X-Band Miniaturized Klystron With Metamaterial-Inspired Interaction Structure

A novel metamaterial-inspired interaction structure is proposed to construct an X-band miniaturized klystron. The transverse dimension miniaturization of a resonant cavity is investigated by loading a subwavelength metamaterial unit cell with high mechanical strength, i.e., four-groove complementary electric split-ring resonator (FGCeSRR). The radius and length of the metamaterial-inspired interaction structure are ~0.8 and ~0.79 of the counterpart, respectively, resulting in a volume reduction of ~50%. The beam–wave interaction of the klystron is then predicted by CST PIC. Under the conditions that the beam voltage is 45 kV, the beam current is 8 A, and the uniform longitudinal magnetic flux density is 0.5 T, the output power reaches 187 kW, the gain is 49.7 dB, and the electronic efficiency attains 52% at 9.5 GHz. The compact size and high performance make this metamaterial-inspired klystron useful for future radar applications.