Attenuator calculator
Online calculator for Pi, T, bridged-T and L-pad attenuators: exact values, the nearest E24, the power split across the resistors and the minimum attenuation.
Directional coupler calculator
Online directional coupler and SWR meter calculator: insertion loss, the SWR measurement error caused by finite directivity, and a table of readings.
Wavelength calculator
Online wavelength calculator β frequency to wavelength and back, for any band.