Jing Jing Yang

Mu and epsilon near zero metamaterials for perfect coherence and new antenna designs

Wave interference is a fundamental physical phenomenon. Traditionally, the coherent effect of two identical point sources only takes place when the optical path is an integer number of wavelengths. In this paper, we show that mu and epsilon near zero (MENZ) metamaterials can be used to realize a perfectly constructive and isotropic interference. No matter how many point sources are embedded in the MENZ region, the wavefronts overlap perfectly. This translates into a total relaxation of the conventional condition for coherence enabled by the apparent infinite wavelength of the fields within MENZ metamaterials. Furthermore, we investigate crucial parameters such as the shape and size of the MENZ region. We demonstrate that flat sided geometries give rise to constructive interference beams serving as a powerful design mean. We also reveal the importance of relying on deeply sub-wavelength MENZ volumes as larger sizes increase the impedance and therefore reduce the output power of the device. The proposed concepts bear significance for current trends in antenna design which are inspired by the recent developments of electromagnetic metamaterials. Moreover, the perfect coherence effect can be appealing for power combiners, especially in the terahertz where sources are dim, as the irradiation intensity scales with the square of the number of embedded sources.

Wireless OAM transmission system based on elliptical microstrip patch antenna.

The multiplexing transmission has always been a focus of attention for communication technology. In this paper, the radiation characteristics of circular microstrip patch antenna was firstly analyzed based on cavity model theory, and then spiral beams carrying orbital angular momentum (OAM) were generated, using elliptical microstrip patch antenna, with a single feed probe instead of a standard circular patch with two feedpoints. Moreover, by combining the proposed elliptic microstrip patch antenna with Universal Software Radio Peripheral (USRP), a wireless OAM transmission system was established and the real-time transmission of text, image and video in a real channel environment was realized. Since the wireless OAM transmission has the advantage of good safety and high spectrum utilization efficiency, this work has theoretical significance and potential application.

Manipulating the field distribution of a polygonal SPP resonator based on AZIM

A method for controlling the field distribution of a polygonal surface plasmon polariton (SPP) resonator based on anisotropic zero-index metamaterial (AZIM) is proposed and verified by numerical simulations. Results show that radiation loss at the corner of the polygon SPP resonator can be suppressed; the AZIM is also capable of adjusting the mode number and controlling the field distribution in an SPP resonator. Finally, the AZIM eliminates the transmission delay of surface waves and breaks the limitation of a mode number in direct proportion to the perimeter of the resonator. This may open up a new avenue for manipulating the mode number of SPP resonators at will.

Surface WGM sensor based on a cylindrical dielectric waveguide

The dispersion equation of a layered cylindrical dielectric waveguide operating in the whispering gallery mode (WGM) is derived. We demonstrate that when the waveguide is coated with a negative permittivity layer, a surface WGM can be generated. It exposes a strong evanescent field to the ambient substance, rendering the negative permittivity material assisted microring sensor much more sensitive to a slight change in surrounding medium. This opens up an avenue towards designing optical WGM sensors with superior performance.

Cooperative compressed spectrum sensing model for regional radio monitoring

Detection and direction finding of illegal emission source is the core issue of radio monitoring network. However, the performances of traditional fixed stations and mobile stations which are based on energy detection and work individually are often compromised with multipath fading and shadowing in urban environment. To mitigate the impact of these issues, a cooperative compressed spectrum sensing model which consists of several sensing nodes and a fusion node is proposed in this paper. The maximum-minimum eigenvalue based detection method is applied to the sensing model. Simulation results show that cooperative compressed sensing provides an efficient way to sense radio signal which is sparse at frequency domain.

State of the Art and Challenges of Radio Spectrum Monitoring in China

This paper provides an overview of radio spectrum monitoring in China. First, research background, the motivation is described and then train of thought, the prototype system, and the accomplishments are presented. Current radio spectrum monitoring systems are man-machine communication systems, which are unable to detect and process the radio interference automatically. In order to realize intelligent radio monitoring and spectrum management, we proposed an Internet of Things-based spectrum sensing approach using information system architecture and implemented a pilot program; then some very interesting results were obtained.

State-of-the-art and challenges of Radio spectrum monitoring in borderlands of China

This paper provides an overview of radio spectrum monitoring in borderlands of China. Firstly research background, the motivation, accomplishments are described and then plans for future work in China are presented. Current radio spectrum monitoring systems are man-machine communication systems based on Radio Monitoring Transfer Protocol (RMTP), which are unable to detect and process the radio interference automatically. In order to realize intelligent radio monitoring and spectrum management in the future, we proposed a cloud-based spectrum sensing approach using information system architecture.

A method for on-line measurement and calibration of fixed radio monitoring stations

As the demand for refined spectrum management grows, the need for accurate and reliable radio monitoring data increases accordingly. In this context, the calibration of radio monitoring stations has become a routine work for efficient spectrum management. In this paper, an on-line measurement and calibration method in Open Air Test Site (OATS) is described, followed by experimental verification. The results show that on-line measurement and calibration is very important for improving the accuracy and reliability of radio monitoring data and thus provides effective technical support for spectrum management and audit.

An automatic radio monitoring and early warning architecture based on C/S for illegal broadcasting

Current radio spectrum monitoring systems are “man-machine” communication systems based on Radio Monitoring Transfer Protocol (RMTP), which are unable to detect and process the radio interference automatically. In this paper an automatic radio monitoring and early warning architecture based on C/S model and internet protocol is proposed. A pilot “machine-machine” system which consists of several sensor nodes and an application & service (A&S) center for monitoring and early warning to illegal broadcasting is implemented using Baidu map JavaScript API technology and Windows Presentation Foundation (WPF). The sensor node is a RTL-SDR connected to an industrial computer. It mainly takes charge of illegal signal detection, early warning and monitoring data storing. Whats more it provides a web service for the A&S center to retrieve the monitoring data in a fixed time interval for further data presentation and statistical analysis.

Metamaterial-inspired sensor based on a complementary asymmetric double-split resonator

Based on the Babinet Principle, a new metamaterial sensor is proposed in microwave region. The main part of the device is a microstrip coupled complementary asymmetric double-split resonator (CADSR). In this device, an extremely sharp resonance have been obtained due to the excitation of “trapped modes”. From the analysis, the effect of the degree of asymmetry on the frequency response and Q-Factor are thoroughly studied. Results show that there have an upward tendency of Q-Factor when increasing the degree of asymmetry, the distribution of the electric field and transmission response (S2i) have been also simulated in this work. Finally, the process and the performance is illustrated when CADSR is used as a sensor. We found that both dielectric constant and loss tangent of sample substance affect the resonance frequency. It is demonstrated that the reflection spectrum shift to lower frequency side when enhancing the permittivity of sample substance which is filled in groove. Furthermore, the CADSR will increase the contact area with field and sample, and the relation between resonant frequency and the sample permittivity exhibits a perfect linearity.