Design and Analysis of an Adjustable Diode-Integrated Waveguide-Based Electromagnetic Pulse Limiter for Microwave Receiver

A new waveguide-based diode limiter is proposed to protect microwave-amplifying receivers from high-power electromagnetic pulses. The diode limiter was designed and fabricated to exhibit low insertion loss for normal signals while effectively blocking high-power transient signals. The proposed structure incorporates a diode element positioned between vertically connected cylinders inside the waveguide, with a square-integrated structure symmetrically placed on both the top and bottom. The diode element is inserted beneath a thin rod. Under low incident power, the diode remains inoperative, maintaining an electrically open state. In the presence of high incident power, the diode activates, transitioning into an electrically short state. The newly proposed structure enables the cylinder’s vertical movement, providing the advantage of adjustability to shift the center operating frequency of the diode limiter. It incorporates a band-pass filter structure for normal signals and a band-stop filter characteristic for transient signals. Moreover, the symmetrical square-integrated structure is employed to concentrate the surface current at the diode element, enhancing the changing state of the diode limiter. This configuration demonstrates a low insertion loss of 0.38 dB for normal signals and a blocking coefficient of 8 dB for transient signals at the 5.68 GHz operating frequency.