The double coupled microwave resonance probes and application for diagnosing atmospheric pressure plasma jet

The double-coupled microwave resonance probe(DMRP)based on the hairpin probe is proposed for diagnosing atmospheric plasma jet(ne<1017 m-3).In this work,the resonance characteristics of DMRP are investigated by numerical simulation.It shows that two resonance peaks on the reflectance spectrum can be observed,and influenced significantly by some parameters,such as the probe separation,the distance to the handheld radio frequency atmospheric pressure glow discharge plasma jet(RF-APGDPJ)and the plasma electron density less than 1017 m-3.Based on two resonance modes of DMRP,the electron densities in the afterglow of RF-APGDPJ at the different rf powers and helium flow rates are diagnosed experimentally by matching the change of FWHM(Df1-Df1,airand Df2-Df2,air)measured by vector network analyzer with the simulated relation between the FWHM changes and the plasma density.

Charge noise acting on graphene double quantum dots in circuit quantum electrodynamics architecture

We investigate the dephasing mechanisms induced by the charge noise and microwave heating effect acting on a graphene double quantum dot （DQD） capacitively coupled to a microwave resonator. The charge noise is obtained from DC transport current, and its contribution to dephasing is simultaneously determined by the amplitude response of the microwave resonator. A lowfrequency 1/f-type noise is demonstrated to be the dominant factor of the dephasing of graphene DQD. Furthermore, when the applied microwave power is larger than -90 dBm, the dephasing rate of graphene DQD increases rapidly with the increase of microwave power, and fluctuates slightly with the applied microwave power smaller than -90 dBm. Our results can be applied to suppress the impeditive influence on the dephasing of graphene-based devices associated with microwave input in the perspective investigations.

Single Mode DR Filters for Wireless Base Stations

This paper presents state-of-the-art high Q single-mode dielectric resonator （DR） cavity filters for PCS wireless base stations. DR cavity filters shrink the cavity size significantly more than waveguide cavity filters and offer about twice higher Q than coaxial resonators. Thus, they have important applications in wireless base stations operating below 2.5 GHz. Dual-mode and triple-mode DR cavity filters have existed for a while; however, single-mode DR cavity filters are predominant because they are cheaper to manufacture. This paper summarizes the main characteristics of TE01 mode DR cavities, including mode chart and field distribution, and compares cavity Q with waveguide and combline （coaxial） cavities. Dielectric combline and TM010 mode DR cavities are analyzed and compared to TE01 mode DR cavities. General filter design techniques are discussed, and several design examples are given to show how filter technology has developed.

Microwave frequency upconversion employing a coupling-modulated ring resonator

We present a method to generate a frequency-doubled microwave signal by employing a coupling-modulated ring resonator. Critical coupling is achieved when the resonator intrinsic loss is perfectly balanced by the external coupling enabled by a Mach–Zehnder interferometer coupler. The high suppression of the carrier leads to a clean two-tone optical signal with the frequency interval two times larger than that of the input microwave frequency.The beating of the two-tone signal at a photodiode generates the frequency upconverted microwave signal.A theoretical model is established to analyze the modulation process and the microwave signal generation.Experimental results show that the electrical harmonic suppression ratio is around ~20 dB(29 dB) for an input microwave signal with 5 dBm(10 dBm) power.

Light induced microstructure transformation in a-Si：H films

A series of a-Si：H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition （HW-MWECR-CVD）, subsequently exposed under simulated illumination for three hours. This paper studies the microstructure change during illumination by Fourier Transformation Infrared （FTIR） spectra. There are two typical transformation tendencies of microstructure after illumination. It proposes a model of light induced structural change based on the experimental results. It is found that all samples follow the same mechanism during illumination, and intrinsic structure of samples affect the total H content.

Lumped modeling with circuit elements for nonreciprocal magnetoelectric tunable band-pass filter

This paper presents a lumped equivalent circuit model of the nonreciprocal magnetoelectric tunable microwave bandpass filter.The reciprocal coupled-line circuit is based on the converse magnetoelectric effect of magnetoelectric composites,includes the electrical tunable equivalent factor of the piezoelectric layer,and is established by the introduced lumped elements,such as radiation capacitance,radiation inductance,and coupling inductance,according to the transmission characteristics of the electromagnetic wave and magnetostatic wave in an inverted-L-shaped microstrip line and ferrite slab.The nonreciprocal transmission property of the filter is described by the introduced T-shaped circuit containing controlled sources.Finally,the lumped equivalent circuit of a nonreciprocal magnetoelectric tunable microwave band-pass filter is given and the lumped parameters are also expressed.When the deviation angles of the ferrite slab are respectively 0° and45°,the corresponding magnetoelectric devices are respectively a reciprocal device and a nonreciprocal device.The curves of S parameter obtained by the lumped equivalent circuit model and electromagnetic simulation are in good agreement with the experimental results.When the deviation angle is between 0° and 45°,the maximum value of the S parameter predicted by the lumped equivalent circuit model is in good agreement with the experimental result.The comparison results of the paper show that the lumped equivalent circuit model is valid.Further,the effect of some key material parameters on the performance of devices is predicted by the lumped equivalent circuit model.The research can provide the theoretical basis for the design and application of nonreciprocal magnetoelectric tunable devices.