I Don't Understand.

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#82
Twellmann said:
I created a spreadsheet to test the formula.
X is incremented in 5mm steps. Phi is incremented in pi/24 steps.

Three plots are made of the cross-section at the throat, the middle and the mouth.
When Theta_min and Theta_max are equal it shows three concentric circles. As Theta_diff increases the circles become more elliptic and they are being offset to one side.

At first it looks like it works, but at some point they lose their elliptic shape and become something else.

Is this to be expected?
How about the center-axis? Is that supposed to also follow some curve, or should it be a straight line.
Click to expand...

The dimple on the short angle axis concerns me as I would not expect that. How could a dimple occur from my equations?
 
#84
Near circular, but not precisely circles would be my expectation, kind of like egg shaped. But when I looked again those curves are for the 15 x 60 waveguide and at those extreme differences oddities might occur. If the average of the angles stayed at 90 then I would not expect anything but near circles. So 60 x 30 should be better.
 
#85
gedlee said:
Near circular, but not precisely circles would be my expectation, kind of like egg shaped. But when I looked again those curves are for the 15 x 60 waveguide and at those extreme differences oddities might occur. If the average of the angles stayed at 90 then I would not expect anything but near circles. So 60 x 30 should be better.
Click to expand...

Something like this I suppose. It also looks more "natural" or not wrong 🙂
 

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#86
Yes, that looks perfectly correct. Exactly what I would expect. They do appear to be egg shaped rather than elliptical, although they might be elliptical, I'm not sure.

Now try making the vertical different than either horizontal, but I suspect that it needs to be no narrower that the narrowest horizontal.
 
#87
gedlee said:
Yes, that looks perfectly correct. Exactly what I would expect. They do appear to be egg shaped rather than elliptical, although they might be elliptical, I'm not sure.

Now try making the vertical different than either horizontal, but I suspect that it needs to be no narrower that the narrowest horizontal.
Click to expand...

I'm fiddling a little bit with that, but I'm guessing how the other theta(phi) term should look like.

If I define it like: Theta[phi]= Theta_avg-COS(C12)*Theta_diff+COS(2*C12)*Theta_vert

When Theta_vert goes above 0.05Rad the curves get distorted

By looking at R[Phi,x] at a certain x value you can see the profile before it gets wrapped into cartesian space. The Cos(2*theta) term will cause a dip on either side of the center peak.
 

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#89
Twellmann said:
I'm fiddling a little bit with that, but I'm guessing how the other theta(phi) term should look like.

If I define it like: Theta[phi]= Theta_avg-COS(C12)*Theta_diff+COS(2*C12)*Theta_vert

When Theta_vert goes above 0.05Rad the curves get distorted

By looking at R[Phi,x] at a certain x value you can see the profile before it gets wrapped into cartesian space. The Cos(2*theta) term will cause a dip on either side of the center peak.
Click to expand...

C12 is Phi?

I'll have to think about this some more. Maybe its not so simple as I thought.

What would a plot of Theta(phi) look like?
 
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