pdf to jpg conversion

I am trying to save a PDF as a JPEG in order to use it in illustrator. But when i import the converted file in illustrator the image doesn't keep it's original proportions The height of the image is reduced by approx. 40%. I tried to see if changing the jpg settings in acrobat would fix this but it didn't work.

Also, I tried to import the converted jpg in CAD and the result is the same: the image doesn't keep its original proportions.