題組內容

4. The cutoff frequency of the mode of a rectangular waveguide (with dimensions a and b) is 61dbe428b12df.jpg
m or n= 0, 1,2..., for61dbe44b5e27a.jpg modes (but not both 0) and m or n = 1 , 2..., for61dbe46ea9ba3.jpgmodes.

(Ⅰ) Please determine the lowest five modes for the following cases: (i) b/a=1 (5%);(i) b/a=1/2 (5%); (iii) b/a=1/3 (5%).