Question

$\text{A parallel plane waveguide has 0.05 m height and it is filled with material having}{\epsilon }_r=\mathrm{2.4.}\text{The frequency range over which there is a single mode propagation lies from zero to\_\_\_\_\_\_GHz.}$

• A. 1.936

Answer 1

The correct option is A 1.936
$v=\frac{c}{\sqrt{{\epsilon }_r}}=\frac{3\times {10}^8}{\sqrt{2.4}}=1.936\times {10}^8\text{m/s}$

The first mode which propagates on parallel plane waveguide is the TEM mode having zero cutoff frequency. For single mode operation.

$f_{c1}=\frac{v}{2a}=\frac{1.936\times {10}^8}{2\times 0.05}=1.936\text{GHz}$