## Antenna systems::Bandwidth (signal processing)

### ::concepts

Filter::maximum Signal::range Which::passband Example::channel Spectral::width Where::value**Antenna systems**

In the field of antennas, two different methods of expressing relative bandwidth are used for narrowband and wideband antennas.<ref>{{#invoke:citation/CS1|citation |CitationClass=book }}</ref> For either, a set of criteria is established to define the extents of the bandwidth, such as input impedance, pattern, or polarization.

*Percent bandwidth*, usually used for narrowband antennas, is used defined as <math>\%B=100 \times \frac{f_H-f_L}{f_c}=200 \times \frac{f_H-f_L}{f_H+f_L} </math>. The theoretical limit to percent bandwidth is 200%, which occurs for <math>f_L = 0</math>.

*Fractional bandwidth or Ratio bandwidth*, usually used for wideband antennas, is defined as <math>B = f_H/f_L,</math> and is typically presented in the form of <math>B:1</math>. Fractional bandwidth is used for wideband antennas because of the compression of the percent bandwidth that occurs mathematically with percent bandwidths above 100%, which corresponds to a fractional bandwidth of 3:1.

If <math> \%B =200 \times \frac{f_H-f_L}{f_H+f_L} = p </math>

then <math> B = \frac{200+p}{200-p} </math>.

**Bandwidth (signal processing) sections**

Intro Overview X-dB bandwidth Antenna systems Photonics See also Notes References

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