Low gain where there is destructive interference and high gain where there is constructive interference. That is the feature. Same amount of energy is radiate

Low gain where there is destructive interference and high gain where there is constructive interference. That is the feature. Same amount of energy is radiated, it is just amplified in the high-gain main lobe. A low gain direction is not the same as no signal though. With enough power you can overpower the main lobe signal. https://en.wikipedia.org/wiki/Gain_(antenna) https://en.wikipedia.org/wiki/Gain_(antenna)