Wireless PtP Link Budget & Fresnel Zone Calculator
Calculate received RX signal (dBm), free-space path loss FSPL, 60% Fresnel clearance, earth curvature bulge, and minimum triangle tower heights.
Input Parameters
Calculation Results
- Point-to-Point Link Distance
- 5 km
- Operating Radio Frequency
- 5.8 GHz
- Radio Transmit Power (TX)
- 24 dBm
- Antenna Gain (Dish / Sector)
- 23 dBi
- Obstacle Height (Trees / Building)
- 12 Meters
- Pigtail & RF Connector Loss
- 2 dB
- Free Space Path Loss (FSPL)
- 121.7 dB
- Estimated Received Signal Level (RX)
- -53.7 dBm
- 1st Fresnel Zone Radius (F1)
- 8.04 Meters
- Minimum 60% Fresnel Clearance
- 4.82 Meters
- Earth Curvature Bulge
- 0.37 Meters
- Recommended Minimum Tower Height
- 18 Meters
- Estimated Triangle Tower Sections (@ 5m)
- 5 Sections
- Link Quality & Fade Margin Status
- EXCELLENT (Full Modulation 8x / 256-QAM)
Isolate management, server, user, and IoT/CCTV traffic into dedicated 802.1Q VLANs.
Ringkasan Wireless PtP Link Budget & Fresnel Zone – InfraCalc.web.id Jarak Tembak : 5 km pada Frekuensi 5.8 GHz (FSPL: 121.7 dB) Radio & Antena : TX 24 dBm + 2× Antena Dish 23 dBi Estimasi RX : -53.7 dBm (SANGAT STABIL (Full Modulation 8x / 256-QAM)) Fresnel Zone 1 : Radius 8.04 m (Wajib bebas halangan minimal 60% = 4.82 m + Lengkung Bumi 0.37 m) Tinggi Tower : Minimal 18 Meter di atas tanah (dengan tinggi pohon/gedung tengah 12 m)
Technical Accuracy Note: Calculation results are engineering estimates based on standard RFC/IEEE/ITU-T models. Actual field performance may vary due to protocol overhead, hardware specifications, and environmental factors.
How to Use This Tool
- Enter the straight-line link distance in kilometers (km) and specify the radio carrier frequency (e.g. 5.8 GHz, 2.4 GHz, or 24/60 GHz).
- Input transmitter launch power (dBm), directional dish antenna gain (dBi), and peak midpoint obstruction height above ground.
- Review the predicted received signal level (RX in dBm), link modulation health, 60% Fresnel radius, and minimum tower elevation heights.
Worked Example: Rural PtP Link 5 km @ 5.8 GHz (Dish 23 dBi)
Worked example: A 5 km link at 5.8 GHz using a 24 dBm transmitter paired with dual 23 dBi dish antennas yields a predicted RX signal of -53.7 dBm (EXCELLENT (Full Modulation 8x / 256-QAM)). Factoring in a 12m midpoint tree barrier, 0.37m earth curvature bulge, and 4.82m 60% Fresnel clearance dictates a minimum tower height of 18 meters (±5 triangular tower stages @4m).
- Wireless Link Distance
- 5 km
- Carrier Radio Frequency
- 5.8 GHz
- Radio TX Power
- 24 dBm
- Dish Antenna Gain (Per Side)
- 23 dBi
- Midpoint Obstacle Height
- 12 Meters
- Point-to-Point Link Distance
- 5 km
- Operating Radio Frequency
- 5.8 GHz
- Radio Transmit Power (TX)
- 24 dBm
- Antenna Gain (Dish / Sector)
- 23 dBi
- Obstacle Height (Trees / Building)
- 12 Meters
- Pigtail & RF Connector Loss
- 2 dB
- Free Space Path Loss (FSPL)
- 121.7 dB
- Estimated Received Signal Level (RX)
- -53.7 dBm
- 1st Fresnel Zone Radius (F1)
- 8.04 Meters
- Minimum 60% Fresnel Clearance
- 4.82 Meters
- Earth Curvature Bulge
- 0.37 Meters
- Recommended Minimum Tower Height
- 18 Meters
- Estimated Triangle Tower Sections (@ 5m)
- 5 Sections
- Link Quality & Fade Margin Status
- EXCELLENT (Full Modulation 8x / 256-QAM)
- Material Requirement Summary (Copy-Ready)
- Ringkasan Wireless PtP Link Budget & Fresnel Zone – InfraCalc.web.id Jarak Tembak : 5 km pada Frekuensi 5.8 GHz (FSPL: 121.7 dB) Radio & Antena : TX 24 dBm + 2× Antena Dish 23 dBi Estimasi RX : -53.7 dBm (SANGAT STABIL (Full Modulation 8x / 256-QAM)) Fresnel Zone 1 : Radius 8.04 m (Wajib bebas halangan minimal 60% = 4.82 m + Lengkung Bumi 0.37 m) Tinggi Tower : Minimal 18 Meter di atas tanah (dengan tinggi pohon/gedung tengah 12 m)
Core Concept & Engineering Notes
How It Was Calculated (Formulas & Steps)
Mathematical Formulas
- FSPL (dB) = 20 × log10(Dist km) + 20 × log10(Freq GHz) + 92.45
