In this letter, a rectangular waveguide with controlled negative group delay (NGD) is proposed. The equivalent circuit of the structure is proposed and analyzed. The NGD value and NGD center frequency can be adjusted continuously by the corrugation width and height. Simulation results showed that NGD values of up to -0.7 ns were achievable. The fractional bandwidth was up to 5.67, at which point the NGD response was observed. A prototype of the proposed structure was fabricated and characterized. Results showed that the fabricated structure was capable of generating a group delay of up to -0.09 ns at 18.9-20 GHz, which was consistent with theoretical and simulated predictions. To the best of our knowledge, this is the first time negative group delay has been achieved in the microwave-band in a rectangular waveguide.
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