Dual Frequency Oscillator Using Gunn Diodes with a Frequency Dependent Mode Converter

When electromagnetic waves with two frequencies that differ by a factor of two propagate in a metallic waveguide, it is difficult to propagate only the TE
₁₀
mode without the TE
₂₀
mode for higher frequency region. We propose a TE
₁₀
-mode-only source using two wave sources whose frequencies differ by a factor of two with a frequency-dependent mode converter. The TE
₁₀
-mode source is composed of an oscillator section and a mode converter section. Gunn diodes of 10 and 20 GHz are used to generate the electromagnetic waves. The oscillator section also has five dielectric rods centered in a metallic waveguide in order to pass the TE
₁₀
mode at 10 GHz and suppress the TE10 mode at 20 GHz without influencing the TE
₂₀
mode. In the mode converter section the 10-GHz TE
₁₀
mode is passed and the 20-GHz TE
₂₀
mode is converted to the TE
₁₀
mode, so that the output is solely TE
₁₀
mode. We experimentally confirmed the functioning of the converter.