Solid angle corresponds to one unit of area on the unit sphere surrounding the apex, so an object that blocks all rays from the apex would cover a number of steradians equal to the total surface area of the unit sphere, formula_1. Solid angles can also be measured in squares of angular measures such as degrees, minutes, and seconds. A small object nearby may subtend the same solid angle as a larger object farther away. For example, although the Moon is much smaller than the Sun, it is also much closer to Earth. Indeed, as viewed from any point on Earth, both
Mast radiator as tall as 5/8 wavelength (225 degrees) are somewhat common. Any simple radiator (or array of radiators) which is taller than 195 degrees is generally not considered to have anti-fading properties. A more complex anti-fading antenna is a vertical radiator which is sectionalized and is one wavelength (360 degrees, generally 180 over 180 degrees, and historically and correctly termed a "Franklin" radiator; two in an array at KFBK), or 300 degrees (180 over 120 degrees, and formally called a WHO radiator), or 240 degrees (120 over 120 degrees, and formally called a WOAI radiator, but WOAI has since replaced this