A compact broadband power divider based on spoof surface plasmon polaritons

Abstract

In this letter, a compact broadband spoof surface plasmon polaritons (SPPs) power divider based on the coupled mode theory with excellent transmission efficiency is proposed. An equal power divider is constructed in order to divide the energy of spoof SPPs equally between the two output ports into two equal parts with good isolation. This coupling method consists of four coupling units which are designed near the input port for splitting the energy towards the two output ports. The energy is transferred not only through spoof SPPs but also through the coupling units. The coplanar waveguides with 50 Ω impedance have been designed for feeding or extracting signals at three ends of the spoof SPP waveguide. According to the coupled mode theory, the fields of SPPs along a single waveguide in a specific frequency range can be readily coupled into two adjacent branch waveguides with the same propagation constants. This technique has been adopted for impedance matching in a 3-port lossy network. The simulations showed that the two output ports can be efficiently driven by the input port. The S-parameters and near-field results are also provided to verify the performance of the proposed power divider. The proposed spoof SPPs based power divider will find many innovative applications and will be an important addition towards the development of advanced plasmonic circuits at the microwave and terahertz frequencies.