Radar antenna beamwidth — preferred for detection and angular resolution For most radar applications, how should the antenna beamwidth be chosen?

Introduction / Context:
Radar systems determine target direction by the pointing of a directive antenna. Angular resolution and clutter rejection depend strongly on beamwidth. Selecting an appropriate beamwidth is a fundamental radar design decision, closely tied to antenna aperture size and operating frequency.

Given Data / Assumptions:

• Narrower beamwidth improves angular resolution and reduces clutter/side illumination.
• Practical limits set by antenna size, frequency, and scanning method.

Concept / Approach:
Beamwidth (approximately proportional to wavelength/aperture) dictates how finely the radar can discriminate two close targets and how much ground/sea clutter enters the receiver. A very narrow beam concentrates energy and sensitivity in a small angular sector, improving detection range (antenna gain) and angle accuracy. Hence, radars strive for the narrowest feasible beam within mechanical and cost constraints.

Step-by-Step Solution:

Verification / Alternative check:
Phased-array radars achieve sub-degree beams via large apertures, illustrating the performance benefits of narrow beams in operational systems.

Why Other Options Are Wrong:

• Very wide: poor angle resolution, high clutter; used only for surveillance with different trade-offs.
• Neither too narrow nor very wide / either (b) or (c): vague and not optimal for most tracking/search radars aiming for high resolution.

Common Pitfalls:
Ignoring sidelobe control; a narrow mainlobe with high sidelobes still invites interference—hence tapering and array weighting are also important.

Final Answer:
very narrow