Methodology

How the calculators work, where the data comes from, and what the limitations are.

Antenna calculations

Dipole, J-pole, ground plane, and Yagi dimensions use standard textbook formulas from the ARRL Antenna Book and Kraus's Antennas. The dipole formula (468/f) includes the standard 5% end-effect correction. Yagi element dimensions are based on NBS and DL6WU optimized designs. All lengths are starting points; real antennas need trimming to account for element diameter, mounting effects, and nearby conductors.

Propagation estimates

Radio horizon uses the 4/3 Earth radius model for standard atmospheric refraction. Repeater and simplex range estimates apply terrain reduction factors to the line-of-sight distance. These are planning numbers, not predictions. Real coverage depends on terrain features that a browser can't model.

Coax loss data

Loss values are manufacturer specifications at standard test frequencies. Interpolation between data points uses a square-root-of-frequency relationship, which matches how skin-effect loss scales. Real cable loss increases with age, moisture intrusion, UV exposure, and connector quality.

RF exposure

MPE calculations follow FCC OET Bulletin 65 using the far-field power density formula. Near-field exposure (within a few wavelengths of the antenna) is more complex and not modeled here. The calculator is conservative: it assumes a worst-case main-lobe exposure.

Equipment data

Specifications and keying figures are compiled from manufacturer documentation — manuals, brochures, spec sheets — alongside published independent reviews, technical articles, and regulatory filings such as FCC certification records. Where possible, claims are cross-checked against independent sources; where only the manufacturer's word exists, the page says so. Short quotations are attributed to their source. We don't republish other publications' content, we don't use marketplace listing data, and figures nobody has independently verified are labeled unverified rather than presented as fact. Spotted an error? support@keyandcarrier.com.

Regulatory data

Band allocations, power limits, and license classes are sourced from each country's published regulations. US data from FCC Part 97 and Part 95. UK data from Ofcom's amateur radio licence terms. Canadian data from ISED RBR-4. Australian data from ACMA's amateur licence conditions. Data is reviewed periodically but regulations change; always verify against the current official source for your country.

Link budget

Free-space path loss uses the standard formula: FSPL = 20·log₁₀(d) + 20·log₁₀(f) + 32.44 (distance in km, frequency in MHz). This assumes an unobstructed path. Real-world links have additional losses from foliage, buildings, terrain diffraction, and atmospheric absorption that this calculator does not model.