Abstract: The present invention relates to an antenna design, which is usable in accurate position determinations. The antenna comprises a cylinder-shaped housing, a ground plane, and a single choke ring, where the choke ring and the housing are part of the same entity. A single round-shaped patch element is connected by four legs onto a circuit board, so that a rotationally symmetric structure is achieved. The height of the patch element is less than the height of the choke ring. Differential feeding network is placed on the bottom surface of the circuit board, where the ground plane forms the top surface of the circuit board. Two circular polarizations are enabled simultaneously. A self-calibration loop is also made possible.

Abstract: The present invention relates to an antenna design, which is usable in accurate position determinations. The antenna comprises a cylinder-shaped housing, a ground plane, and a single choke ring, where the choke ring and the housing are part of the same entity. A single round-shaped patch element is connected by four legs onto a circuit board, so that a rotationally symmetric structure is achieved. The height of the patch element is less than the height of the choke ring. Differential feeding network is placed on the bottom surface of the circuit board, where the ground plane forms the top surface of the circuit board. Two circular polarizations are enabled simultaneously. A self-calibration loop is also made possible.

Abstract: A method for evaluating a distance between at least a first antenna unit and a second antenna unit by two-way transmission of at least two signals having different circular polarizations between the antenna units. Phase information is determined and used to determine at least a first phase sum and a second phase sum, where the phase sums are further utilized in determination of at least one distance indicator that is indicative of the distance between the first antenna unit and the second antenna unit.

Abstract: A method for determining at least one distance between pairs of antennas, the method including performing self-measurements and first two-way transmissions at first time intervals, first one-way transmissions at second time intervals, second two-way transmissions at third time intervals, and second one-way transmissions at fourth time intervals. The method also includes determining phase information based on the performed transmissions and determining distance information regarding the at least one distance.

Abstract: A method for performing radio transmissions, including assigning radio units to one subgroup of first radio units, assigning radio units to one subgroup of second radio units, assigning a signal frequency set to each subgroup of first radio units, assigning a signal frequency subset in a signal frequency set of a subgroup of first radio units to each second radio unit in a subgroup of second radio units associated with the subgroup of first radio units, wherein signal frequency subsets assigned to each second radio unit in the same subgroup of second radio units differs from each other in at least one measurement frame, transmitting, via one of the first radio units, a signal of frequencies of the assigned signal frequency set, and transmitting, via one of the second radio units, a signal of frequencies of the assigned signal frequency subset.

Abstract: A method for evaluating a distance between at least a first antenna unit and a second antenna unit by two-way transmission of at least two signals having different circular polarizations between the antenna units. Phase information is determined and used to determine at least a first phase sum and a second phase sum, where the phase sums are further utilized in determination of at least one distance indicator that is indicative of the distance between the first antenna unit and the second antenna unit.

Abstract: A method for determining a clock offset between local clocks of at least one pair of radio units, includes performing two-way transmissions between at least one pair of radio units using signals including selected frequencies, determining phase information regarding the signals received at the radio units, determining phase differences based on the phase information, determining at least one clock offset variable, and determining an estimated maximum error in the determined clock offset variable based on maximum errors of the phase differences to determine if the maximum error of the determined clock offset variable allows the clock offset value to be unambiguously determined.