1. Outdoor Unit (ODU): Contains the RF transceiver, connected to the antenna. Often mounted directly on the antenna back to minimize waveguide losses.
2. Indoor Unit (IDU): Contains the baseband processing and network interfaces (Ethernet, E1/T1). Connected to the ODU via a coaxial cable or fiber IF cable.
3. Antennas: Typically high-gain parabolic dish antennas. Sizes range from 0.3m to 3.7m diameter depending on the link distance and frequency.
| Advantages | Disadvantages | |------------|---------------| | No digging/right-of-way issues | Requires line-of-sight | | Faster deployment | Weather-dependent (rain fade) | | Lower initial cost for short/medium haul | Limited bandwidth compared to fiber | | Scalable | Frequency licensing required |
Hertzian beam transmission (also known as line-of-sight microwave transmission) uses high-frequency radio waves (typically 1 GHz to 40 GHz) to transmit data between two points without physical cables. It is widely used for backbone telecom networks, TV broadcasting, and backhaul for mobile networks.
| Parameter | Description | |-----------|-------------| | Frequency range | 2 GHz to 38 GHz (common bands) | | Propagation mode | Line-of-sight (LOS) | | Typical distance | 10 km to 50 km (depends on frequency, terrain, and antenna height) | | Key advantage | Low cost vs. fiber, fast deployment | | Key limitation | Sensitive to rain, fog, and obstructions |
A link budget determines if a microwave link is feasible. Key parameters:
Example Simplified Equation:
Received Power (Pr) = Pt + Gt + Gr - Lp - (Other losses)
A professional-grade cours transmission par faisceaux hertziens PDF will generally cover the following modules:
Using digital terrain models (DTM) and software (e.g., Pathloss, ATDI ICS Telecom) to assess clearance over obstacles.
The primary attenuation of the signal occurs due to the spreading of the wavefront as it travels through space. The Free Space Loss ($A_fs$) is calculated using the Friis transmission equation:
$$A_fs (dB) = 92.4 + 20 \log_10(f) + 20 \log_10(d)$$
Where:
