Broadside radiation antenna based on tightly coupled spoof surface plasmon polaritons

A spoof surface plasmon polariton (SSPP) is a hybrid mode of a surface wave in the air and electron oscillation within artificial electromagnetic (EM) media, with the dispersion curve lying below the light line, giving rise to many unique EM properties. In this paper, we investigate the EM properties of tightly coupled SSPP (TC-SSPP) modes and propose a slender broadside antenna based on the TC-SSPP. With the comb structure (CS), dispersion properties of different SSPP modes are firstly analyzed under plane wave illumination, and then we introduce a modified SSPP structure, the broadside-coupled (BC)-CS, to excite and guide TC-SSPP modes. Since TC-SSPP modes can be confined tightly around the slender BC-CS, EM waves can be manipulated within a much more compact space, which is favorable for miniaturization, compactness and the light weight of microwave devices. To demonstrate this, we propose a slender broadside radiation antenna based on the TC-SSPP, using a probe as the feed and a finite-length BC-CS as the radiator. Due to near-field magnetic coupling, the SSPP wave can be excited on the BC-CS. By varying the geometric parameters, the antenna can radiate in the broadside direction. A prototype was designed, fabricated and measured. Both the simulated and measured results verify our design.

Automated summary

In this paper, the electromagnetic properties of tightly coupled spoof surface plasmon polariton (SSPP) modes and a slender broadside antenna based on the tightly coupled SSPP are investigated and proposed. The compactness and miniaturization of microwave devices are favored by the tight confinement of TC-SSPP modes around the slender structure. A prototype of the proposed antenna was designed, fabricated, and measured, with both simulated and measured results verifying the design.