📖 How to Use
🎯 Getting Started
This tool helps you design wireless links by calculating maximum range and visualizing antenna patterns:
- Range Calculator: Estimate maximum link distance using the Friis Transmission Equation
- Antenna Visualizer: Compare directional vs omnidirectional antenna radiation patterns
- Connector Guide: Identify common RF connectors for your transmission media
📐 Friis Transmission Equation
The fundamental equation for calculating free-space path loss:
PR = PT + GT + GR - Lpath (in dBm)
- PR: Received power at the receiver (dBm)
- PT: Transmit power (dBm)
- GT: Transmit antenna gain (dBi)
- GR: Receive antenna gain (dBi)
- Lpath: Free-space path loss = 20·log₁₀(d) + 20·log₁₀(f) + 32.45 dB
💡 Range depends on receiver sensitivity - typical values: -70 dBm (Wi-Fi), -100 dBm (LoRa), -120 dBm (GPS)
📊 Antenna Gain & Beamwidth
Higher gain antennas focus energy in specific directions, increasing range but reducing coverage angle:
- Omnidirectional: 0-3 dBi gain, 360° horizontal coverage (dipoles, whips)
- Directional: 6-24+ dBi gain, narrow beamwidth (Yagi, patch, parabolic dish)
- Beamwidth: Angle where power drops to half (-3 dB). Higher gain = narrower beam
Trade-off: Directional antennas increase range but require precise alignment
🔌 RF Connectors
Selecting the right connector ensures signal integrity and proper media matching:
- SMA: Compact, threaded, up to 18 GHz (Wi-Fi, GPS modules, SDR)
- RP-SMA: Reverse-polarity SMA (common on consumer Wi-Fi devices due to FCC regulations)
- N-Type: Weatherproof, threaded, up to 11 GHz (outdoor antennas, base stations)
- BNC: Bayonet mount, up to 4 GHz (test equipment, video, older RF gear)
- U.FL/IPEX: Miniature, fragile, up to 6 GHz (embedded systems, PCB connections)
⚠️ Connector gender and polarity matter - verify compatibility before ordering hardware
🌍 Real-World Factors
The Friis equation assumes free-space (line-of-sight). Real-world links experience additional losses:
- Obstructions: Buildings, trees, terrain (add 10-30 dB loss)
- Multipath: Reflections causing signal cancellation (urban/indoor environments)
- Atmospheric: Rain fade (especially above 10 GHz), fog, humidity
- Cable Loss: Coax attenuation (use shortest possible cables, high-quality media)
Design Margin: Add 10-20 dB safety margin for reliable links in non-ideal conditions
📱 Common Applications
- Wi-Fi (2.4/5 GHz): 100-300m outdoor with directional antennas
- LoRa (868/915 MHz): 2-15 km depending on spreading factor and environment
- Cellular (700-2600 MHz): Several kilometers with base station antennas
- Point-to-Point Microwave (5-60 GHz): 50+ km with high-gain dishes
📡 Link Budget Calculator
Calculate maximum wireless range using the Friis Transmission Equation
📊 Antenna Beamwidth Visualizer
Compare directional vs omnidirectional antenna radiation patterns
Top View (Azimuth)
Side View (Elevation)
🎯 Gain vs Coverage Trade-off
Omnidirectional antenna radiates equally in all directions. Good for mobile devices and wide-area coverage.
🔌 RF Connector Reference Guide
Identify common RF connectors for selecting proper transmission media hardware
SMA (SubMiniature A)
Frequency: DC - 18 GHz
Impedance: 50Ω
Mount: Threaded (hex nut)
Size: ~6.35mm outer diameter
Applications: Wi-Fi, GPS, SDR, test equipment, RF modules
Variants: SMA, RP-SMA (reverse polarity)
N-Type
Frequency: DC - 11 GHz
Impedance: 50Ω
Mount: Threaded (large hex nut)
Size: ~20mm outer diameter
Applications: Outdoor antennas, base stations, high-power RF
Features: Weatherproof, rugged, low loss
BNC (Bayonet Neill-Concelman)
Frequency: DC - 4 GHz
Impedance: 50Ω (75Ω variants exist)
Mount: Bayonet (quarter-turn lock)
Size: ~10mm outer diameter
Applications: Test equipment, oscilloscopes, video, older RF gear
Features: Quick connect/disconnect
U.FL / IPEX / MHF
Frequency: DC - 6 GHz
Impedance: 50Ω
Mount: Snap-on (friction fit)
Size: ~2.5mm outer diameter
Applications: Embedded systems, PCB connections, IoT devices
Features: Ultra-compact, low profile
MCX (Micro Coaxial)
Frequency: DC - 6 GHz
Impedance: 50Ω (75Ω available)
Mount: Snap-on (push-pull)
Size: ~4mm outer diameter
Applications: GPS receivers, mobile communications, compact RF modules
Features: Small, good for high-density boards
RP-SMA (Reverse Polarity)
Frequency: DC - 18 GHz
Impedance: 50Ω
Mount: Threaded (hex nut)
Size: Same as SMA (~6.35mm)
Applications: Consumer Wi-Fi routers, access points, IoT devices
Features: Gender/pin reversed from standard SMA
🎯 How to Choose the Right Connector
Higher frequencies require better quality connectors. Use SMA/N-type above 2 GHz, avoid BNC above 4 GHz.
Outdoor installations need weatherproof connectors (N-type best). Indoor/PCB use U.FL or SMA.
High-power transmitters require robust connectors (N-type best). Low-power IoT can use U.FL/MCX.
Embedded systems with limited space: U.FL (smallest) → MCX → SMA → N-type (largest).
Frequent connect/disconnect: BNC or SMA (500+ cycles). Permanent: U.FL acceptable (30 cycles).
Match connector impedance (50Ω or 75Ω) to your cable. Most RF systems use 50Ω, video uses 75Ω.