radio tuning circuit

To have good reception, the "bandwidth" of the tunning circuit (the LC circuit) must be narrow, so that only the radio-frequency signal emitted by the radio station of interest is at resonance. A wide bandwidth enables signals of nearby frequencies from other stations also be received, thus causing interference.

The bandwidth (BW), which is the range of frequencies to be received by the tunning circuit, is given by
BW = R/(2.pi.L)
where R is the resistance of the circuit, and L is the inductance of the inductor.

In order to have a narrow bandwidth (i.e. a small value for BW), it is apparent from the equation that the circuit should have large value of L.

You may refer to the following web-page, bandwidth is explained under the section: Derived Parameters.

http://en.wikiversity.org/wiki/RLC_circuit