Ivan, understood. Throw is just a commonly used (if misused) term relating to the narrowness of the pattern and how much energy is dispersed at some arbitrary distance vs. focused and continuing in the pattern.

You've mentioned pattern flip before when the two axes are dramatically different. I would suspect that something where one axis is twice as wide as the other axis would suffer from this. So that even if the horn mouth were large enough to maintain a 50 degree vertical at 1.8kHz, at some point it would lose that (and any pretense of associated "throw").

In order to avoid pattern flip if the pattern is twice as wide as it is tall, the horn would need to be twice as TALL as it is wide

Basically the pattern does not get wider in pattern as it goes away from the source-assuming the horn is large enough for the freq of interest.

It will get wider and cover more area.

Also remember that the pattern does not "stop" at the coverage angle. That is just the 6dB down point.

Also depending on the design of the horn, it may or may not have the same pattern at different freq.

Remember also that a horn needs different expansion rates for different freq. THe higher freq need to expand faster than the mid freq and the lower freq need to expand slowest.

When only one source (driver) is on the horn, the expansion rates will not be right for some freq bands.

As usual-there are a lot of variables that describe what is really going on.

An attempt to put some "simple numbers" that hopefully describe the "whole operation" will often result in wrong or only partially correct answers.