Antenna & Wave Propagation Quiz 2

What kind of beamwidth is/are produced by Chebyshev arrays for given side lobe level (SLL)?

• Widest

• Narrowest

• Both a and b

If a linear uniform array consists of 9 isotropic elements separated by λ/4, what would be the directivity of a broadside array in dB? (Take the exact expression for the length of array)

• 6.53 dB

• 7.99 dB

• 8.55 dB

• 9.02 dB

Which among the following is regarded as a condition of an ordinary endfire array?

• α < βd

• α > βd

• α = ±βd

  
  

• α ≠ ±βd

If the path difference of two waves with single source traveling by different paths to arrive at the same point, is λ/2, what would be the phase difference between them?

• β x (λ/2)

• β / (λ/2)

• β + (λ/2)

• β – (λ/2)

For a endfire array consisting of several half wave length long isotropic radiators is to have a directive gain of 30. Find the array length and width of major lobe.

• 15λ,7.64°

• 15λ, 8°

• 7.5λ, 59.18°

• 7λ, 67°

Calculate the directivity of a given linear broadside , uniform array of 10 isotropic elements with a seperation of λ/4 between the elements. (Take the approximate expression)

• 4

• 5

• 6

• 10

A uniform linear array consists of 16 isotropic point sources with a spacing of λ/4, if the phase difference δ=-90°, Calculate a) HPBW b) Directivity (c) Effective Aperture (use the exact expression of length of array)

• 42.8°,16, 1.194λ²

• 41.8°, 16, 3.75λ²

• 41.8°, 15, 1.194λ²

• 42.8°,15, 3.75λ²

Design a 7 element broadside array off isotropic sources of λ/2 spacing between elements. The pattern is to be optimum with a side lobe level 19.8 dB down the main lobe maximum.

• 1 1.213 2.225 3.715 2.225 1.213 1

• 1 1.2767 1.6841 1.8392 1.6841 1.2767 1

• 1 1.98 2.97 3.8756 2.98 1.97 1

• 1 1.856 2.9345 3.8756 2.9345 1.856 1