Abstract: A test installation for simulating multiple reflections of GNSS signals, the installation including a bottom screen that is reflective in the radio frequency spectrum; a top screen above the bottom screen, wherein the top screen is partly transparent in a radio frequency spectrum, and wherein the top screen is substantially dome-shaped and has a height of 1 to 3 meters; and a GNSS antenna between the top screen and the bottom screen; wherein the test installation is configured to measure the GNSS signals received by the antenna and to simulate the multipath reflections.

Abstract: A test installation for simulating multiple reflections of GNSS signals, the installation including a bottom screen that is reflective in the radio frequency spectrum; a top screen above the bottom screen, wherein the top screen is partly transparent in a radio frequency spectrum, and wherein the top screen is substantially dome-shaped and has a height of 1 to 3 meters; and a GNSS antenna between the top screen and the bottom screen; wherein the test installation is configured to measure the GNSS signals received by the antenna and to simulate the multipath reflections.

Abstract: A test installation for simulating multiple reflections of GNSS signals, the installation including a top screen that is semitransparent in a radio frequency portion of the electromagnetic spectrum, wherein the top screen is substantially dome-shaped; a bottom screen that is reflective in the radio frequency portion of the electromagnetic spectrum; the top semitransparent screen over the bottom reflecting screen; and a GNSS antenna connected to a receiver and located between the top screen and the bottom screen.

Abstract: A test installation for simulating multiple reflections of GNSS signals, the installation including a top screen that is semitransparent in a radio frequency portion of the electromagnetic spectrum, wherein the top screen is substantially dome-shaped; a bottom screen that is reflective in the radio frequency portion of the electromagnetic spectrum; the top semitransparent screen over the bottom reflecting screen; and a GNSS antenna connected to a receiver and located between the top screen and the bottom screen.

Abstract: A patch antenna includes a capacitive radiating patch, a ground plane, and vertical coupling elements electrically connected to defined portions of the capacitive radiating patch and the ground plane. The capacitive radiating patch includes an array of conductive segments along the periphery and within the interior of the capacitive radiating patch. Capacitors are electrically connected to specific conductive segments in a defined pattern. Vertical coupling elements electrically connect specific conductive segments along the periphery of the capacitive radiating patch to the ground plane. Vertical coupling elements can be conductors or defined combinations of resistors, inductors, and capacitors. Various embodiments of the patch antenna are configured for linear polarization and circular polarization. Relative to a conventional patch antenna of a similar size, a patch antenna with a capacitive radiating patch has a broader operational bandwidth and a broader radiation pattern in the forward hemisphere.

Abstract: An antenna system for a global navigation satellite system reference base station is disclosed. The antenna system includes an antenna positioned above a high capacitive impedance surface (HCIS) ground plane. Over a specific range of the lateral dimension of the HCIS ground plane and the height of the antenna above the HCIS ground plane, a high level of multipath suppression and high sensitivity for low-elevated satellites can be simultaneously maintained. The HCIS ground plane can be fabricated as a flat conducting plate with an array of conducting elements such as pins, pins with expanded tips, or mushroom structures. Alternatively, the HCIS can be fabricated as a flat conducting plate with a concentric series of choke rings. The antenna system can provide a positioning accuracy of +/?1 mm, an order of magnitude improvement over previous designs.

Abstract: A navigation receiver mounted on a moving vehicle receives navigation signals transmitted from global navigation satellites. The navigation signals are separated into direct navigation signals, navigation signals reflected from an object, and navigation signals reflected from an environmental surface. The signal separation is based on algorithms including various combinations of signal strength, change in signal strength, delay time, spectral width, change in spectral width, and user-defined thresholds. The navigation signals reflected from an environmental surface are eliminated from further processing. The position of the navigation receiver is calculated based on the direct navigation signals. The object is detected, and the position of the object is calculated, based on the navigation signals reflected from the object. If the object is determined to lie in the path of the moving vehicle, a command can be generated to avoid collision between the moving vehicle and the object.

Abstract: A navigation receiver mounted on a moving vehicle receives navigation signals transmitted from global navigation satellites. The navigation signals are separated into direct navigation signals, navigation signals reflected from an object, and navigation signals reflected from an environmental surface. The signal separation is based on algorithms including various combinations of signal strength, change in signal strength, delay time, spectral width, change in spectral width, and user-defined thresholds. The navigation signals reflected from an environmental surface are eliminated from further processing. The position of the navigation receiver is calculated based on the direct navigation signals. The object is detected, and the position of the object is calculated, based on the navigation signals reflected from the object. If the object is determined to lie in the path of the moving vehicle, a command can be generated to avoid collision between the moving vehicle and the object.

Abstract: A patch antenna includes a capacitive radiating patch, a ground plane, and vertical coupling elements electrically connected to defined portions of the capacitive radiating patch and the ground plane. The capacitive radiating patch includes an array of conductive segments along the periphery and within the interior of the capacitive radiating patch. Capacitors are electrically connected to specific conductive segments in a defined pattern. Vertical coupling elements electrically connect specific conductive segments along the periphery of the capacitive radiating patch to the ground plane. Vertical coupling elements can be conductors or defined combinations of resistors, inductors, and capacitors. Various embodiments of the patch antenna are configured for linear polarization and circular polarization. Relative to a conventional patch antenna of a similar size, a patch antenna with a capacitive radiating patch has a broader operational bandwidth and a broader radiation pattern in the forward hemisphere.

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: Choke-ring ground planes are commonly used for multipath rejection in geodetic surveying systems. Such ground planes consist of a thick metal disc with deep grooves on one of the flat surfaces. An antenna is mounted in the center of the grooved surface. Known ground planes used in dual frequency communication systems (L1 and L2) could not be constructed to have good rejection of multipath signals in both L1 and L2 frequencies; instead, they are constructed for good rejection of multipath signals in L2 but not good for the rejection of multipath signals in L1. A first invention provides for equally good multipath rejection for both L1 and L2 frequencies by incorporating novel electromagnetic filter structures within the choke-ring grooves. The filter structures of the present invention enable the choke ring to provide multipath rejection in each frequency band which is as good as, or better than, the multipath rejection achieved in the L2 band with existing devices.