Editing Resonator (section)

===Loop-gap resonator===
{{main|loop-gap resonator}}
The [[loop-gap resonator]] (LGR) is made by cutting a narrow slit along the length of a conducting tube.  The slit has an effective capacitance and the bore of the resonator has an effective inductance.  Therefore, the LGR can be modeled as an RLC circuit and has a resonant frequency that is typically between 200 MHz and 2 GHz.  In the absence of radiation losses, the effective resistance of the LGR is determined by the resistivity and electromagnetic skin depth of the conductor used to make the resonator.

One key advantage of the LGR is that, at its resonant frequency, its dimensions are small compared to the free-space wavelength of the electromagnetic fields.  Therefore, it is possible to use LGRs to construct a compact and high-Q resonator that operates at relatively low frequencies where cavity resonators would be impractically large.