Are there space-saving solutions for a waveguide?

[sledox]

Are there space-saving solutions for a waveguide? And how do I know how big my waveguide should be. Can someone explain all this to me? 🙂

 

[GM]

As asked, not IME. 🙁 Dr. Geddes on WGs.

 

[AllenB]

It's not unreasonable to aim for a wavelength across at the crossover.

 

[David Morison]

There is a rule of thumb (which, if contradicted by anything in the thread GM links to, I'll happily abandon) that says the lower frequency limit at which a horn will maintain it's nominal pattern control is 1000000/(nominal dispersion*mouth dimension in inches).
So, if you want narrower coverage at lower frequencies, you need a bigger horn.

 

[GM]

I seriously doubt it, though for the record this is @ -6 dB.

 

[AllenB]

space-saving solutions

Some horns use a conical expansion with a secondary flare, as this guides to a lower frequency for the size.