Design of High-power Microwave Waveguide Divider

A new LHW antenna will be used in LHCD system on tokanak HT-7U, where a high-power microwave waveguide power divider is a key device. This paper presents the power divider structure whose coupling element is in the common narrow wall between two identical waveguides, a certain of which is completely excavated. Green's Function Method is used to analyze the electric field distributions of the structure, and consequently the graphs between the scattering matrix and the geometrical dimensions are given. The graphs can be straightly applied to the process of the power divider.

Excitation of anti-symmetric coupled spoof SPPs in 3D SIS waveguides based on coupling

According to the electromagnetic field distributions, there exist two kinds of coupled spoof surface plasmon polaritons（SSPPs）, the symmetric and anti-symmetric modes, in the three-dimensional（3D） subwavelength spoof–insulator–spoof（SIS） waveguide. We study the dispersion and excitation of the two kinds of coupled SSPPs supported by the 3D SIS waveguide. The evolution of the dispersion with the thickness and gap width of the waveguide is numerically investigated,and we give a theoretical analysis according to the coupling mechanism. Specially, based on the coupling mechanism,we design a zipper structure, through which the excitation and propagation of the anti-symmetric coupled modes can be realized effectively.

High quality factor superconducting coplanar waveguide fabricated with TiN

We fabricated TiN coplanar waveguides using standard lithography techniques followed by ICP etch. In order to achieve high quality factor, we investigated the film growth by choosing different deposition conditions for various substrates. Quality factors of waveguide resonators were measured at 20 mK in both high and low microwave power limits. An inner quality factor of several million was achieved at high power limit for a predominantly（200）-oriented TiN film which was grown on HF cleaned silicon wafer. A quality factor of larger than one million was achieved at high power limit for TiN film grown on sapphire.

Experimental evidence of photonic crystal waveguides with wide bandwidth in two-dimensional Al2O3 rods array

A cross-shaped photonic crystal waveguide formed by a square lattice Al_2O_3 rods array is numerically and experimentally investigated. The band gap of the TE mode for the photonic crystals and transmission characteristics of waveguides are calculated by the plane wave expansion method and the finite element method.We perform the experiments in the microwave regime to validate the numerical results. The measured reflection and transmission characteristics of the photonic crystals show a large band gap between 8.62 and 11.554 GHz（relative bandwidth is 29.34%）. The electromagnetic waves are transmitted stably in the waveguides, and the transmission characteristics maintain a high level in the band gap.