Logarithmic diagnostic tools for link budget range, power conversion, antenna elements, Fresnel zones, cable losses, and VSWR matches.
⚙ Link Presets
⚙ Link Parameters
Theoretical Max (0 dB margin)--km(-- mi)
Real-World Range (with Margin)--km(-- mi)
💡 Note: DJI firmware enforces hard distance caps: V1/Vista (13.3 km), O3 (20 km), O4 Pro (32 km).
Max Path Loss--dB
EIRP--dBm
EIRP (Watts)--W
System Gain--dB
📈 Received Power vs. Distance
⚙ Power Presets
🔄 Power Conversion Calculator
mW
dBm
W
Power Conversions Rules of Thumb: • +3 dB = Doubles milliwatt power output (e.g. 100mW ➔ 200mW is +3dB).
• +10 dB = 10x milliwatt power output (e.g. 100mW ➔ 1000mW is +10dB).
• -3 dB = Halves milliwatt power output.
• -10 dB = 1/10th milliwatt power output.
⚙ Quick Scenarios
🔄 dB Change
FPV Signal Variance Examples: • +3 dB: Doubling transmitter power (e.g. 400mW to 800mW).
• +6 dB: Upgrading standard 2dBi receiver omni to an 8dBi patch. This doubles the range!
• -6 dB: Flying behind dense foliage, or pointing antennas 90° out of polarization.
New Range--x
Change--
New Area--x
Change--
⭕ Coverage Area Circle Comparison
⚙ Antenna Presets
⚙ Antenna Parameters
Element Length--mm
Inches--in
Full Wavelength (λ)--mm
Monopole (Whip) Design
Total Length--mm
Active Element (1/4 λ)--mm
5/8 Wave Element--mm
Half-Wave Dipole Design
⚙ Frequency Presets
⚙ Path Parameters
Clearance profile: keep at least 60% of the first Fresnel zone radius free of obstructions (terrain, buildings, trees) to avoid thermal fade loss.
At Obstacle Radius--m
Max (at midpoint)--m
60% clear radius--m
Midpoint Bulge--m
Total Clearance Req.--m
Recommended height--m
🏔️ Path Fresnel Profile
⚙ Cable Presets
⚙ Cable Configuration
Total Loss--dB
Loss per meter--dB/m
Power Delivered--%
Effective Output--mW
Power in dBm--dBm
Wattage Lost--mW
📉 Cable Loss vs. Length
⚙ Match Presets
⚙ Impedance Matching
VSWR (Voltage Standing Wave Ratio): • 1.0:1: Perfect match (0% power reflected).
• ≤ 1.5:1: Excellent match (4% reflected).
• ≥ 2.0:1: High reflection. Ratios above 3.0:1 can damage the transmitter (VTx) from heat.
Reflected Power--%
Return Loss--dB
Refl. Coefficient (Γ)--
Power Delivered--%
Mismatch Loss--dB
📶 Power Splitting Gauge
Radio Frequency Calculators
📖 Overview
A comprehensive suite of RF diagnostic tools designed to analyze link budgets, estimate maximum range, convert dBm/mW units, design dipole antennas, calculate Fresnel clearance, measure coaxial cable attenuation, and evaluate VSWR impedance matching.
🛠️ How to Use
Max Range & Link Budget: Select a quick preset or adjust individual parameters to compute theoretical max range (0 dB margin) vs real-world range (with Fade Margin):
1.1 Frequency (MHz): Sets operational radio band (e.g. 5800 MHz, 2400 MHz, 915 MHz), where higher frequencies experience greater free-space path loss per kilometer.
1.2 TX Power (dBm / mW): Defines transmitter output power level (up to 10W / 40 dBm), increasing overall RF link budget.
1.3 TX Antenna Gain (dBi): Configures transmitter antenna gain, focusing radiated RF output energy (e.g. 2.0 dBi omni).
1.4 RX Antenna Gain (dBi): Configures receiver antenna gain to boost incoming signal reception (e.g. 8.0–14.0 dBi directional patch).
1.5 RX Sensitivity (dBm): Specifies receiver noise floor threshold required to maintain signal lock (e.g. -105 to -123 dBm for ELRS).
1.6 Fade Margin (dB): Adds safety headroom for obstacle absorption, quad orientation changes, and antenna nulls.
Power Converter (mW ⟷ dBm): Convert between milliwatts (mW) and decibel-milliwatts (dBm).
Times Further: Calculate range and coverage area multipliers when upgrading Tx power or antenna gain.
Antenna Designer: Compute quarter-wave/half-wave element lengths based on target frequency.
Mid-range directional video reception (~60° beamwidth)
7-Turn Helical / High-Gain Patch
12.0 - 14.0 dBi
Long-range video reception (~35° beamwidth)
12-Turn Helical / Antenna Array
15.0 - 16.5 dBi
Ultra long-range ground station / tracker (~20° narrow beam)
Yagi-Uda Array
11.0 - 14.0 dBi
High-gain directional control/video antenna
💡 Key Insights: Antenna Polarization & Gains
dBi vs dBiC:1 dBiC = 1 dBi. Gain rated in dBiC represents isotropic gain specifically for Circularly Polarized (CP) antennas. Enter dBiC ratings directly into antenna gain fields.
Linear ➔ Circular Mismatch: Pairing a Linearly Polarized antenna (e.g. whip on quad) with a Circularly Polarized antenna (e.g. patch on goggles) incurs an inherent 3 dB polarization mismatch loss (50% power drop).
Opposite Handedness Mismatch: Pairing opposite circular polarizations (e.g. RHCP ➔ LHCP) results in severe signal rejection (>20 dB loss).