Question

How the effective power radiated by an antenna will be changed if the wavelength of radiation is decreased?

Answer 1

To find how the effective power radiated by an antenna will change if the wavelength of radiation is decreased, we need to find the dependency of effective power on wavelength of radiation. Then check if the wavelength of radiation is reduced then how it will affect the effective power radiated.

Complete answer:
Here, we need to find the dependency of effective power radiated by an antenna on the wavelength of radiation.Radiation from an antenna of length $l$ shows that the power radiated from the antenna is inversely proportional to the square of the wavelength. That is if $\lambda$ is the wavelength of radiation then power radiated is,
$P \propto \dfrac{1}{{{\lambda ^2}}}$
Therefore from the above expression we can say if the wavelength of radiation is decreased then the effective power radiated from the antenna will increase. For example if the wavelength of radiation is reduced by half then the power radiated will increase four times.

Hence, with decrease in wavelength of radiation, the effective power radiated by an antenna increases.

Note: An antenna is a device that has two functions;
-Transmission of signal:- It converts the electrical energy from the transmitter into electromagnetic energy and is radiated into the surrounding environment.
-Receiving of signal:- It receives the electromagnetic energy and converts it into electrical energy.
Antennas are used in our everyday life such as in TV broadcasting, home Wi-Fi network, GPS in cars and highway toll devices.