#antenna

VSWR and RF impedance-matching maths as an API, computed locally and deterministically. The vswr endpoint computes the voltage standing-wave ratio and its companion figures — the reflection coefficient Γ = (ZL − Z0)/(ZL + Z0) = √(Pr/Pf), the VSWR = (1+|Γ|)/(1−|Γ|), the return loss −20·log₁₀|Γ| dB, the mismatch loss and the percentage of power reflected and transmitted — from a reflection coefficient, a load and source impedance (Z0 default 50 Ω), or the forward and reflected power. The fromvswr endpoint goes the other way, deriving Γ, return loss and the power split from a VSWR figure. The power endpoint computes the reflected and transmitted power from a forward power and a VSWR or reflection coefficient. Everything is computed locally and deterministically, so it is instant and private. Ideal for RF, antenna, amateur-radio and wireless app developers, antenna-tuning and feedline tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is RF impedance match; for antenna gain and aperture use an antenna API.

api.oanor.com/vswr-api

Antenna length maths as an API, computed locally and deterministically. The dipole endpoint gives the total and per-leg length of a half-wave dipole for a frequency, in metres, feet, inches and centimetres, applying a velocity factor (about 0.95 for wire) and also reporting the classic 468 ÷ f(MHz) feet rule of thumb. The quarterwave endpoint gives the element length of a quarter-wave vertical or monopole, with the 234 ÷ f(MHz) rule. The element endpoint computes the length of an element at any fraction of a wavelength — full-wave, half-wave, quarter-wave, fifth-wave, five-eighths or a custom fraction. Frequencies accept Hz, kHz, MHz and GHz, and the velocity factor is configurable. Everything is computed locally and deterministically, so it is instant and private. These are starting lengths: real antennas need trimming and tuning for the lowest SWR, as end effects and surroundings shift the resonant length. Ideal for amateur-radio and RF tools, antenna and IoT design, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is antenna geometry; for general wavelength, frequency and photon energy use a wavelength API.

api.oanor.com/antenna-api