Antennas are a key component in wireless communication systems that transmit and receive electromagnetic waves. Antennas can be classified into various types according to different classification criteria, and the following are common classifications and typical examples:

1. Classification by operating frequency band

- Longwave/Medium Wave Antennas: Used for broadcasting, nautical communications (e.g., tower antennas).
- Shortwave Antennas: Long-distance communication (e.g., diamond antennas, whip antennas).
- Ultra-short wave (VHF/UHF) antennas: TVs, walkie-talkies, FM radios (e.g. Yagi antennas).
- Microwave antennas: satellite communications, radar (e.g., parabolic antennas, microstrip antennas).
- mmWave/terahertz antennas: 5G, high-speed short-range communications (such as lens antennas).

2. Classification by structural form

- Line antennas
- Monopole antenna (whip antenna): in-vehicle communication, handheld devices.
- Dipole Antenna: Symmetrical oscillator, basic broadcast antenna.
- Spiral Antenna: Satellite communication (circularly polarized wave).
- Face-to-face antenna
- Parabolic antennas: satellite communications, radio telescopes (high gain).
- Horn Antenna: Microwave band, used for feeding or testing.
- Array antennas
- Phased array antennas: radar, 5G base station (beam can be scanned electronically).
- MIMO Antenna: Multiple inputs and multiple outputs to improve communication capacity.
- Microstrip antenna
- SMD Antenna: Miniaturized devices (e.g., GPS modules, mobile phone antennas).

3. Classification by directionality

- Omnidirectional antennas: 360° radiation in the horizontal plane (e.g., vertical dipole, whip antenna).
- Directional Antenna: Concentrates energy in a specific direction (e.g., Yagi antenna, parabolic antenna).

4. Classification by polarization

- Line polarization: Vertical/horizontal polarization (like TV receiving antennas).
- Circular polarization: spiral antennas, some satellite antennas.
- Elliptic polarization: A compromise in complex scenarios.

5. Classification by application scenario

- Mobile communication antennas: base station antennas (multi-band), mobile phone built-in antennas.
- Radar Antenna: Mechanically scanned or phased array radar.
- RFID Antennas: Near-field communication (such as access control systems).
- IoT Antennas: Low-power narrowband antennas such as LoRa and NB-IoT.

6. Special type of antenna

- Smart Antenna: Adaptive tuning beam (like 5G Massive MIMO).
- Leakage of coaxial antennas: Closed environments such as tunnels and subways.
- Fractal Antenna: Miniaturized multi-band design (e.g., mobile phone antenna).

Key factors in choosing an antenna

- Frequency range: matches the operating frequency band.
- Gain and directionality: Coverage distance and angle requirements.
- Size and weight: Limited by installation space.
- Environmental Adaptability: Waterproof, wind resistant, etc. (such as outdoor base station antennas).

Different application scenarios require a trade-off between performance and cost, such as satellite communication requiring a high-gain parabolic antenna and IoT devices may opt for micro-patch antennas.