Ham Radio Transmission Line Calculators
Eleven transmission line calculators covering coaxial cable loss, SWR and return loss, velocity factor, quarter-wave transformers, stub matching, TDR fault location, and impedance transformation. All run entirely in your browser.
Coax Matched-Line Loss Calculator
Insertion loss for common coaxial cables at any frequency and length. Shows power delivered to antenna and equivalent transmitter power at the shack.
Additional Feedline Loss Due to SWR
Calculates the extra insertion loss caused by operating a coaxial cable with mismatched SWR compared to operating at matched (1:1) conditions.
SWR ↔ Return Loss ↔ Reflection Coefficient
Convert between any combination of SWR, return loss (dB), and reflection coefficient magnitude |Γ|. Also shows mismatch loss.
λ/4 Coax Impedance Transformer
Calculates the required coax characteristic impedance and physical length for a quarter-wave impedance transformer between two resistive impedances.
Electrical Length and Physical Length Converter
Converts between physical cable length and electrical length (in degrees or wavelengths) at any frequency and velocity factor.
Shunt Stub Matching Calculator
Calculates the distance from antenna to stub and stub length for a single-stub shunt match to 50 Ω. Works with open or shorted stubs.
Load Impedance Through a Transmission Line
Calculates the impedance seen at the shack end of a coaxial feedline given the antenna's actual feed point impedance. Replicates what a NanoVNA would read at the shack.
TDR Fault Distance Calculator
Converts NanoVNA TDR round-trip time to physical distance along coaxial cable. Includes VF calibration from known cable length.
Coax DC Loop Resistance (Far End Shorted)
Expected DC resistance for a good coaxial cable with the far end shorted. Used to verify cable continuity and detect high-resistance faults.
Coax Z0 from Physical Dimensions
Calculates the characteristic impedance of a coaxial cable from inner conductor diameter, outer conductor inner diameter, and dielectric constant.
Ferrite Coax Choke Minimum Turns Calculator
Calculates the number of turns required on a ferrite toroid to achieve a specified choking impedance at a given frequency for a 1:1 current balun.