⚡ Industrial RF Microwave Sizing Engine
Wireless Bridge Link Budget & Fresnel Zone Sizing Calculator
Calculate free space path loss (FSPL), received signal strength indicator (RSSI), fade margin reliability, and 60% first Fresnel zone clearance height for 5.8GHz and 2.4GHz outdoor point-to-point (PTP) / point-to-multipoint (PTMP) wireless CCTV bridges.
RF Link Parameters & Antenna Sizing
km
dBm
dBi
dB
m
Cams
RF Sizing Calculations
● Optimal Link
Received Signal Strength (RSSI)
Target: ≥ -65 dBm
-56.7 dBm
Signal margin: 23.3 dB above minimum receiver threshold (-80 dBm).
Free Space Path Loss (FSPL)
EIRP: +46.0 dBm
107.7 dB
Microwave propagation attenuation at 1.0 km @ 5.8 GHz.
1st Fresnel Zone 60% Clearance Radius (r₁)
100% r₁ = 3.60 m
2.16 m
Keep minimum 2.16 m radial clearance from all midpoint obstacles.
Recommended Pole Height (AGL)
Earth Curvature: 0.02 m
5.2 m (17.1 ft)
Elevation above ground level to guarantee 60% Fresnel clearance over 3.0 m obstacle.
Real-World Usable Throughput
CCTV Load: 24.0 Mbps
150+ Mbps
Supports up to 25x 4MP streams simultaneously with 84% headroom.
Direct Answer & Engineering Math Principles
Verified microwave RF physics models used by Fengtaida field telecommunications engineers.
Direct Answer: How is Microwave Wireless Bridge Link Budget & Clearance Sized?
A reliable industrial wireless video surveillance link requires two mandatory conditions: (1) Adequate Received Signal Strength (RSSI between -50 dBm and -65 dBm) with at least 15 dB fade margin above the receiver threshold, and (2) A minimum of 60% clearance of the 1st Fresnel zone across the entire line of sight (LOS). Path loss is calculated via the Free Space Path Loss (FSPL) equation, while antenna pole elevation must account for midpoint terrain, vegetation, and earth curvature.
1. Free Space Path Loss (FSPL)
FSPL(dB) = 20·log₁₀(d) + 20·log₁₀(f) + 32.44
Where d is distance in kilometers and f is carrier frequency in MHz. Quantifies electromagnetic dispersion across open space.
2. Received Signal Power (RSSI)
RSSI = P_tx + G_tx + G_rx - FSPL - L_cable
Where P_tx is transmitter power (dBm), G is antenna gain (dBi), and L_cable accounts for RF connector insertion loss.
3. 1st Fresnel Zone Radius (r₁)
r₁(m) = 8.656 · √( d_km / f_GHz )
Midpoint ellipsoid radius. Industrial microwave engineering requires at least 60% of r₁ free of any physical obstruction to prevent multi-path phase cancellation.
4. Minimum Pole Elevation (AGL)
H_pole = H_obstacle + 0.6·r₁ + (d² / 51)
Height Above Ground Level ensuring line-of-sight elevation over midpoint obstacles, including earth curvature sag for links exceeding 5 km.
4-Step RF Wireless Link Deployment Workflow
Standard operating procedure for telecommunications integrators and remote perimeter security.
STEP 01
Optical Line-of-Sight & GPS Survey
Verify direct visual optical line of sight using binoculars or drone elevation. Log exact GPS coordinates and elevation profiles for master and slave nodes.
STEP 02
Link Budget & Fade Margin Calculation
Compute RSSI to ensure target signal strength (-55 to -65 dBm) with at least 15 dB fade margin to withstand torrential rain, fog, and seasonal foliage growth.
STEP 03
Pole Height & Fresnel Clearance Verification
Erect mounting masts with rigid guy wires to position antenna phase centers above the 60% Fresnel clearance envelope, eliminating multipath reflections.
STEP 04
Precision Beam Alignment & Bitrate Locking
Perform fine azimuth and elevation adjustments using built-in RSSI signal alignment LEDs or Web UI signal meters. Lock modulation rate and verify ping jitter < 3ms.
