A direction-finding antenna includes at least a first set of radiating elements configured to radiate at least a first wavelength (λ.sub.1) and a second set of radiating elements configured to radiate at a second wavelength (λ.sub.2) that is shorter than the first wavelength (λ.sub.1). The first set of radiating elements defines a first circle having a first radius. The second set of radiating elements defines a second circle having a second radius that is smaller than the first radius of the first circle. The direction-finding antenna further includes a transmission line-based multiplexer configured to selectively couple the first set of radiating elements or the second set of radiating elements to a radio frequency (RF) feed line, or a plurality of switches configured to selectively couple selected radiating elements of the first set of radiating elements or the second set of radiating elements to the RF feed line.

A direction-finding antenna includes at least a first set of radiating elements configured to radiate at least a first wavelength (λ.sub.1) and a second set of radiating elements configured to radiate at a second wavelength (λ.sub.2) that is shorter than the first wavelength (λ.sub.1). The first set of radiating elements defines a first circle having a first radius. The second set of radiating elements defines a second circle having a second radius that is smaller than the first radius of the first circle. The direction-finding antenna further includes a transmission line-based multiplexer configured to selectively couple the first set of radiating elements or the second set of radiating elements to a radio frequency (RF) feed line, or a plurality of switches configured to selectively couple selected radiating elements of the first set of radiating elements or the second set of radiating elements to the RF feed line.

A device and method for improving the accuracy of angle of arrival and departure computations is disclosed. The device and method rely on manipulation of the antenna switching pattern to achieve an improved calculation of arrival angle. In one embodiment, the device calculates an estimate angle of arrival using conventional methods. The device then determines which of a plurality of different antenna switching pattern yields the more accurate results at this estimated angle of arrival. The AoA measurement is then repeated using the preferred antenna switching pattern. In another embodiment, the device captures the amplitude and/or phase of the signal from each antenna element. The device then sorts these antenna elements and defines a preferred antenna switching pattern based on the sort list. The AoA measurement is then performed using the preferred antenna switching pattern. In another embodiment, neural networks may be utilized to determine the preferred antenna switching pattern.

A radio presence-advertising signal (PAS) a PAS emitter is simultaneously received at two or more co-located directional antennas that are coupled to respective radio receivers. The antennas have reception sensitivity lobes that overlap to define a region of interest at the overlap. Substantially cotemporaneous signal strength indications are obtained from the radio receivers. A difference signal representative of a difference between two of the obtained signal strength indications of the respective antennas is generated. An average signal representative of a running average of two or more of the obtained signal strength indications is generated and used to produce a normalized confidence indicator indicating a level of confidence that the PAS emitter is disposed inside (e.g., centered in) the region of interest or alternatively indicating a level of confidence that the PAS emitter is disposed outside the region of interest. Action is taken or avoided based on the confidence signal.

A receiver system comprising: an input terminal configured to receive input signalling comprising a plurality of antenna-signals, wherein the plurality of antenna-signals each comprise information that corresponds to a first-frequency-bin and a second-frequency-bin. AoA-blocks can determine a first-angle-of-arrival and a second-angle-of-arrival associated with the first- and second-frequency-bins. A first-weighting-determination-block configured to, based on the first-angle-of-arrival and the second-angle-of-arrival, either: set first-weighting-values as values for constructively combining the information that corresponds to the first-frequency-bins of the plurality of antenna-signals; or set first-weighting-values as values for destructively combining the information that corresponds to the first-frequency-bins of the plurality of antenna-signals.

A receiver system comprising: an input terminal configured to receive input signalling comprising a plurality of antenna-signals, wherein the plurality of antenna-signals each comprise information that corresponds to a first-frequency-bin and a second-frequency-bin. AoA-blocks can determine a first-angle-of-arrival and a second-angle-of-arrival associated with the first- and second-frequency-bins. A first-weighting-determination-block configured to, based on the first-angle-of-arrival and the second-angle-of-arrival, either: set first-weighting-values as values for constructively combining the information that corresponds to the first-frequency-bins of the plurality of antenna-signals; or set first-weighting-values as values for destructively combining the information that corresponds to the first-frequency-bins of the plurality of antenna-signals.

Methods and apparatus for determining an angle of arrival in a radar warning system that uses tracking to provide a more accurate angle of arrival than conventional systems. In exemplary embodiments, angle of arrival and range are mapped from measured body angles to a 3D coordinate system where modern tracking techniques are applied to improve accuracy and stabilization of measurements, then mapped back into body angles for display.

Methods and apparatus for determining an angle of arrival in a radar warning system that uses tracking to provide a more accurate angle of arrival than conventional systems. In exemplary embodiments, angle of arrival and range are mapped from measured body angles to a 3D coordinate system where modern tracking techniques are applied to improve accuracy and stabilization of measurements, then mapped back into body angles for display.

Directional antennas comprising substantially identical radiation patterns separated in a horizontal plane by an index angle. A line of bearing to an emitter is determined by a ratio of the power level of an EM signal received by the directional antennas and comparing it to a lookup table to determine an angle off of the boresight of the directional antenna with the highest received power level of the EM signal toward the directional antenna with the second-highest received power level of the EM signal that the emitter of the EM signal is located.

Systems and methods relating to air traffic control and navigational aids for aircraft. An antenna system uses a multi-sector sensor that uses two vertical column antenna arrays per sector. Each pair of vertical column antenna arrays produces two beams that are off a boresight for each pair of antenna arrays. Wide angle monopulse processing is used to determine an azimuth or angle of arrival for an aircraft using at least one pair of the vertical column antenna arrays. Predetermined correction factors are applied to the azimuth for specific elevation values and, for elevation values without predetermined correction factors, interpolation between known predetermined correction values to arrive at the corrector factor to be applied.