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Subelement O: RADAR— Topic 93: Antennas & Waveguides

Question 3-93O3

Element 3 (GROL)

What happens to the beamwidth of an antenna as the gain is increased? The beamwidth:

Explanation
Antenna gain and beamwidth are inversely related. Gain measures how effectively an antenna concentrates radiated power in a particular direction compared to an isotropic (omnidirectional) antenna. To achieve higher gain, an antenna must focus its radio energy into a narrower angular spread. Imagine a flashlight: a wide beam spreads light over a large area (low gain), while a tightly focused beam directs intense light in one specific direction (high gain). Similarly, for radio waves, increased gain means the antenna is directing more of its available power into a smaller segment of space. This concentration of energy into a smaller angular area is precisely what a decreased beamwidth signifies. Therefore, as the gain of an antenna is increased, its beamwidth must decrease to focus the energy more effectively. Options A, B, and C are incorrect because they suggest either an increase in beamwidth or no effect, which contradicts the fundamental principle of how antennas achieve higher gain.

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