Radar Direction Finding Using Virtual Antennas and Phase Shifters
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Solution Overview
Problem
Radar systems mounted on vehicle platforms, such as missiles or skimmers, face limitations in determining the direction of electromagnetic radiation sources due to aerodynamic constraints, which restrict the use of multi-polarization antennas, and interferometer techniques suffer from ambiguity and limited antenna separation, affecting the accuracy of azimuth and elevation angle measurements.
Innovation Solution
A radar system employing a pair of linearly polarized antennas for each polarization type, with phase shifters to generate phase-shifted signals, forming virtual antennas that provide multi-polarization capabilities, allowing for accurate determination of direction parameters using monopulse and interferometry techniques, even with limited physical antenna separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interferometer techniques are used for direction finding, then angular information can be obtained, but ambiguity occurs when baseline exceeds half the wavelength
Solution Approach 1:
The system divides the direction finding task into multiple polarization channels (horizontal and vertical), processing signals from each polarization separately to resolve ambiguities that would affect a single-channel system
Solution Approach 2:
The radar system performs multiple functions simultaneously: it determines both azimuth and elevation angles while resolving measurement ambiguities, using the same antenna pair for multiple measurement purposes
2Measurement precision
If long baseline interferometer is used, then measurement accuracy improves, but implementation becomes difficult on airborne platforms
Solution Approach 1:
The system changes the approach from physical baseline length to signal processing techniques, using phase comparison and polarization analysis to achieve high angular resolution without requiring large physical antenna separations
Solution Approach 2:
The patent replaces the mechanical solution of increasing physical antenna separation with an electronic and signal processing solution, using phase shifters and polarization-based interferometry to achieve the same measurement precision
3Reliability
If multi-polarization antennas are used, then target detection capability improves, but aerodynamic constraints prevent their use on vehicle platforms
Solution Approach 1:
Instead of using complex multi-polarization antennas, the system segments the polarization function into separate receiving channels that process horizontal and vertical polarizations independently, allowing the use of simpler single-polarization antennas
Solution Approach 2:
The system achieves multi-polarization detection capability through signal processing and phase shifting rather than through physical antenna design, making the system aerodynamically compatible while retaining target detection capabilities
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
The system enables accurate determination of azimuth and elevation angles with enhanced ambiguity resolution and multi-polarization capabilities, suitable for airborne and space applications, while maintaining aerodynamic feasibility and cost-effectiveness.
Implementation Method 1
Each receiver associated with at least one pair of the antennas includes a phase shifter configured to receive electromagnetic signals, to shift a phase of the received electromagnetic signals, and to generate corresponding phase-shifted electromagnetic signals
Implementation Method 2
The signal processing system is configured for combining the phase-shifted electromagnetic signals which are originated from the pair of the antennas associated with the corresponding phase shifters, with non-shifted signals which are originated from another pair of the antennas
Implementation Method 3
A monopulse radar technique and/or a radar interferometric technique can, for example, be used to gather angle information on a target
Implementation Method 4
A radar phase interferometer is a receiving system that determines the angle of arrival of a wave by a phase comparison of the signals received at separate antennas or separate points on the same antenna
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A system and method for determination of a direction to an object emitting and/or reflecting electromagnetic radiation are described. The system includes a first pair of linearly polarized antennas configured for receiving a polarized signal of a first polarization type and a second pair of linearly polarized antennas configured for receiving another polarized signal of the polarization second type originated from the object. The system also includes four receivers coupled to the linearly polarized antennas of the first and second pairs and a signal processing system coupled to the receivers. Each receiver associated with at least one pair of the antennas, includes a phase shifter to provide a required phase shift to the received polarized signals. The signal processing system is configured to combine the phase-shifted polarized signals with non- shifted signals which are originated from different pairs of the antennas, and to process these signals for generating at least one direction parameter of the object.