What is the gain of a booster antenna? That is to say, under the condition of equal input power, the ratio of the power density of the signal generated by the antenna and the ideal radiating unit at the same point in space. Of course, this explanation is a bit confusing. In layman's terms, gain indicates how many times the antenna can amplify the signal. Here comes the problem again. The booster antenna is a passive component that does not require power. How can it be amplified? Isn’t this a violation of the most basic principle of conservation of energy?

Of course, there are many ways of gaining antennas to achieve high gains. Here we talk about the gain principle of rod antennas commonly used in routing. The scientific name of this kind of antenna is called a spiral inverter antenna. From a structural point of view, it is a hybrid structure of a linear oscillator and a spiral inverter. The linear oscillator part is responsible for transmitting the signal, and the spiral inverter is responsible for changing the phase of the signal, so that the two oscillators emit signals with different phases. After this signal is combined, a signal with a larger amplitude is formed. In this way, The signal is enhanced.

However, after the signal is combined, the radiation angle of the beam will become smaller. As a rod antenna, although the radial signal is still covered by 360 degrees, the axial coverage angle is greatly reduced. That is to say, the coverage of the rod-shaped high-gain antenna does not change. (In fact, after multiple phase inversions and attenuations, the attenuation of the signal on the antenna will reduce its transmission function). This is the principle of energy conservation. Decided, but it is equivalent to thinning the entire signal. In this way, the signal coverage is increased, but the coverage height is reduced.