microwave calculators noise figure

microwave RF information for engineers encyclopedia calculators tools

skin depth cpw calculator pin diode

directional coupler smith chart microwave dictionary

October 20, 2017
phased array frequency meter

microwave jobs career recruiting antennas twitter

bandwidth microwave measurements

noise figure phase shifter microwave encyclopedia

s parameters waveguide variable attenuator acronyms

internet of things ios attenuator calculator

Rectangular WG transitions - which Z applies?

1 year 1 month ago - 1 year 1 month ago #670 by sricha1217
sricha1217 created the topic: Rectangular WG transitions - which Z applies?
Hello All: Which formula for the characteristic impedance of rectangular waveguides (air filled, and operating in TE10) applies when attempting to determine the impedance mismatch that occurs when one waveguide abruptly transitions to another?

Using the familiar "wave impedance" formula doesn't make sense because that implies that the impedance depends only on the waveguide width. If that were the correct formula to use to calculate the mismatch between two waveguides, then if one waveguide transitioned abruptly in to another of equal width but different height, there would be no reflection. Intuitively, it is obvious that that cannot be true, because if it were, then a stub or iris placed along the broad face of a waveguide (which effectively shortens the waveguide at that point, but does not affect its width) would have no effect.

Edit: I should point out that I am only interested in reflection coefficients, so I only need to know the best way to determine the proportionality of the waveguide impedances, not necessarily the absolute values. As long as I have a way of determining Z2/Z1 based on their dimensions, I can easily determine: Rho=(Z2/Z1-1)/(Z2/Z1+1).

The "wave impedance" formula effectively sets the impedance of a waveguide proportional to Lambda_g which, at any particular frequency, is determined only by the width, not the height. But I have also seen a formula for impedance proportional to (b/a)*Lambda_g, and another proportional to b*Lambda_g.

Thanks very much for any assistance.
Last Edit: 1 year 1 month ago by sricha1217. Reason: Follow up:

Please Log in or Create an account to join the conversation.

1 year 3 weeks ago #675 by UnknownEditor
UnknownEditor replied the topic: Rectangular WG transitions - which Z applies?
This is probably not the answer you want, but you can "compute" the mismatch using 3D EM analysis tools....

Here is my favorite report on waveguide misalignment/tolerance which might be helpful as a way to check the formulas you develop:


Good luck, and please consider "publishing" some of your results on Microwaves101.


Please Log in or Create an account to join the conversation.

Time to create page: 0.123 seconds
mobile app designers california