Miniaturized High-Order-Mode Dipole Antennas Based on Spoof Surface Plasmon Polaritons

A miniaturization method for antennas is developed based on spoof surface plasmon polaritons (SSPPs). With a large phase constant on the SSPPs transmission line, the guide wavelength can be dramatically reduced, with great potential on the miniaturization application of antennas. By introducing a miniaturization factor M, the relationship between M and the phase constant on the SSPPs dipole is studied, providing guidance to the design of miniaturized SSPPs dipoles. Then, SSPPs dipoles operating at 2.4 GHz are designed, including both the odd- and even-resonance dipoles. Simple feeding structures are developed for the odd- and even-resonance dipoles, respectively, and particularly for the even-resonance mode to realize a transition from 50 Ω to very large input impedance of the dipole. The miniaturized SSPPs dipoles operating at the 1st, 2nd, 3rd, and 4th modes are fabricated. The measured reflection coefficients and radiation patterns show good agreements with the simulated results. It can be concluded that the dipole lengths for these modes are reduced by 8%, 11%, 10%, and 13%, respectively, compared with the conventional printed dipoles on the same substrate.