Miniaturization of Monopole Antenna Based on Spoof Surface Plasmon Polaritons

The development of communication technology and the expansion of spectrum have brought the urgent demand for antenna miniaturization. In this letter, a method of miniaturizing the monopole antenna, which is based on the deep-subwavelength property of the spoof surface plasmon polaritons (SSPPs), is proposed. The SSPP monopole antenna is composed of an SSPP structure and an interdigit capacitor near the feeding structure for impedance matching. The antenna height is determined by engineering the dispersion curves of the SSPPs. The SSPP structure is fed by an SMA connector whose ground is connected to a finite circular metal plate. For verification, an SSPP antenna working at around 2.4 GHz is designed, fabricated, and measured. The profile of the SSPP monopole antenna is reduced to 11.7% of the wavelength in free space. The simulation and experimental results both show that the low-profile SSPP antenna has high-efficiency omnidirectional radiation with low cross polarization in the operating band. The peak gain at 2.4 GHz is up to 4.59 dBi. This letter provides an effective alternative to design a low-profile monopole antenna and has great potential in the miniaturization of the antenna.