What is the difference in radiated power between a lossless antenna with gain and an isotropic radiator driven by the same power?
The power radiated from the directional antenna is increased by the gain of the antenna
The power radiated from the directional antenna is stronger by its front-to-back ratio
They are the same✓Correct answer
The power radiated from the isotropic radiator is 2.15 dB greater than that from the directional antenna
Explanation
A lossless antenna cannot create power; gain describes how the same transmitter power is concentrated into some directions at the expense of others. Integrated over the whole sphere, the directional antenna and the isotropic radiator radiate identical total power.