Multipath limiting antenna design considerations for ground based pseudolite ranging sources
The next generation of advanced aircraft landing system will utilize the Global Positioning System (GPS). The availabilityof GPS is augmented by the use of pseudolites "pseudo satellites." Pseudolites transmit a GPS-like signal that can be used as a ranging source in place of or in addition to ranging sources from a satellite. The Local Area Augmentation System (LAAS) is being used to further augment GPS for precision approaches and landings by using a concept known as Differential GPS (DGPS). One major error source in DGPS is due to transmitted signal reflections (multipath) off nearby obstacles. Efficient antenna design can be used to mitigate multipath by severely attenuating signals from negative elevation angles. The research contained in this document was conducted in order to optimize the current wideband airport pseudolite (WBAPL) multipath limiting antenna (MLA) for pseudolite transmission in the LAAS. To that end, three phases of study were conducted. The first stage modeled the ground-to-air link between the WBAPL transmitting MLA and the reception antenna during approaches with an attempt to define optimal WBAPL antenna locations. The second stage was conducted to characterize the basic pattern requirements of the WBAPL transmitting MLA and sought to project a hypothetical coverage volume given a preliminary pseudolite antenna pattern. The third stage was performed to attain some level of validation for the new WBAPL MLA transmitting antenna pattern measured by an external contractor through the independent synthesis of a similar antenna radiation pattern.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:aircraft landing system global positioning multipath limiting antenna pseudolite local area augmentation differential gps
Date of Publication:01/01/2001