On-chip dual-mode transmission line with spoof surface plasmon based on balun

An on-chip dual-mode transmission line with a spoof surface plasmon based on a balun, wherein a dual-mode transmission line structure comprises a dielectric adhesive, a dielectric material, a metal ground structure, metal strip lines, odd-mode signal pads, even-mode signal pads, four-port grounding, and a dual-mode transmission line located in an intermediate of the dual-mode transmission line structure, a balun structure symmetrically located at both terminals of the dual-mode transmission line, and a pad feeding structure located outside each of the balun structure;

• the dual-mode transmission line includes two metal strip lines parallel to each other and branches located between the two metal strip lines;
• each of the balun structure is formed by coupling two layers of metal structures, including upper metal meander lines, a lower metal meander line, a main feeding line, and a metal connection line;
• pads of each of the pad feeding structure include the odd-mode signal pad, the even-mode signal pad and the four-port grounding terminals, each of the four-port grounding terminals is in a cuboid metal via structure, and is configured to connect a metal layer where the dual-mode transmission line is located with the metal ground structure covered under the dielectric material;
• connection lines of each of the pad feeding structure are signal connection lines led out from the odd-mode signal pad and the even-mode signal pad, including the metal connection line and the main feeding line;
• the lower metal meander line is in a C-shape, the odd-mode signal pad is connected to one terminal of the lower metal meander line through the metal connection line, and the even-mode signal pad is connected to a ring line through the main feeding line;
• the two metal strip lines are respectively connected at openings of each of the ring lines, and both ports of each of the two metal strip lines are respectively connected to an inward port of each of the upper metal meander lines, the inward port is a port facing towards an intermediate of the transmission line structure;
• two outward ports of the two upper metal meander lines are suspended in midair.