Abstract: A microstrip-fed cylindrical slot antenna is provided for allowing better communication between an object and a satellite. The microstrip-fed cylindrical slot antenna comprises a cylindrical base member; a first conductive coating disposed on the cylindrical base member; at least one slot disposed in the conductive coating, the slot having a helical configuration about the cylindrical base member; and a feed line corresponding to each of the slots, the feed line crossing each respective slot and extending beyond the slot by a distance D.

Abstract: A GPS frequency converter is provided, according to the present invention, to down-convert the frequency of an incoming GPS signal. The converter includes first and second mixers, the former of which receives the incoming RF signal and a signal from a local oscillator. The local oscillator signal is increased by a factor of 98 and then subtracted from the incoming RF signal to produce a first intermediate frequency signal (IF). The first IF signal is then passed to the second mixer which subtracts the frequency of the local oscillator therefrom to produce a second intermediate frequency signal (IF). The second IF signal is passed through a limiter and output as the frequency converted signal.

Abstract: A navigation unit (10) for receiving navigation signals from a source thereof such as global positioning satellites is configured to rack mount and connect with a remote fixed antenna and for detached, self-powered operation using a directly mounted helical antenna (14). The preferred antenna (14) includes antenna elements composed of a thin film of conductive material (50) printed on a flexible dielectric substrate (44) rolled into a tubular configuration.