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.

Example embodiments relate to methods and systems for implementing radar electronic support measure operations. A vehicle's processing unit may receive information relating to electromagnetic energy radiating in an environment of the vehicle that is detected using a vehicle radar system. The electromagnetic energy originated from one or more external emitters, such as radar signals transmitted by other vehicles. The processing unit may determine a spectrum occupancy representation that indicates spectral regions occupied by the electromagnetic energy and subsequently adjust operation of the vehicle radar system based on the spectrum occupancy representation to reduce or mitigate interference with the external emitters in the vehicle's environment. In some examples, the vehicle radar system may be switched to a passive receive-only mode to measure the electromagnetic energy radiating in the environment from other emitters.

Techniques for determining an angle-of-arrival of a wireless transmission are provided, including receiving, with a first antenna, at least a first portion of a wireless transmission, determining when a second portion of the wireless transmission will be received, switching to the second antenna to receive the second portion of the wireless transmission, determining an angle of arrival of the wireless transmission based on the first portion and the second portion of the wireless transmission, and outputting the angle of arrival of the wireless transmission.

A directional receiver system may include a receiver, a plurality of receive antenna elements, and a circuit. The receiver may include an input port and an output. The plurality of receive antenna elements may be fixedly configured into a known geometric relationship to each other, and each of the receive antenna elements may be connected to the input port of the receiver. The circuit may be coupled to the output of the receiver, configured to determine time differences at which signals from a source are incident upon the antenna elements, and configured to determine an angular orientation of the source to the receive antenna elements based on the time differences.

The invention includes a method for calibrating at low frequency and in-flight a goniometry apparatus including an antenna array, on board an air carrier. The method includes for an angular position of reception, calibrating the airborne goniometry apparatus at a given frequency, comprising transmitting, by means of a calibration transmitter, at the given frequency and in the direction of the goniometry apparatus, at least two calibration signals, with polarizations orthogonal to each other. The method also includes measuring a response of the antenna array for each of the signals. The invention also includes a system implementing such a method.

A receiver circuit is disclosed. The receiver circuit includes a receiver antenna or a receiver antenna arrays oriented at a receiver orientation angle and configured to receive a plurality of RF signals transmitted from a transmitter circuit including a transmit antenna or a transmit antenna array oriented at a transmitter orientation angle. A controller A) calculates first and second AoAs based on a first signal at a first receiver antenna array, and calculates third and fourth AoAs based on a second signal at a second receiver antenna array, and/or B) calculates first and second AoDs based on a third signal from a first transmit antenna array, and calculates third and fourth AoDs based on a fourth signal from a second transmit antenna array. The controller also determines which of the first and second AoAs is correct, and/or determines which of the first and second AoDs is correct.

A system and method for determining an Angle of Arrival (AOA) for frequency modulated communications. The system may include first and second antennas spaced apart from each other by a distance, and configured to receive wireless communications in the form of a modulated signal. The system may determine a phase difference between the received signals based on one or more samples of a dedicated portion of the received signals, where one or more aspects of the dedicated portion is variable.

Techniques for determining an angle-of-arrival of a wireless transmission are provided, including receiving, with a first antenna, at least a first portion of a wireless transmission, determining when a second portion of the wireless transmission will be received, switching to the second antenna to receive the second portion of the wireless transmission, determining an angle of arrival of the wireless transmission based on the first portion and the second portion of the wireless transmission, and outputting the angle of arrival of the wireless transmission.

A method for locating an interferer is provided. The method includes determining, from one of a time difference of arrival (TDOA) signature and a frequency difference of arrival (FDOA) signature between a first signal received at a satellite at a first location and a second signal received at the same satellite at a second location, a first curve on which the interferer lies, determining, from direction of arrival information generated using signals received from the interferer at a plurality of elements of a linear array on the satellite, a second curve on which the interferer lies, and determining, based on an intersection between the first and second curves, the location of the interferer.

Techniques for determining an angle-of-arrival of a wireless transmission are provided, including receiving, with a first antenna, at least a first portion of a wireless transmission, determining when a second portion of the wireless transmission will be received, switching to the second antenna to receive the second portion of the wireless transmission, determining an angle of arrival of the wireless transmission based on the first portion and the second portion of the wireless transmission, and outputting the angle of arrival of the wireless transmission.