Point-to-Point Microwave Link (FDD)
Signal Chain Walkthrough
A point-to-point microwave link provides high-capacity data transport between two locations using frequency-division duplexing (FDD). Each end transmits on one frequency and receives on another, enabling full duplex operation.
Diplexer
A diplexer (bandpass filter pair) separates the TX and RX frequency bands, allowing both to share a single antenna. The TX band is typically separated from the RX band by the duplex spacing (e.g., 300 MHz at 18 GHz). The diplexer must provide high isolation (>70 dB) to prevent TX power from desensitizing the receiver.
Frequency Plan
The near end transmits on frequency f1 and receives on f2. The far end does the opposite: transmits on f2 and receives on f1. Standard frequency plans are defined by ITU-R and regional regulators for bands from 6 to 86 GHz.
Link Budget
Range depends on antenna gain, TX power, receiver sensitivity, and atmospheric conditions. Typical links achieve 10-50 km at 6-23 GHz, with shorter ranges at higher frequencies due to rain attenuation.
Component Specifications
| Component | Parameter | Typical Value |
|---|---|---|
| Frequency Bands | Range | 6 - 86 GHz |
| Diplexer | Isolation TX-RX | > 70 dB |
| PA | Output Power | +20 to +33 dBm |
| LNA | Noise Figure | 1.5 - 3.5 dB |
| Antenna | Gain | 30 - 45 dBi |
| Capacity | Data Rate | 100 Mbps - 10 Gbps |
| Range | Typical | 1 - 50 km |