Tool collection
RF & Tools
Practical tools for RF power, SWR, transmission lines, impedance and matching.
A connected RF troubleshooting workflow
RF work becomes easier when power, impedance, transmission-line loss and matching are treated as connected quantities rather than isolated numbers. These tools cover common calculations for amateur-radio stations, from SWR and return loss through coaxial loss, 50-ohm voltage/current relationships, EIRP/ERP, link budgets and transmission-line behaviour. Use the results to estimate what a system should do, then compare them with measurements from an analyser, wattmeter or other suitable instrument. Cable type and length matter, and so do connector losses, mismatch and frequency. A calculator can show the expected trend without knowing every detail of a real installation. For station design, work from the transmitter output through the feedline and matching network to the antenna, keeping units consistent at every step. The related tools are intentionally linked so that a result from one calculation can lead naturally to the next engineering question.
Tools in this collection
Swr Rl
Convert between SWR, Return Loss (dB) and reflection coefficient.
Coax Loss
Estimate coaxial cable loss by type, length, frequency and SWR. Uses typical reference attenuation values and a simplified mismatch-loss model.
Rf 50Ohm
Calculate RF power, RMS/peak voltage, current and resistance for a resistive load.
Eirp Erp
Calculate effective radiated power from transmitter power, feedline loss, antenna gain and efficiency.
Transmission Line
Transform a complex load impedance through a lossless transmission line and estimate electrical length and matched cable loss.
Efhw Transformer
Estimate impedance ratio and transformer turns ratio for an end-fed half-wave transformer.
Link Budget
Calculate free-space path loss, received power and link margin from distance, frequency, antenna gains and losses.
Smith Chart
Plot a complex load impedance on a Smith chart and calculate normalized impedance, reflection coefficient, SWR and return loss.
Unit Converter
Convert watts ↔ dBm ↔ dBW, metres ↔ feet, dBi ↔ dBd. One-way conversion design to avoid conflicting inputs.
Antenna Trimmer
Calculate how much to cut or lengthen an antenna to move resonance to the desired frequency.
Rf Exposure
Free-space power-density estimate only. Not a full regulatory compliance calculator. Does not account for near-field, ground reflection, antenna pattern or jurisdiction-specific limits.
Balun
Complete guide to ham radio baluns and ununs: 1:1 current balun, 4:1 for OCF dipoles, 9:1 for random wires, 49:1 for EFHW. Learn ratios, core choices, winding tips and common mistakes.
A connected RF workflow
RF calculations become much more useful when the results are considered as parts of one signal path. Start with transmitter power, then account for feedline loss, connector loss and any matching network before considering antenna gain and effective radiated power. If a measured SWR is high, convert it to return loss when comparing equipment specifications, then use impedance or transmission-line tools to understand what the load may look like at another reference plane. Cable loss is frequency dependent, and a tuner can improve the transmitter-side match without removing loss already present in the feedline. These distinctions prevent common troubleshooting mistakes. The tools are intended to answer one question at a time, but their related links make it easy to move from power to loss, impedance and matching. For a real station, use the calculator for the expected value and an appropriate meter or analyser for the measured value; differences between the two are often the clue that identifies the installation detail that needs attention.
When a calculation is used for troubleshooting, change one assumption at a time. That makes it easier to identify whether the difference comes from cable loss, mismatch, antenna gain, power measurement or an instrument reference plane rather than from the formula itself.