#rf

Transmission-line RF maths as an API, computed locally and deterministically for a lossless line. The input-impedance endpoint transforms a complex load impedance along a line, Zin = Z0·(ZL + jZ0·tanβl)/(Z0 + jZL·tanβl), from the characteristic impedance, the load resistance and reactance and the electrical length in degrees — a quarter-wave (90°) line inverts the load to Z0²/ZL while a half-wave (180°) line repeats it, which is the basis of impedance matching. The quarter-wave endpoint computes the characteristic impedance Z0 = √(Z1·Z2) of a quarter-wave transformer that matches two real impedances, exact at one frequency. The electrical-length endpoint converts a physical line length to its electrical length in wavelengths, degrees and radians at a frequency, using the on-line wavelength λ = vf·c/f with a velocity factor for the dielectric. Impedances are in ohms (the load split into resistance and reactance), electrical length in degrees, physical length in metres and frequency in hertz. Everything is computed locally and deterministically, so it is instant and private. Ideal for RF, antenna-matching, PCB, radar and microwave app developers, stub-matching and transformer-design tools, and electromagnetics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is line impedance transformation; for SWR and return loss use a VSWR API and for microstrip trace geometry a PCB API.

api.oanor.com/transmissionline-api

Rectangular-waveguide microwave maths as an API, computed locally and deterministically. The cutoff endpoint computes the cutoff frequency fc = (c/2)·√((m/a)²+(n/b)²) and cutoff wavelength of any TEmn or TMmn mode of a rectangular waveguide of inner width a and height b — below the cutoff a mode is evanescent and cannot propagate, and for the usual a > b the dominant mode is TE10 with fc = c/(2a). The guide-wavelength endpoint computes, at an operating frequency, the free-space wavelength, the guide wavelength λg = λ0/√(1−(fc/f)²) which is longer than free space, and the phase velocity (greater than c) and group velocity (the energy speed, below c). The modes endpoint lists every mode that propagates at a given frequency, sorted by cutoff, and identifies the dominant mode — so single-mode operation needs the frequency between the first and second cutoffs. Dimensions are in millimetres and frequencies in gigahertz, with c = 299,792,458 m/s. Everything is computed locally and deterministically, so it is instant and private. Ideal for RF, microwave, radar, satellite and antenna-feed app developers, waveguide-band and component-design tools, and electromagnetics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is metallic rectangular waveguide; for optical-fibre guiding use a fibre API and for SWR a VSWR API.

api.oanor.com/waveguide-api

Fresnel-zone and line-of-sight clearance maths for radio-link planning as an API, computed locally and deterministically. The radius endpoint computes the Fresnel-zone radius at any point along a path, rₙ = √(n·λ·d1·d2/(d1+d2)) with λ = c/f, together with the wavelength and the 60 % clearance that a near-free-space link needs. The midpoint endpoint gives the widest radius — the zone is fattest at the path midpoint — and its 60 % clearance, the figure you size antenna heights against. The earthbulge endpoint adds the earth-curvature bulge, h = d1·d2/(12.75·k) with k ≈ 4/3 for a standard atmosphere, and combines it with the Fresnel clearance into a total obstruction clearance for the path. Distances are in kilometres, frequency in gigahertz, radii in metres. Everything is computed locally and deterministically, so it is instant and private. Ideal for wireless, WISP, microwave-backhaul, LoRa and amateur-radio app developers, link-planning and coverage tools, and RF engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is Fresnel-zone & line-of-sight clearance; for free-space path loss and link budget use a path-loss API and for antenna gain use an antenna API.

api.oanor.com/fresnel-api

RF path-loss and link-budget maths as an API, computed locally and deterministically. The fspl endpoint computes the free-space path loss, FSPL(dB) = 20·log₁₀(d_km) + 20·log₁₀(f_MHz) + 32.44, the ideal line-of-sight attenuation between two antennas, and the wavelength. The linkbudget endpoint computes the received power, Prx = Ptx + Gtx + Grx − path loss − cable losses, the EIRP, and — given a receiver sensitivity — the link margin and whether the link closes. The dbm endpoint converts RF power between dBm, watts and dBW (0 dBm = 1 mW, 30 dBm = 1 W). Everything is computed locally and deterministically, so it is instant and private. Ideal for wireless, IoT, LoRa, Wi-Fi and radio app developers, link-planning and coverage tools, and RF engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is RF link budget; for VSWR and impedance match use a VSWR API and for antenna gain use an antenna API.

api.oanor.com/pathloss-api

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