Abstract: Disclosed is a micropatch antenna comprising a radiating element and a ground plane separated by an air gap. Small size, light weight, wide bandwidth, and wide directional pattern are achieved without the introduction of a high-permittivity dielectric substrate. Capacitive elements are configured along the perimeter of at least one of the radiating element and ground plane. Capacitive elements may comprise extended continuous structures or a series of localized structures. The geometry of the radiating element, ground plane, and capacitive elements may be varied to suit specific applications, such as linearly-polarized or circularly-polarized electromagnetic radiation.

Abstract: Disclosed is a circularly-polarized antenna comprising a flat conducting ground plane, a radiator, and an excitation system disposed between the radiator and the ground plane. The radiator comprises a plurality of conducting segments separated from each other by a first dielectric medium and separated from the ground plane by a second dielectric medium. The plurality of conducting segments are symmetrically disposed about an antenna axis of symmetry orthogonal to the ground plane. The excitation system comprises a flat conducting exciter patch and four excitation sources with phase differences of 0, 90, 180, and 270 degrees. The excitation sources are generated on two orthogonal printed circuit boards.

Abstract: Disclosed is a micropatch antenna comprising a radiating element and a ground plane separated by an air gap. Small size, light weight, wide bandwidth, and wide directional pattern are achieved without the introduction of a high-permittivity dielectric substrate. Capacitive elements are configured along the perimeter of at least one of the radiating element and ground plane. Capacitive elements may comprise extended continuous structures or a series of localized structures. The geometry of the radiating element, ground plane, and capacitive elements may be varied to suit specific applications, such as linearly-polarized or circularly-polarized electromagnetic radiation.

Abstract: Disclosed is a micropatch antenna comprising a radiating element and a ground plane separated by an air gap. Small size, light weight, wide bandwidth, and wide directional pattern are achieved without the introduction of a high-permittivity dielectric substrate. Capacitive elements are configured along the perimeter of at least one of the radiating element and ground plane. Capacitive elements may comprise extended continuous structures or a series of localized structures. The geometry of the radiating element, ground plane, and capacitive elements may be varied to suit specific applications, such as linearly-polarized or circularly-polarized electromagnetic radiation.

Abstract: A ground plane for reducing multipath reception comprises a convex conducting surface and an array of conducting elements disposed on at least a portion of the convex conducting surface. Embodiments of the convex conducting surface include a portion of a sphere and a sphere. Each conducting element comprises an elongated body structure having a transverse dimension and a length, wherein the transverse dimension is substantially less than the length. The cross-section of the elongated body structure can have various user-specified shapes. Each conducting element can further comprise a tip structure. The azimuth spacings, lengths, and surface densities of the conducting elements can be functions of meridian angle. An antenna can be mounted directly on the conducting convex surface or on a conducting or dielectric support structure mounted on the conducting convex surface. System components, such as a navigation receiver, can be mounted inside the conducting convex surface.

Abstract: A navigation receiver processes signals transmitted by global navigation satellites and received by a set of antenna units. Each antenna unit is connected to a separate input port of an antenna multiplexer switch. Satellite signals received from each antenna unit are consecutively switched to the input of a common radiofrequency processing module. A common signal correlator generates a common in-phase correlation signal from the satellite signals received from all the antenna units. The common in-phase correlation signal is processed by a data processing module to demodulate information symbols from the received satellite signals. The common in-phase correlation signal is also processed by phase-lock loops and delay-lock loops to generate carrier phases and code delays from the received satellite signals. Embodiments are described in which, along with the common in-phase correlation signal, common functional blocks or hardware are used to process the satellite signals received from all the antenna units.

Abstract: The energy potential of a receiver receiving signals from a navigation satellite is calculated according to an algorithm which is a function of an estimate of the mean and an estimate of the variance of a correlation signal. Improving the accuracy of measuring the energy potential may be achieved by improving the variance estimate. The variance estimate may be determined from measurements of the correlation signal over long time intervals during operation of the receiver. The variance estimate may also be determined during a calibration procedure, or by mathematical modeling of the receiver.

