6G Terahertz Link Budget Calculator

Inputs

Use this for short-range terahertz links supporting automation, telemetry, and high-density job-site connectivity.

Frequency *

Typical research bands: 0.1–1.0 THz.

Bandwidth *

Noise increases with bandwidth.

Distance (m) *

For THz, tens to hundreds of meters are common.

Transmit power (dBm)

dBm is power referenced to 1 mW.

TX antenna gain (dBi)

High gain is typical for narrow beams.

RX antenna gain (dBi)

Keep alignment tight for stability.

TX cable loss (dB)

Feedline and connector losses.

RX cable loss (dB)

Include down-converter insertion loss.

TX misc loss (dB)

Filters, waveguides, couplers.

RX misc loss (dB)

Front-end losses and mismatch.

Atmospheric absorption (dB/km)

Depends strongly on frequency and humidity.

Rain attenuation (dB/km)

Useful for outdoor site corridors.

Penetration loss (dB)

Containers, partitions, glazing, dust covers.

Foliage loss (dB)

Temporary trees or landscaping barriers.

Pointing loss (dB)

Beam misalignment from vibration or sway.

Polarization mismatch (dB)

Accounts for polarization errors.

Other losses (dB)

Scattering, dust, radomes, safety covers.

Noise figure (dB)

Lower is better; depends on front-end.

System temperature (K) *

290 K is a common reference.

Required SNR (dB)

Depends on modulation and coding.

Implementation margin (dB)

Hardware impairments and estimation error.

Fade margin (dB)

Covers blockage, vibration, and variability.

Estimate maximum distance for a target margin

Target margin (dB)

0 dB means “just meets the requirement”.

Range search max (m)

Search is limited to protect performance.

Reset

Example Data Table

Scenario	Frequency	Bandwidth	Distance	TX Power	Antenna Gains	Absorption	Received Power	SNR	Link Margin	Capacity
Temporary crane telemetry backhaul	0.300 THz	2.0 GHz	200 m	10 dBm	35/35 dBi	5 dB/km	-54.01 dBm	19.98 dB	-2.02 dB	13.30 Gbps
Short indoor corridor, cleaner air	0.300 THz	1.0 GHz	100 m	10 dBm	35/35 dBi	2 dB/km	-44.79 dBm	32.12 dB	10.12 dB	10.68 Gbps
Outdoor, more loss and alignment risk	0.600 THz	2.0 GHz	250 m	13 dBm	40/40 dBi	10 dB/km	-55.87 dBm	18.12 dB	-3.88 dB	12.08 Gbps

These rows are illustrative. Use measured attenuation whenever possible.

Formula Used

Free-Space Path Loss

Using frequency in GHz and distance in km.

FSPL(dB) = 92.45 + 20·log10(f_GHz) + 20·log10(d_km)

Received Power

Accounting for gains and all losses.

EIRP = Ptx + Gtx − Ltx

Pr = EIRP − (FSPL + Latm + Ladd) + Grx − Lrx

Noise Power

Bandwidth in Hz; temperature in Kelvin.

N(dBm) = −174 + 10·log10(BW) + NF + 10·log10(T/290)

SNR and Link Margin

SNR(dB) = Pr − N

Margin = SNR − RequiredSNR − ImplMargin − FadeMargin

Throughput Estimate (Upper Bound)

Shannon capacity is an optimistic limit.

C = BW · log2(1 + 10^(SNR/10))

Construction note: Pointing loss and fade margin matter when masts, cranes, or lifts move. Use conservative margins for safety-critical telemetry.

How to Use This Calculator

Enter frequency, bandwidth, and the planned link distance.
Set transmit power and antenna gains for both ends.
Add cable and miscellaneous losses from connectors and hardware.
Include atmospheric absorption and rain attenuation if outdoors.
Use pointing loss for vibration, sway, and alignment tolerance.
Specify noise figure, temperature, and required SNR for your waveform.
Choose implementation and fade margins appropriate for the site.
Press Calculate to view results above the form.
Download the computed report as CSV or PDF if needed.

Terahertz planning for dense job sites

Terahertz links enable short-range, fiber-like backhaul for construction zones. Use them to connect crane sensors, autonomous haul routes, and temporary offices where trenching is costly. This calculator converts frequency and distance into a practical budget so teams can compare alternatives quickly. It helps during preconstruction, when layouts change and feasibility checks guide where to stage radios.

Accounting for propagation losses

Free-space loss rises with both frequency and distance, so even small range increases matter. Add atmospheric absorption to reflect humidity and oxygen lines, then include rain attenuation for exposed corridors. Extra losses capture penetration through site trailers, dust covers, safety glazing, and temporary partitions. When possible, measure attenuation with a trial link and adjust dB/km inputs to match local conditions.

Managing alignment and blockage risk

Narrow beams deliver high antenna gain but demand precise pointing. Vibration from lifts, mast sway, and rotating cranes can introduce misalignment loss, so include a realistic pointing term. For busy sites, fade margin should cover sudden obstructions from moving equipment, scaffolding, and personnel. Consider redundant paths for critical controls, and keep antennas above blockage heights.

Noise, bandwidth, and throughput expectations

Wider bandwidth increases noise power and can reduce SNR if transmit resources are fixed. The calculator estimates noise using bandwidth, receiver noise figure, and system temperature. Shannon capacity is reported as an upper bound to help benchmark design targets; real throughput will be lower after overhead and coding choices. Use capacity and spectral efficiency outputs to sanity-check backhaul needs for cameras, LiDAR, and BIM updates.

Using margins for reliable operations

Link margin summarizes whether the design meets required SNR after implementation and fade reserves. Positive margin supports dependable telemetry and video on dynamic sites, while negative margin suggests reducing distance, narrowing bandwidth, increasing antenna gain, or lowering losses. The optional range search estimates maximum distance for a target margin, which helps place poles, rooftops, or temporary masts. Document assumptions with CSV and PDF exports for design reviews and coordination.

FAQs

1) Why is atmospheric absorption important at terahertz frequencies?

Water vapor and oxygen create frequency-selective attenuation that can dominate short links. Use dB/km values that reflect humidity, temperature, and the selected band to avoid overestimating range.

2) What does EIRP represent in the results?

EIRP combines transmit power and antenna gain minus transmit-side losses. It is the effective radiated level used in the received power calculation and helps compare radios with different antenna systems.

3) How should I choose required SNR?

Pick a required SNR based on your modulation and coding target, plus desired packet error performance. If unknown, start conservative, then refine after lab testing or vendor specifications.

4) Why does increasing bandwidth sometimes reduce link margin?

Noise power grows with bandwidth, so SNR may drop if received power stays constant. Wider channels can still increase capacity when SNR remains high, but margins must be checked.

5) What system temperature value should I use?

290 K is a common reference for typical receivers. Use higher values if your front-end, mixers, or environment add noise, especially for compact enclosures exposed to heat.

6) How does the maximum-distance estimate work?

When enabled, the tool searches for the farthest distance that meets your target margin, keeping all other inputs fixed. It is a planning aid for antenna placement, not a substitute for site surveys.