Microstrip Antennas for Robust Navigation Receivers

For precise satellite navigation, the reception of more than one frequency band of the whole GPS/Galileo spectrum is required. However, interference from different sources like hand-sets, base-stations for mobile communications or military and civil aircraft radars is a permanent threat for the receiver. Consequently, large errors in positioning can arise. This is a serious problem and not acceptable in safety-of-life applications like aircraft landing. To minimize the impact of interferers, suitable steep bandpass filters or multiplexers with low insertion loss can be employed in the front end between the antenna and the LNA. A better way, however, is to avoid the additional expenditure and realize bandpass and stopband functions in the antenna design, which also reduces the noise figure of the whole receiver. This paper presents different broadband and narrowband antenna developments for multifrequency navigation receivers and a new concept to integrate a diplexer function directly in the antenna