- Received RX (dBm) = TX + Gain TX + Gain RX - FSPL - Cable Losses (2 dB)
- 1st Fresnel Radius (m) = 8.656 × sqrt(Dist km / Freq GHz)
- 60% Fresnel Clearance = Fresnel Radius × 0.60
- Earth Curvature Bulge (m) = (Dist km²) / 68 at trajectory midpoint
- Minimum Tower Height = ceil(Obstacle Height + Earth Bulge + 60% Fresnel Clearance)
Step-by-Step Calculation
- 1. Free Space Path Loss (FSPL): 20 × log10(5 km) + 20 × log10(5.8 GHz) + 92.45 = 121.7 dB
- 2. Received Signal Power (RX): 24 dBm (TX) + 23 dBi (Ant-TX) + 23 dBi (Ant-RX) - 121.7 dB (FSPL) - 2 dB (Loss) = -53.7 dBm [EXCELLENT (Full Modulation 8x / 256-QAM)]
- 3. 1st Fresnel Zone Radius: 8.656 × sqrt(5 / 5.8) = 8.04 meters
- 4. 60% Mandatory Clearance Zone: 8.04 m × 60% = 4.82 meters
- 5. Earth Curvature Bulge at Mid-point: (5²) / 68 = 0.37 meters
- 6. Minimum Antenna Tower Height: ceil(12 m obstacle + 0.37 m bulge + 4.82 m clearance) = 18 meters above ground
- 7. Triangle Tower Construction: ceil(18 m / 4m stage) = ± 5 triangular tower stages
Frequently Asked Questions (FAQ)
Why is the optimal outdoor wireless RX signal target between -50 dBm and -65 dBm?
Levels between -50 and -65 dBm permit modern radios to unlock highest constellation modulations (256-QAM or 1024-QAM / 8x to 10x data rates) while maintaining an essential 15–20 dB thermal fade margin during rain. Signals hotter than -40 dBm risk front-end receiver saturation, whereas readings below -75 dBm suffer carrier throttling.
What happens when more than 40% of the Fresnel zone is physically obstructed?
When obstacles intrude beyond 40% of the Fresnel radius (leaving less than 60% clearance), reflected electromagnetic waves arrive 180 degrees out of phase, destructively canceling the primary signal. This triggers severe multipath fading, heavy frame discards, and link degradation.
How do you bypass prominent hills or high-rise structures obstructing a PtP path?
Proven engineering remedies include: (1) Increasing tower elevations at both endpoints; (2) Re-siting antenna mounting masts laterally; or (3) Establishing an intermediate active repeater station (back-to-back PtP transceivers) atop the obstructing topography.
Why are 60 GHz and 24 GHz frequencies far more susceptible to rain fade than 5 GHz?
Millimeter-wave frequencies (e.g. 60 GHz with a 5 mm wavelength) match the physical dimensions of falling raindrops and atmospheric oxygen resonance bands. Rain droplets directly absorb and scatter the RF wavefront, limiting 60 GHz deployments to shorter hops (<2 km) paired with 5 GHz failover backup radios.
Related Calculators
View All Network & Routing Tools →Convert RF power between dBm, milliwatts (mW), Watts, and dBW, and calculate Free Space Path Loss (FSPL) attenuation for wireless radio links.
Calculate GPON/EPON optical link loss budget (dBm), passive splitter loss, splicing, and estimate bulk UTP Ethernet cable boxes and RJ45s.
Calculate Wi-Fi access point counts by coverage area and client capacity, PoE switch power budget, and minimum ISP internet line bandwidth.
Calculate PoE Cat6, Cat5e, and CCA cable voltage drop, delivered terminal voltage, safe run distances, and night-time infrared reboot risks.
References & Notes
- ITU-R Recommendation P.526-15 — Propagation by diffraction
- ITU-R Recommendation P.530-18 — Propagation data and prediction methods required for the design of terrestrial line-of-sight systems
- Ubiquiti airLink / airFiber Outdoor Wireless Planning Fundamentals
Note: Results above are mathematical estimates based on standard formulas. Always verify against official vendor documentation and site conditions before production deployment.
🔗Related Scenarios & Companion Calculators
Browse All 30+ Scenarios →⚡ Ready-to-Use Scenario Presets:
Instant /32 CIDR reference: Subnet Mask is 255.255.255.255, Wildcard 0.0.0.0, Total IPs 1, and 1 Usable Hosts. Ideal for OSPF/BGP Router Loopback & Single Host Route.