Abstract: Base data received at a rover receiver is extrapolated to a rover measurement time referenced to a clock in the rover receiver. The base data comprises a plurality of base parameters, such as pseudo-ranges and full phases, calculated at base epochs from data received from navigation satellites. Base data is decomposed into a computed component, a common component, and an information component. Only the information component is extrapolated, thereby increasing the extrapolation time interval (during which base data are missing) over which an acceptable accuracy in determination of rover coordinates may be provided. The extrapolated base data is calculated by adding the computed component updated to the rover measurement time, the information component extrapolated to the rover measurement time, and the common component. A second-order recursive digital filter is used to generate the extrapolation function.

Abstract: An ordered set of physical points, each comprising a nominal point and an associated allowable deviation, is approximated by a sequence of geometric elements determined by a method of intersecting polytopes in a parametric space. A first bundle of geometric elements connecting a first subgroup of physical points is generated and mapped to a first polytope. A second bundle of geometric elements connecting a second subgroup of physical points is generated and mapped to a second polytope. If the intersection between the first polytope and the second polytope is not null, the points in the intersection region correspond to geometric elements which approximate the physical points in the combined two subgroups. The process is repeated iteratively for additional subgroups. The center point of the final intersection region corresponds to an approximate best-fit geometric element.

Abstract: A micropatch antenna system with simultaneous high bandwidth and low sensitivity to multipath radiation is achieved by positioning a radiating element within a cavity in a ground plane. Bandwidth and sensitivity to multipath radiation may be varied by varying the height of the radiating element above the bottom of the cavity and above the top of the ground plane. The electromagnetic and physical characteristics of the antenna system may be further controlled by introducing dielectric solids or wave-slowing structures between the bottom of the cavity and the radiating element. A dual-band micropatch antenna system with simultaneous high bandwidth and low sensitivity to multipath radiation may be similarly configured by stacking a second radiating element on top of the first radiating element.

Abstract: A navigation receiver processes signals transmitted by global navigation satellites and received by a set of antenna units. Each antenna unit is connected to a separate input port of an antenna multiplexer switch. Satellite signals received from each antenna unit are consecutively switched to the input of a common radiofrequency processing module. A common signal correlator generates a common in-phase correlation signal from the satellite signals received from all the antenna units. The common in-phase correlation signal is processed by a data processing module to demodulate information symbols from the received satellite signals. The common in-phase correlation signal is also processed by phase-lock loops and delay-lock loops to generate carrier phases and code delays from the received satellite signals. Embodiments are described in which, along with the common in-phase correlation signal, common functional blocks or hardware are used to process the satellite signals received from all the antenna units.

Abstract: A ground plane for reducing multipath reception comprises a convex conducting surface and an array of conducting elements disposed on at least a portion of the convex conducting surface. Embodiments of the convex conducting surface include a portion of a sphere and a sphere. Each conducting element comprises an elongated body structure having a transverse dimension and a length, wherein the transverse dimension is substantially less than the length. The cross-section of the elongated body structure can have various user-specified shapes. Each conducting element can further comprise a tip structure. The azimuth spacings, lengths, and surface densities of the conducting elements can be functions of meridian angle. An antenna can be mounted directly on the conducting convex surface or on a conducting or dielectric support structure mounted on the conducting convex surface. System components, such as a navigation receiver, can be mounted inside the conducting convex surface.

Abstract: Disclosed is a system and method for processing signals received from different global navigation satellite systems. The receiver includes a number of universal digital channels. The universal digital channel can be used to receive and process different code signals of each of the three navigation satellite systems GPS, GLONASS, and GALILEO. The universal digital channels have the same structure. Each of them can be tuned to receive different signals. The core of the universal digital channel is a code generator and a universal strobe generator.

