Quality factor

In this equation, Tr is the 10-90% rise time of the signal . The 10-90% rise time is the time interval it takes the signal to go from 10% of its final value to 90% of its final value. For example, if a signal has a rise time of 0.5 ns, its bandwidth will be 700 MHz.

Antenna RF bandwidth is sometimes defined as the width in frequency at a level of 6 dB below the peak , which may include a minor lobe which exceeds the -6 dB level. Bandwidth is also a measure of frequencies over which an antenna can receive or radiate electromagnetic energy.