Acoustic Horn Design – The Easy Way (Ath4)

I don't know what it is but it is definitely rolling back nicely.
(Different values of a parameter controlling the rollback speed.)

Probably some parametrizable bounds on the maximum rollback angle and/or the minimum radius will be handy.

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Just a try - 1.4" throat, free standing, only ⌀280 mm:
(It's still more on the "spiral" side, I'd prefer it more on the "beamwidth control" side. Now it's possible to freely mix the two.)

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I'm new to all of this, and I've been trying to skim through this thread to catch up, but I feel like I'm missing something. What is the benefit of the "spiral" or "rollback" here? Does it improve the polar response or simply limit the beamwidth? Inspiring work so far!
 
What is the benefit of the "spiral" or "rollback" here? Does it improve the polar response or simply limit the beamwidth?
As I understand it, the rollback "shadows" the edge of the waveguide and lowers the intensity of a reflection and/or diffraction from this edge. As can be observed from the previous pictures, it really smoothens the frequency response. With large enough radius and the amount of rolling back, it's like the edge wasn't there at all.
 
Basically, yes.

My aim now is to determine whether large waveguides benefit from this rollback as much as the smaller ones. For that I first need to implement a quick simulation of circular symmetry which is then solved in seconds or minutes, not hours, as I need to compare a bunch of larger devices.
 
Every now and then, after changing the code, I try to re-generate and run through the whole process this horn just to check it still works as before. It still does 🙂
(This is in an infinite baffle.)

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