Abstract: Disclosed is a receiver that receives at least three satellite signals and determines the contribution of dispersive elements, nondispersive elements, and phase windup to a phase difference between each received satellite signal and a corresponding generated signal.

Abstract: Disclosed is a method for determining coordinates of a mobile rover. The method includes determining a vector of one-shot code coordinates of the mobile rover. The method also includes determining a vector of phase increments by determining full phase differences for each navigation satellite in a plurality of navigation satellites in view at a discrete time interval (called a time epoch) and at a previous time epoch in a plurality of time epochs. A vector of radial range increments is determined from the full phase differences. A vector of rover phase coordinate increments is also determined using the vector of radial range increments. The vector of one-shot code coordinates and the vector of rover phase coordinate increments are then filtered to determine, at each time epoch, smoothed code coordinates of the mobile rover. Measured phase increments are cleared up from abnormal measurements.

Abstract: A patch antenna having a plurality of structures, referred to herein as comb structures, is disclosed that results in an antenna having a reduced overall patch size and weight as well as a broader the angular response pattern of the antenna. In a first embodiment, comb structures are attached to one of the surface of the patch or the surface of the ground plane. In a second embodiment, the comb structures are attached to both the patch and the ground plane in a manner such that the structures interleave with each other. The structures may be pins or ribs that are electrically connected to the ground plane and/or the patch, or may be any other suitable configuration depending upon the polarization of the signal to be transmitted or received.

Abstract: Base data received at a rover receiver is extrapolated to a rover measurement time referenced to a clock in the rover receiver. The base data comprises a plurality of base parameters, such as pseudo-ranges and full phases, calculated at base epochs from data received from navigation satellites. Base data is decomposed into a computed component, a common component, and an information component. Only the information component is extrapolated, thereby increasing the extrapolation time interval (during which base data are missing) over which an acceptable accuracy in determination of rover coordinates may be provided. The extrapolated base data is calculated by adding the computed component updated to the rover measurement time, the information component extrapolated to the rover measurement time, and the common component. A second-order recursive digital filter is used to generate the extrapolation function.

Abstract: Disclosed is a circularly-polarized antenna comprising a flat conducting ground plane, a radiator, and an excitation system disposed between the radiator and the ground plane. The radiator comprises a plurality of conducting segments separated from each other by a first dielectric medium and separated from the ground plane by a second dielectric medium. The plurality of conducting segments are symmetrically disposed about an antenna axis of symmetry orthogonal to the ground plane. The excitation system comprises a flat conducting exciter patch and four excitation sources with phase differences of 0, 90, 180, and 270 degrees. The excitation sources are generated on two orthogonal printed circuit boards.

Abstract: A micropatch antenna system with simultaneous high bandwidth and low sensitivity to multipath radiation is achieved by positioning a radiating element within a cavity in a ground plane. Bandwidth and sensitivity to multipath radiation may be varied by varying the height of the radiating element above the bottom of the cavity and above the top of the ground plane. The electromagnetic and physical characteristics of the antenna system may be further controlled by introducing dielectric solids or wave-slowing structures between the bottom of the cavity and the radiating element. A dual-band micropatch antenna system with simultaneous high bandwidth and low sensitivity to multipath radiation may be similarly configured by stacking a second radiating element on top of the first radiating element.

Abstract: An ordered set of physical points, each comprising a nominal point and an associated allowable deviation, is approximated by a sequence of geometric elements determined by a method of intersecting polytopes in a parametric space. A first bundle of geometric elements connecting a first subgroup of physical points is generated and mapped to a first polytope. A second bundle of geometric elements connecting a second subgroup of physical points is generated and mapped to a second polytope. If the intersection between the first polytope and the second polytope is not null, the points in the intersection region correspond to geometric elements which approximate the physical points in the combined two subgroups. The process is repeated iteratively for additional subgroups. The center point of the final intersection region corresponds to an approximate best-fit geometric element.