Direction-of-Arrival Sensor Antenna Configuration
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Solution Overview
Problem
Phase-comparison monopulse radars face ambiguity issues in determining the direction-of-arrival of radiation when the separation between receiving antennas exceeds half the wavelength of the signal, limiting the accuracy and coverage of angular measurements.
Innovation Solution
The addition of a third receiving antenna positioned in a specific relationship relative to the existing antennas creates an ambiguity shift, allowing for unambiguous angle determination using a single radar pulse by providing additional phase difference information, which is processed to resolve ambiguities and enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the separation between receiving antennas is increased to maximize angular sensitivity and measurement accuracy, then the angular measurement accuracy is improved, but the field-of-view coverage becomes limited due to phase ambiguity
Solution Approach 1:
The patent resolves the contradiction by transitioning from a one-dimensional antenna arrangement to a two-dimensional configuration. By adding a third antenna positioned at a specific location relative to the first two antennas, the system creates multiple phase comparison paths. This dimensional expansion allows the radar to determine direction-of-arrival unambiguously across a wider field of view while maintaining large antenna separations for high angular sensitivity.
Solution Approach 2:
The third receiving antenna acts as an intermediary element that provides additional phase difference measurements. By comparing the phase differences from multiple antenna pairs (first-second, first-third, second-third), the system can resolve phase ambiguities that would otherwise limit the field of view. This intermediary antenna enables the system to maintain large separations for accuracy while expanding coverage.
2Reliability
If narrow beam antennas are used to solve phase ambiguity, then the field-of-view coverage is limited to avoid ambiguity, but the angular measurement coverage is reduced
Solution Approach 1:
The patent segments the direction-finding function across multiple antenna pairs rather than relying on a single narrow beam. Each antenna pair provides phase difference information for a specific angular sector, and by combining measurements from multiple pairs with different orientations, the system achieves unambiguous direction determination across a wide field of view without requiring narrow beamwidth antennas.
3Adaptability or versatility
If multiple receiving antennas are added to resolve phase ambiguity, then the field-of-view coverage is improved, but the device complexity increases
Solution Approach 1:
The patent applies partial action by adding only one additional antenna (the third antenna) rather than implementing a full array of multiple antennas. This single additional element provides sufficient extra phase comparison paths to resolve ambiguities and expand field of view coverage, avoiding the complexity of more extensive antenna arrays while achieving the desired improvement in adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach removes the compromise between field-of-view coverage and angular measurement accuracy, enabling more robust and accurate direction-of-arrival determination in radar systems, even with large antenna separations, and can be applied to various types of radiation and frequencies.
Implementation Method 1
The key concept of the phase-comparison monopulse technique is to measure the delay of an incoming wave front with a quasi-stationary frequency from a receiving antenna to another, physically separated, receiving antenna. The typical very short time delay is measured by measuring the phase difference of the received wave between the two receivers
Data Source
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AI summary
A sensor for determining a direction-of-arrival of radiation impingent on a sensor which has antennas positioned in a particular set-up different from a rectangle, so that information may be derived between two pairs of the antennas, positioned in corners of a rectangle and additional information may be derived from an additional antenna, combined with one of the antennas of the pairs or another antenna, positioned away from the corners and other predefined lines of the rectangle. The positional relationship between this additional antenna and the other antenna of that pair is pre-determined. In this manner, such as from phase differences between the pairs of antennas, more information may be derived compared to antennas positioned merely at the corners of a rectangle.