This hub gathers the RF maths behind wireless links, antennas and radio coverage: converting power units, budgeting losses, sizing antennas and predicting how far a signal will reach. It's aimed at RF and network engineers, ham and two-way radio operators, WISP and microwave link planners, and students working through propagation problems.
Power, gain and unit conversions
Start here to get every value into consistent units before any link budget: convert dBm to watts for transmit power, translate antenna gain between dBi and dBd, and combine transmit power with gain into EIRP.
Feedline and antenna matching
Use these when the problem is at the radio and antenna end — cable loss over a run, how well the load is matched (VSWR), the physical or electrical length of a coax section, and cutting an antenna to frequency.
Path loss and propagation
Reach for these to estimate how much signal is lost between antennas: free-space loss for a clean line-of-sight budget, two-ray for ground-reflection at lower heights, Fresnel clearance to check obstructions, plus Doppler shift for moving transmitters.
Coverage and link viability
Once losses and gains are known, use these to decide whether a link actually closes: radio horizon and repeater radius for distance, link margin and thermal noise floor for the budget, and SNR for the receiver's usable signal.
Channel capacity and throughput
Use these when the question is data rate rather than reach: Shannon capacity for the theoretical ceiling from bandwidth and SNR, occupancy for fitting channels into a band, and transfer time for real file sizes.
