A collection of useful online tools for the amateur radio experimenter

An excellent LC design tool for low-pass, high-pass & band-pass filters up to 20th order, using Chebyshev,  Elliptic, Butterworth, Inverse Chebyshev, Bessel & Legendre syntheses.

This calculator is useful when making antenna matching units, low pass filters, crystal sets, antenna traps, resonant circuits or anywhere where an air cored single layer inductor is required.

This calculator calculates the noise RMS Voltage for a circuit element for a given bandwidth, resistance and temperature.

A calculator designed to compute the VSWR, reflection coefficient, return loss and matching loss in a transmission line

This table shows the relationship between Power in [dBm] or [Watts] and Voltage in RMS, peak, peak-to-peak for sinusoidal signals in 50-Ohm systems.

An online Smith Chart analysis tool with frequency sweeps and bode plots

Microstrip design tool

FCC adopted limits for evaluating exposure from mobile and portable devices, such as cellular telephones and personal communications devices.