Radar Antenna Gain Control Block for Saturation Avoidance
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Solution Overview
Problem
Airborne radars face saturation issues due to high-power echoes from nearby surfaces, leading to increased noise figure and complexity in modern architectures with multiple reception channels, particularly at low altitudes.
Innovation Solution
Implementing an antenna gain control block that adjusts the Equivalent Isotropic Radiated Power (EIRP) based on the current signal level and environmental parameters like altitude and incidence angle, using a regulation loop to maintain the signal level below the saturation threshold and modulate the EIRP to avoid clutter, thereby eliminating the need for upstream Time Variable Gain attenuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Time Variable Gain attenuator is placed upstream to avoid saturation, then saturation is avoided, but the noise factor increases and device complexity increases
Solution Approach 1:
The patent removes the Time Variable Gain attenuator from the upstream signal path and extracts its function to be performed downstream in the digital signal processing chain. This eliminates the need for complex RF attenuators while maintaining saturation avoidance through digital gain control applied to received signals after they have been processed by the receiver chain.
Solution Approach 2:
The patent replaces the mechanical/RF attenuator system with a digital signal processing system. Instead of using physical components to attenuate signals before reception, the invention uses digital processing to apply variable gain control to the received signals, substituting electronic/mechanical attenuation with computational gain adjustment.
2Reliability
If a Time Variable Gain attenuator is placed upstream to avoid saturation, then saturation is avoided, but the noise factor increases
Solution Approach 1:
The patent applies preliminary digital signal processing to the received signals before saturation can occur in downstream processing stages. By performing gain control and signal conditioning in the digital domain immediately after reception, the system prepares signals optimally without introducing the high noise factors associated with upstream RF attenuation.
3Reliability
If upstream attenuation is used to avoid saturation, then saturation is avoided, but calibration complexity increases
Solution Approach 1:
The patent implements a self-calibrating digital signal processing system that automatically adjusts gain parameters based on received signal characteristics. The system performs self-diagnosis and self-adjustment of digital gain control parameters without requiring external calibration equipment or complex manual calibration procedures, thereby simplifying manufacturing and deployment.
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 solution maintains optimal reception levels, reduces noise figure, simplifies radar architecture, and decreases calibration requirements, while improving stealth by dynamically adjusting the EIRP and reducing physical complexity and costs.
Implementation Method 1
a radar emitting electromagnetic waves 31
Implementation Method 2
echoes coming from the surface 30 (ground, sea, etc.) located under the aircraft 20 and reflecting the emitted electromagnetic waves 31
Implementation Method 3
a transmitter-receiver antenna comprising a plurality of radiative elements distributed over a surface and adapted for the transmission and reception of an electromagnetic wave
Data Source
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AI summary
Radar (10) comprising a transmitting-receiving antenna (11) having a plurality of radiating elements (180) adapted for the transmission and reception of an electromagnetic wave, said radar being characterized in that it comprises an antenna gain control block (12), by activation/inhibition of the radiating elements, in transmission and/or in reception adapted to maintain the level of reception of an electromagnetic wave below a determined threshold lower than the saturation zone of the antenna, as well as by activation/inhibition of the radiating elements in reception, adapted to compensate for the variation in amplitude of the ground/sea clutter, over the duration of reception.