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If you have a microwave frequency of say 2.45 GHz, would you use that frequency in a simple rectangle cross section waveguide, or do you need to use the "lamdba g" waveguide frequency I've read about and if so, why?

I don't understand why you specify one frequency (2.45 GHz) but possibly calculate for another?

Marcus Müller
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user196795
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1 Answers1

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You use the guide wavelength. This is because the wavelength in the waveguide is different than the wavelength in free space. When a wave travels through the waveguide its wavelength changes. You need to solve Maxwell’s equations with the appropriate boundary conditions in order to determine what the wavelength will be in a specific waveguide.

The frequency remains the same. Saying “lambda g frequency” does not make much sense, because lambda g is the wavelength. You use the wavelength not the frequency.

user110971
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  • Thanks. I'm completely new to microwave engineering. I never studied microwave or RF when I did Elec Eng 30 years ago, so its a steep learning curve. I have a copy of Pozar 4th Ed but sometimes you just need to ask newbie questions so you head off in the right directions. What I was trying to work out was "Where would I find a 1/4 wavelength location in a simple WR430 waveguide?" FUnny how the simple stuff can mess you up..... :-) – user196795 Nov 23 '18 at 04:43