Yagi Optimizer is an old DOS program made more than 25 years ago by K6STI made to analyze and design antennas.
It’s very suitable to VHF antenna modelling and even if it is very old it is still very popular.
Nowadays, in the 64Bit era, with the advent of modern Windows versions, running an old MS-DOS program is very hard, but fortunately someone thought to us.
To run MS-DOS programs under Windows you can use DosBox a MS-DOS PC emulator that permits you to easily run Yagi Optimizer , YO.exe without head hakes.
To correctly execute the program follow Mount command instructions when you run DosBox
With Yagi Optimizer you can also use mouse to play with element lengths and element spacing