Antennas Quiz

1. An antenna's size and shape primarily depend on its ____.

2. An antenna is designed to ____ electromagnetic waves.

3. A hypothetical point source radiates energy ____.

4. The radiated energy can be represented by a traveling waveform following a ____ curve.

5. A single complete cycle of a wave is one ____.

6. An antenna that accommodates approximately half a wavelength is a ____.

7. Feeding a dipole causes electron flow that creates a fluctuating ____ field (H field).

8. The H-field strength is proportional to the amplitude of the current ____ wave.

9. The antenna's time-varying voltage produces an ____ field in phase with it.

10. Near the antenna, E and H fields build and collapse ____ out of phase with each other.

11. The immediate (near) field of the antenna gives rise to the ____ wave pattern that propagates outward.

12. In visualizing traveling waves, vertical lines often denote the ____ component and horizontal lines the ____ component.

13. Traveling waves from an antenna are in time phase and in ____ quadrature.

14. An antenna's polarization is determined by the plane of the ____ field.

15. The direction of propagation is given by the ____ vector rule.

16. When a wave strikes a plane surface, the direction of propagation ____.

17. A polar diagram is constructed by sampling signal strength and joining points of equal ____.

18. A vectorial presentation gives each reading a ____ and ____ in a polar plot.

19. A half-wave dipole produces two fields due to electron flow: the ____ field and the ____ field.

20. Traveling waves radiated by antennas are in time phase and ____ quadrature.

21. In the far field (Fraunhofer), E and H are ____ and fields decay approximately as ____.

22. Reactive near-field extends roughly to r ≲ ____ (in terms of wavelength λ).

23. Antenna gain G equals efficiency η times ____.

24. 0 dBd is approximately equal to ____ dBi.

25. Effective aperture Ae relates to gain as Ae = ____.

26. Friis transmission (free space): Pr = Pt Gt Gr (____)^2 (ignoring other losses). Fill the blank.

27. Polarization mismatch (linear) causes a power factor of cos^2(ψ), where ψ is the ____ between polarizations.

28. A half-wave dipole in free space has an input impedance of approximately ____ Ω.

29. VSWR is given by (1 + |Γ|) / (1 − |Γ|), where Γ is the ____ coefficient.

30. Antenna quality factor Q is approximately f0 divided by ____.

31. Electrically small antennas (ka ≪ 1) typically have ____ bandwidth.

32. A quarter-wave monopole over a ground plane has radiation resistance approximately ____ Ω.

33. For an aperture, larger D (aperture size) generally gives ____ beamwidth.

34. To avoid grating lobes in a wide-scan array, element spacing should be ≤ ____.

35. Phase shift to steer a uniform linear array is approximately φ = 2π d sin(θ) / ____.

36. A dipole is balanced; coax is unbalanced, so a typical feed uses a ____ balun for common-mode suppression.

37. A folded dipole has an input impedance near ____ Ω in free space.

38. Antenna efficiency η equals Prad divided by ____.

39. For a half-wave dipole, current is approximately sinusoidal with a maximum at the ____ point.

40. Due to end effects, a resonant half-wave dipole length is closer to ____ λ than 0.5 λ.

41. The Poynting vector S = E × H indicates the ____ flow direction of an EM wave.

42. Antenna gain referenced to isotropic is measured in ____.

43. Which antenna is known for high front-to-back ratio using parasitic elements?

44. Which antenna type is compact and commonly used on PCBs?

45. A parabolic reflector antenna is typically characterized by ____ gain and a narrow beam.

46. In the near field, localized ____ can occur; exposure limits are governed by MPE/SAR.

47. A VNA measurement of return loss primarily characterizes which parameter?

48. Antenna efficiency can be measured by methods such as the Wheeler cap or ____ comparison.