Ham Radio VHF & Satellite Calculators
Nine VHF and satellite calculators for amateur radio: radio horizon, Yagi stacking, Doppler shift, dish gain, free-space path loss, satellite footprint, EME link budget, noise cascade, and mast-head preamp comparison.
Radio Horizon Distance Calculator
Maximum line-of-sight distance between two stations given antenna heights. Uses the standard 4/3 Earth radius correction for VHF/UHF propagation.
Yagi Stacking Distance and Gain Calculator
Optimum stacking distance for two or four identical Yagis, combined gain, and power splitter requirements.
Satellite Doppler Shift Calculator
Uplink and downlink Doppler shift at any satellite elevation angle. Shows AOS, TCA, and LOS frequency offsets for tuning compensation.
Parabolic Dish Gain and Beamwidth Calculator
Gain, half-power beamwidth, and feed dimensions for a parabolic dish at any frequency and dish diameter.
Free-Space Path Loss Calculator (VHF/UHF/Microwave)
FSPL at VHF, UHF, and microwave frequencies. Includes a table at common amateur radio satellite frequencies.
Satellite Footprint and Coverage Calculator
Ground footprint radius, coverage area, and minimum elevation angle for any orbital altitude.
Earth-Moon-Earth (EME) Link Budget Calculator
Complete EME link budget including free-space path loss to the Moon, antenna gain requirements, and minimum detectable signal for CW, JT65, and Q65 modes.
Cascaded Noise Figure Calculator (Friis Formula)
System noise figure for a receive chain: feedline, preamp, and receiver. Shows the importance of a low-noise mast-head preamp.
Mast-Head Preamp vs. Shack Preamp Comparison
System noise figure improvement from moving a preamp from the shack to the mast head (before the feedline loss).