RFRadar Cross Section (RCS) Explained
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This page clarifies what Radar Cross Section (RCS) is, along with the equation used to calculate it.
Radar Cross Section is a measure of the amount of electromagnetic (EM) energy intercepted by a target and scattered back towards the radar system. Simply put, it quantifies how “visible” an object is to radar.
The radar cross section is defined as the ratio of reflected power to incident power density. It’s also sometimes referred to as the target cross section or supply cross section.
The equation for calculating radar cross section (σ) is:
The unit of measurement for radar cross section is square meters (m²).
Key points
- Larger objects will have higher RCS which makes them easily detectable. Table shows RCS values for different objects.
- Material Composition : Reflections due to material will vary RCS; for example metal will have higher RCS while wood or fiberglass will have lower RCS.
- Shape and Geometry : Objects having flat surfaces and sharp edges will have lower RCS (as they reflect waves away from source) where as one with rounded ones will have higher RCS (as they reflect waves back to radar).
- Radar Absorbent Materials : such materials will reduce RCS significantly.
- Surface features : Protrusions such as antennas or weapon mounts will increase RCS due to introduction of reflecting surfaces.
- Orientation : Energy reflection is affected due to angle at which radar signal strikes the object.
Typical RCS values
| Object | Approx. RCS (m^2) |
|---|---|
| Insect | 0.00001 |
| Bird | 0.01 |
| Human | 1 |
| Small Combat Aircraft | 2-3 |
| Large Combat Aircraft | 5-6 |
| Cargo Aircraft | Up to 100 |
| Frigate (103 m length) | 5000-100000 |
| Container ship (212 m) | 10,000 - 80,000 |
Summary
The Radar Cross Section (RCS) is a measure of how detectable an object is by radar. It plays a vital role in both military and civilian applications.
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