Instant /30 CIDR reference: Subnet Mask is 255.255.255.252, Wildcard 0.0.0.3, Total IPs 4, and 2 Usable Hosts. Ideal for Point-to-Point Inter-Router WAN Link (2 Usable IPs).
Instant /29 CIDR reference: Subnet Mask is 255.255.255.248, Wildcard 0.0.0.7, Total IPs 8, and 6 Usable Hosts. Ideal for DMZ Public Server Sub-Block & BGP Peering (6 Hosts).
🛠️ Sibling Calculators in this Category:
Calculate IPv4 network address, broadcast, usable host range, netmask, wildcard, binary mask, and RFC address type (RFC 1918, /31, CGNAT).
Split an IPv4 network into N equal subnets or allocate boundary-aligned VLSM blocks by required host count with CSV and Markdown export.
Expand and compress IPv6 addresses per RFC 5952, calculate network prefix boundaries, /64 SLAAC subnet counts, and child prefix blocks.
Calculate Limit-At (CIR), Max-Limit (MIR), Burst, PCQ, and FQ-CoDel for RouterOS v7 with automated configuration script generation.
Engineering Sensitivity Analysis, Response Curve & Technical Citation
1. 1. 3-Point Engineering Sensitivity & Tolerance Envelope
Comparative evaluation across theoretical laboratory bounds (0% loss), current nominal operating point, and conservative field safety bounds (±15% thermal/aging derating).
| Evaluated Parameter | Ideal Theoretical Bound | Nominal Operating Point | Conservative Safety Bound (±15%) | Engineering Derating Rule |
|---|---|---|---|---|
| Point-to-Point Link Distance | 4.5 | 5 | 5.75 | Engineering Safety Margin (+15% Overhead) |
| Operating Radio Frequency | 5.22 | 5.8 | 6.67 | Engineering Safety Margin (+15% Overhead) |
| Radio Transmit Power (TX) | 21.6 | 24 | 27.6 | Engineering Safety Margin (+15% Overhead) |
| Antenna Gain (Dish / Sector) | 20.7 | 23 | 26.45 | Engineering Safety Margin (+15% Overhead) |
| Obstacle Height (Trees / Building) | 10.8 | 12 | 13.8 | Engineering Safety Margin (+15% Overhead) |
2. 2. Mathematical Function Curve & Operating Coordinate (x₀, y₀)
3. 3. Physical Constants & Normative Standard Clauses
DC Loop Resistance for 23 AWG Solid Copper Cat6
Clause 6.4.1 / Table 145-1 — Nominal 23 AWG solid copper loop resistance at 20°C is 14.0 Ω/100m (TIA maximum ceiling is 18.8 Ω/100m).
Single-Mode Optical Fiber Attenuation Coefficient at 1490 nm
Table 1 / Class B+ & C+ Optical Path — Typical G.652.D attenuation at 1490 nm downstream is 0.22–0.25 dB/km (1310 nm upstream: 0.35 dB/km).
Temperature Coefficient of Resistance for Copper
International Annealed Copper Standard — Used in thermal derating equation: R(T) = R_20 × [1 + 0.00393 × (T - 20)].
4. 4. Independent Technical & Academic Citation (IEEE / APA 7th / BibTeX / LaTeX)
Use the standard citation formats below to reference this computational methodology in engineering specifications, audit reports, or academic papers.
[IEEE] KalkuNet Engineering Team, "Wireless PtP Link Budget & Fresnel Zone Calculator — Standard Engineering Computational Instrument," KalkuNet Technical Suite, 2026. [Online]. Available: https://kalkunet.com/en/tools/wireless-ptp-calculator. [Accessed: 2026-11-08].
[APA 7th] KalkuNet Engineering Team. (2026). Wireless PtP Link Budget & Fresnel Zone Calculator (Production release 2026-11-08) [Engineering computational software]. KalkuNet. https://kalkunet.com/en/tools/wireless-ptp-calculator
@software{kalkunet_wireless_ptp_calculator_2026,
author = {{KalkuNet Engineering Team}},
title = {{Wireless PtP Link Budget & Fresnel Zone Calculator --- KalkuNet Engineering Suite}},
year = {2026},
publisher = {KalkuNet.com},
url = {https://kalkunet.com/en/tools/wireless-ptp-calculator},
urldate = {2026-11-08}
}
% LaTeX Engineering Derivation — Generated via https://kalkunet.com/en/tools/wireless-ptp-calculator
\begin{equation}
\text{Model: } FSPL (dB) = 20 × log10(Dist km) + 20 × log10(Freq GHz) + 92.45
\end{equation}
% Parameter Input Terukur: distKm = 5, \; freqGhz = 5.8, \; txDbm = 24, \; antGainDbi = 23
% Hasil Evaluasi Numerik : distKm = \mathbf{5}, \; freqGhz = \mathbf{5.8}, \; txDbm = \mathbf{24}