Slotted waveguide antenna software

Hi everyonw
I am finding software which can help design slotted waveguide antenna. Of course i know that CST or HFSS can help, but this takes tons of time.
I have found that TASWAPW, swan-soft.com,.. both of them have softwave to design very quickly. But I can not find the free version.
So anyone can help me in this field
thank you very much for your reading