Microwave Communication - Engineering

Q1:

Which TM mode in rectangular waveguide has lowest cutoff frequency?

A TM11

B TM01

C TM10

D TM21

ANS:A - TM11

Hz = 0 Ex = ± ZTM Hy Ey = ± ZTM Hx where E0 is the amplitude of the wave. The expressions for β, λc, fc, λg, a are the same as for TE waves. For TM wave the lowest cut off frequency in rectangular wave guide is for TM11 mode. If , the cutoff frequency for TM11 mode is about 12% more than that for TE20 mode.