In finding the wave solution inside a wave guide, we got that the wave number of the wave inside the guide is given by(adsbygoogle = window.adsbygoogle || []).push({});

[tex]k_g^2=\epsilon \mu\omega^2 -\pi^2\left[ \left(\frac{m}{a}\right)^2+\left(\frac{n}{b}\right)^2 \right][/tex]

where n,m can take any integer value. The pair (n,m) caracterizes the mode of propagation (i.e. the wavelenght of the propagating wave). For frequencies lower than the cutoff frequency [itex]\omega_c_{mn}[/itex], the wave number is purely imaginary and there is no wave propagation along the guide; just some atenuated electroagnetic "disturbance".

This is all pretty clear from a mathematical standpoint, but what physically determines the mode??? Say I'm shooting a wave of a given frequency into a guide. How do I know what n and m are??

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# Another Q about wave guides

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