Indoor or Underground GNSS Repeater System Based on Directional Antennas

Saulius Rudys, Mantautas Rudys

The idea offers an exceedingly accurate indoor navigation system. Indoor systems based on GNSS repeaters conventionally consist of an omnidirectional receiving antenna, a signal amplifier, and an omnidirectional transmitting antenna. Systems currently in use return the same coordinates in opposite directions because the path to the repeater’s antenna is of the same length, regardless of direction. If the receiver is on the satellite(s) side from the repeater antenna, the receiver will return false coordinates. In order to provide more accurate navigation results, the unwanted signals need to be eliminated while ensuring that the navigation devices receive only those satellite signals that form as straight a path to the device as possible. To achieve this, it is necessary to use opposite-pointing directional antennas for both receiving and transmitting. In a configuration of this nature, directional antennas keep the satellite signal path virtually straight. This results in greater navigation accuracy. Higher directional antenna gain allows for wider coverage areas and requires fewer installation points, meaning system setup costs may be lower than those required for conventional repeaters.