WiFi antennas are critical components in wireless local area network (WLAN) devices. Their core function is to send (radiate) and receive radio wave signals to enable wireless communication between devices (such as routers, mobile phones, laptops, and smart home devices).

Imagine the antenna as the "mouth" and "ears" of wireless signals:

Sending signals (TX): When your device (such as a mobile phone) needs to transmit data, the antenna converts the electrical signals generated by the internal circuit of the device into electromagnetic waves (radio waves) and radiates them effectively into space.

Receiving signals (RX): When data needs to be received from other devices (such as wireless routers), the antenna is responsible for capturing electromagnetic waves in space and converting them back into electrical signals for the internal circuit of the device to process.

Key features and functions:

Signal coverage and strength: The design and performance of the antenna directly affects the transmission distance and strength of the WiFi signal. Antennas with higher gain (usually measured in dBi) can radiate signal energy more concentratedly in a specific direction, thereby obtaining a longer transmission distance or stronger signal penetration in a specific direction (but the coverage angle may become narrower).

Signal Directivity:

Omnidirectional antennas: Most commonly found in home routers. They radiate/receive signals evenly 360 degrees horizontally, providing all-round coverage, suitable for scenarios where multiple rooms or floors need to be covered. Signal strength decreases evenly with distance.

Directional antennas: Concentrate signal energy in a relatively narrow specific direction (beam) for transmission and reception. This can significantly increase the transmission distance and anti-interference ability in a specific direction, and is often used for point-to-point bridging (such as connecting two buildings) or when the signal needs to be enhanced in a specific area (such as the end of a long corridor). Common types of directional antennas include Yagi antennas, flat antennas, parabolic antennas, etc.

Frequency support: Modern WiFi antennas need to support specific operating frequency bands (such as 2.4 GHz, 5 GHz, and even 6 GHz for WiFi 6E/7). Dual-band or multi-band antennas can work in multiple frequency bands at the same time and are compatible with different WiFi standards (such as 802.11n/ac/ax).

Polarization: The electromagnetic waves radiated by the antenna have a specific electric field direction (polarization), such as vertical polarization, horizontal polarization or circular polarization. In order to obtain the best transmission effect, the polarization modes of the communicating parties should be matched as much as possible. Most WiFi devices use vertically polarized antennas.

Common forms and applications:

Built-in antenna: Integrated inside the device (such as mobile phones, laptops, most home routers), usually small in size, mostly omnidirectional or weakly directional design.

External antenna: Exposed to the outside of the device, usually connected through an interface (such as RP-SMA). This provides replaceability, and users can choose antennas with different gains and different directivities according to their needs (such as enhanced coverage, directional connection). Commonly used in high-performance routers, wireless network cards, access points (APs) and bridge devices.

Multi-antenna system: Modern WiFi devices (especially routers that support MIMO technology) are usually equipped with multiple antennas (such as 2x2, 3x3, 4x4). These antennas work together to use spatial stream technology to simultaneously transmit and receive multiple data streams, greatly improving the speed, capacity and reliability of wireless networks.