Lower Voltage Operation of the Ledatron

We have successfully observed the millimetre wave oscillation in the Ledatron due to the TEM02 field distribution of the Fabry-Perot mode, which had been predicted by our theory of operation. Through operation of this mode, we can reduce an electron accelerating voltage about 10 percent to obtain the same oscillating frequency without any change of grating structures. The increase of the start-oscillation current is small when proper configuration of the resonator is chosen. The resonant characteristic of the grating has been examined experimentally and theoretically. The experimental results are in good agreement with our theory. The condition of the grating structure to give wide tuning range of the Fabry-Perot mode has been obtained by the theory. So far an output power of around 300 milliwatts has been obtained at 300-GHz band.