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API · /transmissionline-api

Transmission Line API

healthy 3,598 Subscribers

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.

#transmission-line #rf #impedance-matching #quarter-wave #microwave #developer-tools
api.oanor.com/transmissionline-api
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Machine-readable spec so AI agents can integrate this API.

/api/transmissionline-api/openapi.json
/api/transmissionline-api/llms.txt

Discovery: GET /api/index.json lists every API.

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
95 ms
Server probes · 24h
Subscribers
3,598
active
Total calls
20
last 7 days
status Full status page → · 24 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 2,450 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 2,450 calls/month
  • 2 req/sec
  • Input impedance + transformer + length
  • No credit card
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Starter

€10.00 /month

  • 40,500 calls / month
  • 6 requests / second
  • Hard cap (429 above quota, no overage)
  • 40,500 calls/month
  • 6 req/sec
  • Complex loads, velocity factor
  • Email support
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Pro

€26.00 /month

  • 258,000 calls / month
  • 15 requests / second
  • Hard cap (429 above quota, no overage)
  • 258,000 calls/month
  • 15 req/sec
  • Antenna-matching & transformer pipelines
  • Priority support
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Mega

€81.00 /month

  • 1,710,000 calls / month
  • 40 requests / second
  • Hard cap (429 above quota, no overage)
  • 1,710,000 calls/month
  • 40 req/sec
  • Platform scale
  • Dedicated SLA
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Related APIs

Other APIs with overlapping tags.

Waveguide 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 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 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 & Impedance Match 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

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Transmission Line API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Transmission Line API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Transmission Line API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Transmission Line API cost?
Transmission Line API has a free tier with 100 calls / month. Paid plans start at €10.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Transmission Line API GDPR-compliant?
All requests to Transmission Line API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/transmissionline-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/transmissionline-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/transmissionline-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/transmissionline-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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