Which factor does NOT limit angular resolution?

Which factor does NOT limit angular resolution?

• A. Transmit power
• B. Array aperture
• C. Element spacing
• D. Mutual coupling

Answer: (B)

Angular resolution is about how finely you can distinguish two directions, which is set by the width of the radar’s main beam. The beam width depends on wavelength and the size of the antenna aperture: a larger aperture or a shorter wavelength produces a narrower main lobe and better angular resolution. A common rule of thumb is the main-lobe width is roughly proportional to lambda over D (for simple geometries, theta ~ lambda / D). Transmit power mainly affects how far you can detect targets and how strong the returned signal is (signal-to-noise), not how wide the beam is. So power does not determine angular resolution. Element spacing shapes the array factor. If spacing is too large, grating lobes can appear, which create false directions and degrade angular discrimination. If spacing is kept appropriately small (typically around half a wavelength or less), grating lobes are suppressed and the resolution is set by the overall aperture size. Mutual coupling between elements alters each element’s effective excitation and the resulting radiation pattern, which can blur the main lobe or distort sidelobe behavior, reducing the ability to distinguish close directions. So coupling can limit angular resolution. In short, angular resolution is governed by aperture size and wavelength, while transmit power does not limit it.

Angular resolution is about how finely you can distinguish two directions, which is set by the width of the radar’s main beam. The beam width depends on wavelength and the size of the antenna aperture: a larger aperture or a shorter wavelength produces a narrower main lobe and better angular resolution. A common rule of thumb is the main-lobe width is roughly proportional to lambda over D (for simple geometries, theta ~ lambda / D).

Transmit power mainly affects how far you can detect targets and how strong the returned signal is (signal-to-noise), not how wide the beam is. So power does not determine angular resolution.

Element spacing shapes the array factor. If spacing is too large, grating lobes can appear, which create false directions and degrade angular discrimination. If spacing is kept appropriately small (typically around half a wavelength or less), grating lobes are suppressed and the resolution is set by the overall aperture size.

Mutual coupling between elements alters each element’s effective excitation and the resulting radiation pattern, which can blur the main lobe or distort sidelobe behavior, reducing the ability to distinguish close directions. So coupling can limit angular resolution.

In short, angular resolution is governed by aperture size and wavelength, while transmit power does not limit it.