Radar Receiver
Understanding Radar Receivers
Radar receivers face unique challenges compared to communication receivers. The target echo can be 100-120 dB weaker than the transmitted pulse, clutter returns can be 40-60 dB stronger than the target, and the receiver must operate within microseconds of the transmitter pulse.
Radar Receiver Architecture
- Protection: Limiter/T-R switch protects the receiver from the transmitter pulse.
- LNA: Low-noise amplification of the echo. NF = 2-3 dB typical for modern radar.
- Frequency conversion: Down-convert to IF for filtering and digitization.
- Matched filter: Correlates received signal with transmitted waveform for maximum SNR.
- ADC: Digitize for Doppler processing, CFAR detection, and tracking.
Frequently Asked Questions
What is a radar receiver?
A radar receiver detects weak echo signals from targets. It requires very wide dynamic range (noise floor to strong clutter), matched filtering for maximum SNR, and fast recovery from the transmitted pulse. More demanding than communication receivers.
What is a matched filter?
A matched filter correlates the received signal with the transmitted waveform, maximizing output SNR. For a chirp pulse, the matched filter is a dispersive filter that compresses the chirp into a narrow pulse (pulse compression).
Why is radar dynamic range so demanding?
The receiver must simultaneously handle: strong clutter (mountains, ground) near the transmitter, medium-strength targets (aircraft), and very weak targets (small drones, stealth aircraft). The clutter-to-target ratio can be 40-60 dB.