Satellite communication at RAF Defford

 I found this board in the museum at Croome in the Severn Valley. I went outside and spotted one of the remaining dishes.

Communication with satellites is line of sight. I teach that they use microwaves because the wavelength will pass right through the Earth's atmosphere. The wavelengths of electromagnetic radiation that will do this are limited. But the dish in the picture is so much bigger than a domestic television dish. Why might that be? In astronomy, I teach about what they call the GATHERING POWER or COLLECTING POWER of a telescope. The bigger the area the more Watts of power are collected. In terms of an optical telescope, it means that the image is brighter. That may be what is going on here.