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? 1. One 2. Two 3. Three 4. Four 3–45.    With   the   mode   description, TE_1,1,   what   maximum   number   of half-wave    patterns    exist    across the   diameter   of   a   circular waveguide? 1. One 2. Two 3. Three 4. 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 3-50. 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? 1. A   reflective   load 2. An   absorptive   load 3. An   abrupt   change   in impedance 4. A   gradual   change   in impedance 15