Ham Radio Tools
Practical calculators for antenna design, RF, propagation, feedline and field operation — built for radio amateurs who like to understand and build their stations.
Built for practical station work
Use these calculators as engineering starting points for antenna dimensions, RF power, transmission lines, propagation planning and portable operation. Calculated values should be checked against the actual installation, instrument readings and current regulatory requirements.
Start with the job
What are you trying to do?
Pick the task rather than hunting through a long calculator list. Each route leads to the tools normally used together during an antenna build, station check or operating session.
Browse by discipline
Propagation & Reference
DX planning, Maidenhead grids, propagation references and band information.
View toolsField Tools
Portable-station planning tools for power, battery use and practical setup decisions.
View toolsHF Propagation Snapshot
Solar indices and band conditions change throughout the day. This homepage does not pull live numbers (CORS limits from most public feeds). Use the dedicated page or the trusted external sources below for current data.
Cross-check at least two sources before a critical DX attempt. Propagation page also carries reference charts and planning notes.
Antenna Calculators Build & tune
Half-Wave Dipole
Classic 468/f formula with end-effect. Horizontal & multi-band notes.
Inverted-V Dipole
Single support, shortened for apex angle. Great for limited space.
Yagi-Uda
3–7 element basic design. Reflector, driven, directors + spacing.
End-Fed Half-Wave
EFHW length + harmonic coverage. Popular portable multi-band.
OCF Dipole
Off-center-fed multi-band dipole with feed-point split ratios.
Random Wire
Safe multi-band lengths that avoid high-impedance resonances.
Trap Dipole
Two-band trap dipole starting lengths and trap placement notes.
¼-Wave Vertical
Radiator + radial lengths. Ground-plane friendly.
⅝-Wave Vertical
Higher gain vertical with matching notes.
Coil-Loaded Vertical
Shortened mobile / portable vertical + loading inductance.
J-Pole / Slim Jim
VHF/UHF favorite. No radials required.
Delta Loop
Full-wave equilateral triangle. Low-angle DX performer.
Full-Wave Loop
Square / rectangular skyloop dimensions.
Moxon Rectangle
Compact 2-element beam with excellent F/B.
Magnetic Loop
Small transmitting loop – efficiency, Q, capacitor voltage.
Station & Path Tools Operate & measure
Grid Square & Bearing
Lat/Lon ↔ Maidenhead + distance & beam headings.
Coax Loss Calculator
Loss by cable type, length, frequency and SWR.
Antenna Trimmer
Current resonance → exact length to cut or add.
Balun / Unun
Turns ratios and common 1:1, 4:1, 9:1, 49:1 designs.
Coil / Toroid Winder
Air-core & ferrite turns for loading coils and chokes.
SWR ↔ Return Loss
Quick conversion between SWR, RL and reflection coeff.
RF Exposure
Simplified free-space RF power-density estimate; not a compliance determination.
Radio Horizon
VHF/UHF line-of-sight distance from antenna heights.
Unit Converter
Watts ↔ dBm, feet ↔ meters, dBd ↔ dBi and more.
Band Plan Quick Ref
Region 2 / US band segments and common modes.
Why these tools?
Each tool is designed around a real station task: start with a calculation, understand what the number means, then verify it against the physical installation or an instrument reading. The calculators run in your browser with no account required.
Data sources for propagation: NOAA SWPC & N0NBH/HamQSL public widgets. Always verify real-world performance with an antenna analyzer.