High gain directional antenna

　　The following is a detailed analysis of the High Gain Directional Antenna, covering its principles, design points, typical applications and selection guide:

　　1. Core definition and principle

　　Basic concept:

　　Directional radiation concentrates energy in a specific direction, significantly improving signal strength (gain ≥10dBi) while suppressing signal reception in other directions.

　　Working principle:

　　Beamforming: Use antenna arrays (such as multiple radiating units) or physical structures (such as parabolic reflectors) to focus electromagnetic waves in a certain direction.

　　2. Mainstream types and comparisons

　　Antenna type Features Typical gain Applicable scenarios

　　Parabolic antenna - The reflective surface focuses electromagnetic waves, with a gain of up to 15–30dBi.

　　Need to be aligned with the signal source (such as a satellite). | 15–30dBi | Satellite communications, radar, microwave relay stations |

　　| Yagi antenna | - Consists of multiple directional dipoles, with a gain of 8–12dBi and strong directivity.

　　Portable and easy to install. | 8–12dBi | Short-range directional communication, amateur radio |

　　| Helical antenna | - Helical structure supports wide bandwidth, gain 10–20dBi.

　　Suitable for rotation scanning scenarios. | 10–20dBi | UAV navigation, radar detection |

　　| Yagi-Uda antenna | - Improved Yagi antenna, gain up to 10–15dBi.

　　Optimize directivity by adjusting the reflector. | 10–15dBi | FM broadcast, Wi-Fi signal enhancement |

　　3. Key design points

　　3.1 Material selection

　　Conductor: gold-plated copper (low loss), aluminum (lightweight).

　　Dielectric/substrate:

　　FR-4: low cost, suitable for low frequency (<5GHz).

　　PTFE/Teflon: excellent high frequency performance (>10GHz), low dielectric loss.

　　Reflection layer:

　　Metal coating materials (such as aluminum foil, copper mesh) are required for parabolic antennas.

　　(D is the diameter of the parabola).

　　Feed source matching: A feed antenna (such as a horn antenna) compatible with the focus of the parabola needs to be selected.

　　Yagi antenna:

　　Dipole spacing optimization: The spacing between adjacent units is usually λ/2~λ (λ is the wavelength).

　　Reflector tilt adjustment: Reduce rear signal leakage.

　　3.3 Impedance matching

　　Use a π-type network or a T-type network to match the antenna and the RF front end (such as an amplifier).

　　Simulation tools: HFSS, ADS optimize the standing wave ratio (VSWR ≤1.5).

　　4. Typical application scenarios

　　Satellite communication:

　　Ground stations receive satellite signals (such as C-band, Ku-band).

　　Radar system:

　　Millimeter wave radar (77GHz) is used for autonomous driving target detection.

　　Wireless backhaul:

　　Millimeter wave relay between 5G base stations (28GHz/39GHz).

　　Amateur radio:

　　Long-distance HF/VHF communication (such as DX weak signal reception).

　　Industrial detection:

　　Signal enhancement of laser radar (LiDAR) and infrared thermal imaging systems.

　　5. Selection Guide

　　5.1 Frequency Range

　　Low frequency (<1GHz): Yagi antenna, Yagi-Uda antenna.

　　High frequency (>2GHz): parabolic antenna, microstrip array antenna.

　　5.2 Gain requirements

　　Weak signal environment (such as mountainous areas, indoors): gain ≥15dBi (parabolic antenna).

　　Short and medium distance communication (<10km): gain 8–12dBi (Yagi antenna).

　　5.3 Installation conditions

　　Fixed installation: parabolic antenna (precise alignment required).

　　Mobile scenario: helical antenna, vehicle-mounted directional antenna (mechanical rotation mechanism required).