Axial resolution improves with _____ frequency.

Axial resolution improves with _____ frequency.

• A. Increasing
• B. Decreasing
• C. Constant
• D. Inverse

Answer: (A)

Axial resolution depends on the spatial pulse length along the beam. Shorter pulse length allows the system to distinguish two reflectors that are closer in the direction of the beam. Spatial pulse length is the number of cycles in the pulse multiplied by the wavelength. Wavelength is inversely related to frequency (λ = c/f in a medium), so increasing frequency shortens the wavelength. With the same number of cycles in the pulse, a higher frequency shortens the spatial pulse length, which improves axial resolution. Keep in mind that higher frequency reduces penetration depth, a common trade-off.

Axial resolution depends on the spatial pulse length along the beam. Shorter pulse length allows the system to distinguish two reflectors that are closer in the direction of the beam. Spatial pulse length is the number of cycles in the pulse multiplied by the wavelength. Wavelength is inversely related to frequency (λ = c/f in a medium), so increasing frequency shortens the wavelength. With the same number of cycles in the pulse, a higher frequency shortens the spatial pulse length, which improves axial resolution. Keep in mind that higher frequency reduces penetration depth, a common trade-off.