Wireless Bridge Performance Matrix by Distance & Frequency
Factory field test benchmarks for Fengtaida industrial microwave wireless bridge series.
| Link Distance | Recommended Band | Antenna Type | Expected RSSI | 60% Fresnel Clearance | Usable Bandwidth | Max 4MP Stream Qty |
|---|---|---|---|---|---|---|
| 1.0 km (Short) | 5.8 GHz ISM | 14–19 dBi Integrated Panel | -54 dBm (Optimal) | 2.16 m | 150–200 Mbps | Up to 25 Streams |
| 3.0 km (Medium) | 5.8 GHz ISM | 19 dBi Directional Panel | -62 dBm (Optimal) | 3.74 m | 120–160 Mbps | Up to 20 Streams |
| 5.0 km (Long) | 5.8 GHz ISM | 23 dBi High-Gain Panel | -61 dBm (Optimal) | 4.82 m | 90–130 Mbps | Up to 15 Streams |
| 10.0 km (Perimeter) | 5.8 GHz ISM | 27 dBi Parabolic Dish | -63 dBm (Optimal) | 6.82 m | 60–100 Mbps | Up to 10 Streams |
| 15.0 km (Harbor/Mine) | 5.8 GHz ISM | 30 dBi Parabolic Dish | -65 dBm (Good) | 8.35 m | 40–70 Mbps | Up to 8 Streams |
| 20.0 km (Extreme) | 5.8 GHz / 4.9 GHz | 32 dBi Grid Parabolic Dish | -67 dBm (Good) | 9.65 m | 30–50 Mbps | Up to 5 Streams |
Engineering FAQ: Microwave Link Budget & Fresnel Clearance
Practical design questions answered by Fengtaida telecommunications and video surveillance engineers.
What is the ideal RSSI signal range for reliable CCTV video streaming?
For mission-critical video surveillance, the target RSSI should be between -50 dBm and -65 dBm. If the signal is hotter than -45 dBm, the receiver front-end can saturate, causing packet loss. If the signal drops below -72 dBm, modulation rates drop, introducing packet dropouts, video pixelation, and PTZ telemetry lag during rain or fog.
Why is 60% Fresnel zone clearance required instead of just visual line of sight?
Microwave radio waves expand as an elliptical volume between the transmitter and receiver. If physical obstacles (such as tree tops, building parapets, or terrain ridges) penetrate into the inner 60% boundary of the 1st Fresnel zone, electromagnetic waves reflect off the obstruction and arrive out-of-phase at the receiving antenna, causing destructive interference and severe signal degradation even if optical sight is unobstructed.
When should I choose 5.8 GHz versus 2.4 GHz for wireless video transmission?
5.8 GHz is recommended for 95% of industrial video surveillance applications because it offers wider channel bandwidth (20/40/80 MHz), higher aggregate throughput (up to 300+ Mbps), smaller Fresnel zone clearance requirements, and significantly less background RF interference. 2.4 GHz is only used when slight foliage penetration is unavoidable over short distances (< 1 km) where lower bandwidth is acceptable.
How does earth curvature affect long-distance wireless bridge links (> 5 km)?
The curvature of the Earth creates an apparent "bulge" at the midpoint between two distant poles. At 10 km, the earth bulge is approximately 1.96 meters; at 20 km, it reaches 7.84 meters. For links exceeding 5 km, pole height calculations must add this earth curvature allowance to the 60% Fresnel radius plus obstacle height to prevent ground reflection loss.
Can Fengtaida wireless bridges be powered directly from solar DC battery banks?
Yes. All Fengtaida industrial wireless bridges support standard 24V Passive PoE or 48V IEEE 802.3af/at PoE, and feature internal wide-voltage DC step-down converters (12V–36V DC). They can be directly connected to Fengtaida off-grid solar LiFePO4 battery power cabinets without requiring power inverters.
Matched Fengtaida Industrial Wireless Bridge Hardware
Ruggedized IP67 outdoor point-to-point and point-to-multipoint microwave transmission equipment.
1–5 km Point-to-Point
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WB58-19P Industrial 5.8GHz Wireless Bridge
Integrated 19 dBi dual-polarized directional panel antenna, 27 dBm high-power radio, IP67 weatherproof enclosure, 300 Mbps PHY throughput.
- Frequency: 5.180–5.825 GHz
- Antenna: 19 dBi Integrated
- Tx Power: 27 dBm (500 mW)
- Enclosure: IP67 / -40°C~+70°C
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WB58-27D Parabolic Dish Wireless Bridge
High-gain 27 dBi narrow-beam parabolic dish antenna for long-range perimeter, border security, harbor, and remote mining video backhaul.
- Frequency: 5.180–5.825 GHz
- Antenna: 27 dBi Dish
- Tx Power: 29 dBm (800 mW)
- Wind Survival: 200 km/h (125 mph)
Multipoint Base Station
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BS58-120S 5.8GHz Sector Base Station
120° sector base station designed to aggregate up to 16 remote slave camera stations into a centralized NVR / VMS control center.
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- Beamwidth: 120° Azimuth
- Clients: Up to 16 Nodes
- Protection: 6kV Surge / IP67