Radar Angle Resolution Calculator

Radar Angle Resolution Article

1) Meaning of angle resolution

Angle resolution describes how well a radar separates two targets that are side‑by‑side in direction. It is closely tied to the antenna beamwidth: narrower beams give clearer azimuth discrimination and cleaner mapping.

2) Beamwidth estimate used

This calculator uses the practical relation θ ≈ k·λ/D. Wavelength λ comes from λ=c/f, D is the antenna’s azimuth aperture, and k reflects the beam definition and illumination. Many engineers start with k≈0.88 for a common half‑power estimate.

3) Frequency and wavelength impact

Increasing frequency reduces wavelength, which reduces θ when the aperture is fixed. For instance, keeping D constant while moving from 3 GHz to 10 GHz shrinks λ by about 3.33×, so the beamwidth estimate shrinks by the same factor.

S‑band is roughly 2–4 GHz, X‑band 8–12 GHz, Ka‑band 26.5–40 GHz, and W‑band 75–110 GHz. At 10 GHz with D=0.60 m and k=0.88, θ≈2.52°.

4) Circular and rectangular apertures

A circular dish uses diameter as D, while a rectangular panel uses the width in the pointing axis as D. Panels can have different azimuth and elevation widths; this tool focuses on azimuth. Panel height is included to estimate area for a gain check.

5) Cross‑range resolution at distance

To convert beamwidth into a linear separation at range, the calculator applies Δx ≈ R·θ with θ in radians. Example: θ=2° is 0.0349 rad. At R=5 km, cross‑range blur is roughly 5,000·0.0349≈175 m. This helps translate degrees of beamwidth into meters of lateral blur quickly.

6) Design modes for trade studies

If you have a beamwidth requirement, the “required size” mode solves for D at your operating frequency. If your antenna size is fixed, the “required frequency” mode computes what f is needed to meet your target θ. These modes help balance packaging, cost, and spectrum limits.

7) Practical use and reporting

Real antennas deviate from ideal estimates due to taper, scan angle, sidelobes, and manufacturing tolerances. Use k consistently across comparisons, validate units, and export CSV or PDF so your calculations can be reviewed and reused in reports.

Optional: report gain with G ≈ (4π·ηA)/λ²; it does not change θ.

FAQs

1) Which k value should I use?

k≈0.88 is a common half‑power estimate for many apertures. Use a larger k when you need a more conservative beamwidth, or when matching a different beamwidth definition from a datasheet or test report.

2) Can I enter wavelength instead of frequency?

Yes. If wavelength is provided, the calculator derives frequency using λ=c/f. This is convenient when your design notes specify wavelength directly or when you are comparing systems across different bands.

3) Why does cross‑range use radians?

The small‑angle relation Δx≈R·θ requires θ in radians. The tool outputs both degrees and radians so you can read the result in degrees while computing cross‑range distances without unit errors.

4) Does range affect the beamwidth result?

No. Beamwidth is driven mainly by wavelength and aperture. Range only affects the linear cross‑range estimate because Δx scales with R, so the same θ produces a larger blur farther away.

5) What does antenna efficiency change?

Efficiency affects the gain estimate through G≈(4π·ηA)/λ². It does not change the beamwidth calculation directly. Use it for reporting or when comparing two antennas with similar θ but different effective areas.

6) Why include rectangular height if width sets beamwidth?

Width is used as D for azimuth beamwidth. Height is included to compute aperture area for the optional gain estimate. That keeps the beamwidth model simple while still providing a useful performance reference.