT constellation, which is due to become operational in 2017, will each host an ADS-B receiver operated by Aireon LLC, making global near real-time tracking of aircraft possible for the first time. By using a micro-space design approach, similar performance and global coverage could be achieved by using a constellation of small satellites. The small satellite constellation approach could allow more countries to operate independent ATC systems, reduce operational costs, quicken deployment of new satellites, and make a global dataset of aircraft movements more readily accessible to a greater number of end users.
In the interest of developing technology that could be used in such a constellation, the University of Toronto Institute for Aerospace Studies Space Flight Laboratory (UTIAS-SFL) has developed an ADS-B receiver to be flown as a secondary payload on the upcoming CanX-7 mission. The spacecraft will use a 30×10×10 cm nanosatellite to demonstrate an ADS-B receiver and a drag sail deorbit device in low-Earth orbit. For the ADS-B payload, a commercial-off-the-shelf (COTS) ADS-B receiver was chosen in order to minimize development costs and reduce risk. Link simulation was performed in order to verify that the capabilities of the receiver were sufficient for space operations, and to derive requirements for the antenna. Based on these requirements, a circularly polarized patch antenna was designed and manufactured. The measured performance parameters of the various system components were then used to simulate the expected ADS-B coverage from low-Earth orbit.
