Yujiro Kushiyama

Experimental verification of spoof surface plasmons in wire metamaterials.

In this paper, we experimentally demonstrate the excitation of spoof surface plasmon polaritons (SPPs) on a wire-medium metamaterial slab in the microwave region. The spoof SPPs are excited on the opposite side of the slab from the source, which is desirable for applications such as sensing devices. Using the prism coupling method, we verify the excitation of spoof SPPs by measuring the reflection spectrum and near-field enhancement. The excitation of spoof SPPs is also verified by using the grating coupling method, where we demonstrate transmission enhancement through the metamaterial slab by placing diffraction gratings on both sides of the slab. Numerical investigation shows that the enhanced transmission can be attributed to the dispersion relations of the spoof SPPs and the periodicity of the diffraction grating. These properties can be used to realize extraordinary transmission and directional beaming.

Differential-Type CRLH Leaky-Wave Antenna Using Stepped Impedance Resonators

A composite right/left-handed (CRLH) leaky-wave antenna (LWA) using a stepped impedance resonator (SIR) is presented. By applying the SIR technique to a conventional CRLH structure, a balanced condition is achieved through the adjustment of the SIR parameters. Therefore, the structure requires no interdigital or multilayered capacitor to achieve the balanced condition. A differential microstrip configuration is also used for the utilization of a virtual ground to eliminate the need for ground vias. The simplicity of the structure allows for applications at high frequencies. An LWA consisting of 14 unit cells of the proposed structure is designed and measured. Continuous beam scanning from the backward direction to the forward direction is demonstrated.

Near-Field Far-Field Transformation Utilizing 2-D Plane-Wave Expansion for Monostatic RCS Extrapolation

Near-field far-field transformation (NFFFT) is a common solution to the huge costs associated with the radar cross section (RCS) measurements. One such NFFFT technique for the monostatic RCS measurement has been proposed, which utilizes the 3-D plane-wave expansion. While the technique has the higher flexibility, its use of 3-D near-field scans is costly. In this letter, we propose a 2-D version of the NFFFT that utilizes the 2-D plane-wave expansion. Thus the one-cut-plane RCS can be obtained by measuring only on a plane with the higher flexibility.

A microstrip composite right/left handed leaky-wave antenna using a stepped impedance resonator

A composite right/left-handed (CRLH) leaky wave antenna using a stepped impedance resonator (SIR) is presented. By applying the SIR technique to a conventional CRLH structure, a balanced condition is achieved through adjustments of parameters of the SIR. Therefore, the structure requires no interdigital or multilayer capacitor to achieve a balanced condition. A differential microstrip geometry is also used for utilizing a virtual ground to remove grounded vias. The simplicity of the structure allows applications at higher frequencies. A leaky wave antenna consists of 14 unit cells of the proposed structure is designed. A continuous beam scanning capability from backward to forward direction is confirmed.