Optimisation of the antenna placement for an airport surveillance system

We present an optimisation method for the placement of the antennas of a surveillance system on an airport which is based on multilateration. The system takes advantage of a signal sent by an aircraft (for example, SSR Mode S). The measurement error in such a multilateration system is influenced by the Dilution Of Precision (DOP) which reflects the geometry of the surveillance antennas in relation to the position of the aircraft. We derive the mathematical background for the DOP calculation where no timing information is available in the transmitted signal and introduce a gradient free optimisation method to optimise the locations at which to place the antennas. The cost function of the optimisation is based on the distribution of the DOP values in the regions where an aircraft is expected. Further propagation characteristics such as power delay profiles, directions of arrival and received power diagrams, help the engineer to fine tune the design of the system.