Plan reliable point‑to‑point links across demanding sites today. Enter distance, frequency, power, and losses quickly. Get received level, margin, and exportable results instantly here.
| Scenario | Distance (km) | Frequency (GHz) | Tx Power (dBm) | Ant Gains (dBi) | Total Losses (dB) | Rx Power (dBm) | Margin (dB) |
|---|---|---|---|---|---|---|---|
| Baseline backhaul | 12.5 | 11 | 20 | 31 / 31 | FSPL + 1.5 + 1.5 + misc | ≈ -56.4 | ≈ 18.6 |
| Short link | 3.0 | 18 | 17 | 28 / 28 | FSPL + 3.0 (all losses) | ≈ -44.6 | ≈ 25.4 |
| Rain design | 10.0 | 23 | 20 | 33 / 33 | FSPL + rain 2.0 dB/km | ≈ -63.0 | ≈ 12.0 |
Numbers are illustrative; always verify with equipment datasheets and path profiles.
Temporary offices, cranes, and phased workfronts often force microwave hops to change alignments and lengths. A path budget turns “will it work?” into measurable values: received level (dBm) and margin (dB). For many point‑to‑point deployments, engineers target a positive margin plus an additional fade margin to ride through weather and short‑term obstructions.
Common backhaul bands include roughly 6–7 GHz, 11 GHz, 18 GHz and 23 GHz. Higher frequencies generally increase free‑space loss and are more sensitive to rain, but they enable smaller antennas and higher channel capacity. Lower bands often provide better reach and robustness where long spans and severe weather occur.
Dish antennas commonly provide about 24–38 dBi depending on size and band. Every 3 dB of gain roughly doubles received power, while every 3 dB of extra loss roughly halves it. Keeping feeder runs short, using low‑loss jumpers, and minimizing extra inline devices can preserve several dB of margin.
Atmospheric absorption is usually small at many microwave bands over short distances, but rain fade can dominate, especially above ~18 GHz. Design rain attenuation can range from fractions of a dB/km to multiple dB/km in heavy downpours. Many engineered links aim for ~20–30 dB fade margin for high availability, depending on service criticality and climate.
Even with line‑of‑sight, partial blockage of the first Fresnel zone can introduce diffraction loss and multipath fading. A common rule is to keep at least 60% of the first Fresnel radius clear at the tightest point. Use this calculator’s midpoint check as a quick screen, then confirm with a terrain/profile study before final installation.
Link margin is the received signal level minus the receiver sensitivity for the chosen throughput. A higher margin means more tolerance to fading, misalignment, and weather losses.
Use the sensitivity for your planned modulation and capacity from the radio datasheet. Sensitivity typically improves at lower data rates and degrades at higher capacity settings.
Use vendor planning tools or local rainfall statistics for your region and band. Higher frequencies and intense rain generally require higher dB/km inputs for conservative design.
Targets depend on climate and required uptime. Many deployments use about 20–30 dB for robust service, while low‑critical temporary links may accept less if outages are tolerable.
Larger antennas usually provide higher gain and narrower beamwidth, improving received power and margin. However, they require sturdier mounts and more precise alignment on site.
No. This is a fast engineering estimator. Final design should confirm terrain, clutter, clearance, and multipath risk using a profile tool and verified site heights.
A negative value suggests the link may not meet your availability goal. Consider increasing antenna gain, reducing losses, shortening the hop, lowering frequency, or adjusting throughput and sensitivity.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.