hiFor an isotropic radiator (Antenna) all the power is evenly spread over the surface of a sphere whose radius is the distance from the source. So for your 6 Cm distance all the power is spread over the surface of a sphere radius 6 Cm The area of this is 4πr^2 = 4 * 3.142 * 36 = 452.4 sq cm
So if the transmitter power is 1 watt then the field strength is 1/452.4 Watts per square Cm = 2.2 mW per square Cm For an real antenna you multiply this result by the gain of the antenna with respect to an isotropic antenna. An isotropic antenna is just a concept. It does not physically exist. An antenna achieves it's gain by concentrating the power over a smaller area.
Les
It's directly from the definition of an electric field.hi
Can you explain field strength in terms of Volt Per Meters (V/m)
The strength or intensity of the electric field component of an electromagnetic wave is the difference in voltage present between two points in physical space separated by a linear distance of one meter.Can you explain field strength in terms of Volt Per Meters (V/m)