[1] The theorem was developed in several papers between 1948 and 1960 by Lan Jen Chu,[2] Harold Wheeler,[3] and later by Roger F.
In practice this means that there is a limit to the bandwidth of data that can be sent to and received from small antennas such as are used in mobile phones.
A circular polarized antenna can be half the size[5] (an extension of the theory of Chu by Harrington).
For users this decreases the bitrate, limits range, and shortens battery life.
An equivalent circuit is a ladder line with the shunts (rungs) being inductors and the capacitors running in series (railings).
[7] In practice an electrically small antenna is one that is operated at a frequency below its natural resonance.
The addition of this extra component creates a tuned circuit, with a Q-factor that potentially limits the instantaneous bandwidth available for signals passing through the antenna.
This is a fundamental limit that sets a minimum size for any antenna used at a given frequency and with a given required bandwidth.
[9] The Chu limit gives the minimum Q, and by implication the maximum bandwidth, for an antenna of a given size on the assumption that it is lossless.