Angle of Arrival Estimation Using Phase and Pulse Delay
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Solution Overview
Problem
Widely-spaced antenna arrays in radar systems experience phase ambiguities, leading to grating lobes and reduced angular resolution, which increases costs due to the need for larger apertures and more antenna elements.
Innovation Solution
A method that measures phase differences and pulse delays between signals received by antenna elements to determine a set of possible angles of arrival, resolving ambiguities by selecting the angle with the smallest absolute difference to the estimated time of arrival, thereby calculating an unambiguous angle of arrival.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If antenna elements are widely-spaced to reduce array size and cost, then device complexity and cost are reduced, but phase ambiguities and grating lobes occur leading to reduced measurement precision
Solution Approach 1:
The patent transitions from relying solely on phase difference measurements (one-dimensional approach) to combining phase difference with time delay measurements (adding temporal dimension). This multi-dimensional measurement approach resolves the phase ambiguity problem by providing additional independent information about the signal arrival, enabling accurate angle estimation even with widely-spaced antenna elements.
Solution Approach 2:
The patent creates a composite measurement approach by combining two different measurement techniques (phase difference measurement and time delay measurement) into a unified angle of arrival estimation system. This composite methodology leverages the strengths of both measurement types while compensating for their individual weaknesses, particularly the phase wrapping issue in widely-spaced arrays.
2Area of stationary object
If antenna elements are widely-spaced to reduce aperture size, then area and cost are reduced, but grating lobes appear causing harmful interference and reduced reliability
Solution Approach 1:
The patent converts the potentially harmful effect of widely-spaced antenna elements (which cause phase ambiguities and grating lobes) into a beneficial configuration. By using the widely-spaced geometry combined with time delay measurement, the system achieves the same angular resolution as tightly-spaced arrays while maintaining a smaller aperture. The harmful phase ambiguity is resolved through the additional time delay information.
3Measurement precision
If more antenna elements are used to improve angular resolution, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the antenna elements multi-functional by using them for both phase difference measurement and time delay measurement. Instead of requiring separate measurement systems or additional elements, the same widely-spaced antenna array performs dual measurement functions, achieving high angular resolution with minimal hardware complexity.
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 allows for unambiguous high angular resolution with a reduced number of antenna elements, leading to cost savings and improved radar system performance by eliminating grating lobes and phase ambiguities.
Implementation Method 1
the phase difference between the signals received by the antenna elements is measured and used to establish the signal arrival direction
Implementation Method 2
measuring a pulse delay of the incident plane wave between the signals received at the plurality of receiving channels
Data Source
AI summary
A method is disclosed for determining an angle of arrival of an incident plane wave received by an antenna array. The method includes receiving signals from a plurality of antenna receiving channels, determining a set of possible angles of arrival of the incident plane wave based on the signals received at the plurality of receiving channels, measuring a pulse delay of the incident plane wave between the signals received at the plurality of receiving channels, and calculating the angle of arrival of the incident plane wave based on the set of possible angles of arrival and the measured pulse delay.