Page:Electronics Technician - Volume 7 - Antennas and Wave Propagation - NAVEDTRA 14092.pdf/119

 3-42. How is the cutoff wavelength for a circular waveguide computed?
 * 1) 1.17 times the radius of the waveguide
 * 2) 1.17 times the diameter of the waveguide
 * 3) 1.71 times the diameter of the waveguide
 * 4) 1.71 times the radius of the waveguide

3-43. The field configuration in waveguides is divided into what two categories?
 * 1) Half-sine and dominant
 * 2) Transverse electric and transverse magnetic
 * 3) Transverse electric and dominant
 * 4) Transverse magnetic and half-sine

3-44. With a mode description of TE$1,0$, what maximum number of half-wave patterns exist across the "a" dimension of a waveguide?
 * One
 * Two
 * 1) Three
 * 2) Four

3-45. With the mode description, TE$1,0$ what maximum number of half-wave patterns exist across the diameter of a circular waveguide?
 * One
 * Two
 * 1) Three
 * 2) Four

3-46. Which of the following devices CANNOT be used to inject or remove energy from a waveguide?
 * 1) A slot
 * 2) A loop
 * 3) A probe
 * 4) A horn

3-47. Loose coupling is a method used to reduce the amount of energy being transferred from a waveguide. How is loose coupling achieved when using a probe?
 * 1) By doubling the size of the probe
 * 2) By increasing the length of the probe
 * 3) By decreasing the length of the probe
 * 4) By placing the probe directly in the center of the energy field

3-48. Increasing the size of the loop wire increases which of the following loop capabilities?
 * 1) Efficiency
 * 2) Bandwidth coverage
 * 3) Power-handling capability
 * 4) Each of the above

3-49. A waveguide that is not perfectly impedance matched to its load is not efficient. Which of the following conditions in a waveguide causes this inefficiency?
 * 1) Sine waves
 * 2) Dominant waves
 * 3) Standing waves
 * 4) Transverse waves

A waveguide iris that covers part of both the electric and magnetic planes acts as what type of equivalent circuit at the resonant frequency?
 * 1) As an inductive reactance
 * 2) As a shunt resistance
 * 3) As a capacitive reactance
 * 4) As a shorted 1/4 wave stub

3-51. A horn can be used as a waveguide termination device because it provides which of the following electrical functions? 14
 * 1) A reflective load
 * 2) An absorptive load
 * 3) An abrupt change in impedance
 * 4) A gradual change in impedance