Link Budget Components
| Parameter | Symbol | Typical Value |
|---|---|---|
| Transmit power | P_tx | +20 to +43 dBm (phone to base station) |
| TX antenna gain | G_tx | 0 dBi (phone) to +18 dBi (panel) |
| EIRP | EIRP | P_tx + G_tx |
| Free-space path loss | FSPL | 100–130 dB @ 1 km cellular |
| RX antenna gain | G_rx | 0 dBi (phone) to +18 dBi (panel) |
| Received power | P_rx | EIRP − FSPL + G_rx − losses |
| Receiver sensitivity | S | −90 to −105 dBm typical |
| Link margin | LM | P_rx − S (must be >0 for connection) |
Sample Link Budget (5G NR n78, 3.5 GHz)
TX side (base station): PA output: +38 dBm Cable loss: −1 dB Antenna gain: +18 dBi (massive MIMO, 64T64R) EIRP: 38 − 1 + 18 = +55 dBm Path (1 km, urban): FSPL: 20·log₁₀(3500) + 20·log₁₀(1) + 40 = 71.9 + 0 + 40 = 111.9 dB Shadow fading margin: −8 dB RX side (UE phone): Antenna gain: +0 dBi Body loss: −3 dB Received: 55 − 111.9 + 0 − 8 − 3 = −67.9 dBm UE sensitivity at 100 MHz BW: −96 dBm Link margin = −67.9 − (−96) = +28.1 dB ✓ (good coverage)
RF View NF Cascade: Compute receiver sensitivity accurately using the NF Cascade Calculator in RF View. Enter each stage NF and gain to get system NF, then compute sensitivity. Free on Android.