Link budgets and asymmetric links

Question

After transmitter power, equipment losses, antenna gains, and path loss are combined, what reaches the receiver—and how far is it above or below the selected sensitivity?

Inputs

Calculation mode Basic · A to B Advanced · A to B and B to A

Enter non-negative losses as magnitudes. The calculation applies their negative sign. Advanced mode keeps both directions independent because radios, antennas, losses, path loss, and receiver modes may differ.

Endpoint equipment and band checks Optional

Search narrows each list without changing its current selection. Press Down Arrow to move to the matching options.

Find endpoint A radio

Find endpoint B radio

Endpoint A radio Endpoint B radio Find endpoint A antenna

Endpoint A standalone antenna Find endpoint B antenna

Endpoint B standalone antenna Operating frequency MHz · shared-band check Channel width MHz · shared-width check

Endpoint A supplies A’s transmitter context and endpoint B supplies B’s. A→B therefore starts from A TX with B RX, while B→A starts from B TX with A RX. Loading records seeds power; integrated radios seed their antenna gain, while connectorized radios use a compatible standalone antenna gain when selected or keep gain manual. Receiver thresholds remain manual because choosing a radio does not choose a channel width, modulation, or receiver mode. Every numeric value remains visible and editable. Each selected radio and antenna must support an entered frequency, a selected radio pair must share a published band, and an entered channel width must be published for every selected radio. Equipment losses and path loss always remain manual assumptions.

A to BTX power dBmTX equipment loss dB · ManualTX antenna gain dBi · ManualPath loss dB · ManualRX antenna gain dBi · ManualRX equipment loss dB · ManualReceiver threshold dBm · Manual receiver-mode choice

Answer

Enter one direction, or enable advanced mode for two independent directions.

Working

received signal = TX power − TX losses + TX antenna gain − path loss + RX antenna gain − RX losses

fade margin = received signal − receiver sensitivity

Visual explanation

The calculated signal chain will appear here with every contribution signed.

Interpretation

A positive fade margin means the calculated receive level is above the selected receiver threshold. A negative margin means it is below that threshold. This is a threshold comparison, not an availability, capacity, or reliability promise.

Limitations

Model boundaries and input provenance

Calculation source: WISP Planner's canonical Rust link-budget contract owns the signed signal-chain and fade-margin equations shown above.

This lesson accepts a caller-supplied path-loss term. It excludes terrain and Fresnel obstruction, vegetation and building clutter, interference and noise, weather and rain fade, antenna-pattern misalignment, cable or connector behavior not entered above, adaptive radio behavior, channel-width and modulation selection, regulatory limits, and equipment constraints beyond the entered values.

Input provenance: each field identifies whether it came from a selected canonical endpoint record or remains a manual assumption. Recorded source values and checked dates appear above, including “Not recorded” when absent; equipment losses and path loss are never inferred from a product record.

Next step

Plan a link from saved sites

The planner combines saved sites, configured equipment, terrain, buildings, clutter, and propagation analysis.

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Any manual signal-chain terms and lesson equipment selections stay on this page. They are not imported because the planner calculates links from saved topology and configured equipment.

First use the terrain path check to inspect geometry and Fresnel clearance.