Why are antennas needed?
You don't have to be a radio technician to answer this simple question. Everyone knows that neither a radio nor television can work without an antenna. Also, a wireless access point does not work without an antenna, which in this case functions simultaneously as a receiver and transmitter. An antenna is both the transmitter of radio waves and its receiver. The antenna configuration determines the coverage area of the wireless access point, that is, the area in which the access point transmits a signal that other wireless clients can receive. We highlight: The coverage area of a wireless access point is determined by the design and not by the size of the antenna, so the principle "the longer the better" does not apply in this case.
The main problem with most standard antennas, that is, antennas that come with wireless access points, is that they do not have a large enough coverage area. For example, if an access point in a room (office) can ensure the liable operation of wireless clients, a stable connection with a client behind the wall cannot be expected. And not all access points will be able to "go through" two walls.
It seems that the problem can be solved easily; just buy an access point with higher transmitting power. However, it is not that simple. The fact is that the transmission power of WLAN devices is strictly regulated. Particularly in the frequency range of 2400 to 2483.5 MHz (the frequency range of WLAN devices), transmitters with a radiation power corresponding to the isotropic radiation power (EIRP) can be used without a license to configure radio networks (term explained below), no more than 100 mW. If this indicator is exceeded, approval must be obtained from the Ministry of Communications for the construction and operation of a departmental data radio network. Consequently, wireless access points and adapters have a transmit power of more than 100 mW, which corresponds to 20 dBm (how these units are related to each other,
So all wireless access points and adapters have the same transmission power, and therefore the only way to cover a wireless network is to use special antennas instead of traditional standard antennas.
44 Increasing wireless coverage is just one of the functions of WiFi antennas to change the shape of the area coverage and thus increase the security of the wireless network. It not only spreads in your apartment but also through the wall to your neighbour, which of course, allows you not only to detect your wireless network quickly but also to try to attack it. And if your neighbour at home probably doesn't have WiFi or at least a laptop with a WiFi adapter, then this situation is quite real in an office building where multiple offices of different companies are on the same floor. Therefore, by neighbours, we mean neighbours not only in the apartment but also in the office.
To avoid temptation and protect your wireless network from outside intruders, you can use special directional antennas that send a signal primarily in one direction. As a result, the signal propagation area can be expanded in this direction, and the signal propagation in other directions can be weakened or blocked. In this case, the difference between a conventional, uniformly Omnidirectional antenna and a directional antenna is roughly the same as between a light bulb and a flashlight. Imagine a light bulb illuminating a room. The light is distributed evenly in all directions, illuminating the room. However, the same bulb can also be inserted into the flashlight or simply put a mirror reflector behind it. In this case, we obtain directional light propagation. Such a beam does not illuminate the entire room, but it can transmit light at a much greater distance. This is how external antennas work.