GATE 2019 EC – Question 61
A rectangular waveguide of width $w$ and height $h$ has cut-off frequencies for TE$_{10}$ and TE$_{11}$ modes in the ratio 1 : 2. The aspect ratio $w/h$, rounded off to two decimal places, is ________.
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 1.72 to 1.74
Explanation
$f_{c,10}=\frac{c}{2w}$ and $f_{c,11}=\frac c2\sqrt{\frac1{w^2}+\frac1{h^2}}$. The ratio gives $\sqrt{1+\frac{w^2}{h^2}}=2$, so $\frac{w}{h}=\sqrt3=1.73$.