Jia Wei Yu

Wideband Dual-Polarization Patch Antenna Array With Parallel Strip Line Balun Feeding

A wideband dual-polarization patch antenna array is proposed in this letter. The array is fed by a parallel strip line balun, which is adopted to generate 180° phase shift in a wide frequency range. In addition, this balun has simple structure, very small phase shift error, and good ports isolation. The working band of the antenna array is from 1.88 to 2.9 GHz with a relative bandwidth of 41.7%. The height of the antenna array is only 0.144λ, and the cross polarization is below -20 dB. Two feeding ports are presented, which correspond to two orthogonal linear polarization. The isolation between the ports is higher than 30 dB. The simulation and measurement turns out to be similar. This antenna array can be used in TD-LTE base stations, and the design methods are also useful to other wideband microstrip antennas.

Electromagnetically induced transparencies in a closed waveguide with high efficiency and wide frequency band

We propose an effective method to alleviate the conflict between large group delay and wide frequency band in electromagnetically induced transparency (EIT) design. Two kinds of electrically induced transparency (E-IT) and magnetically induced transparency (M-IT) are proposed, respectively. Then an EIT with wide transparency window is developed by combining the independent E-IT and M-IT structures. All of the transparencies are designed in a closed waveguide system, and high efficiency is obtained at the same time. One sample is fabricated and the bandwidth is increased to more than 3 times without decrease of the group delay and increase of the size.

An EIT-Based Compact Microwave Sensor With Double Sensing Functions

Microwave sensors, which utilize the peculiarity of microwave to detect conditions and status of an object, have been widely used in electromechanical conversion, biochemical sensing, and environmental monitoring. In this paper, the concept of electromagnetically induced transparency (EIT) is adopted in the sensor design, and a compact microwave sensor is proposed with double sensing functions and works well under different electromagnetic conditions. High sensitivities of 13.709 mm/refract index unit for the EIT-window response and 10.6 MHz/fF for the dark mode operation are obtained, respectively. The proposed sensor is simulated, fabricated, and tested. Good agreement is obtained between the simulation and measurement results.

A Band-Notched Absorber Designed With High Notch-Band-Edge Selectivity

In this paper, a band-notched absorber with high notch-band-edge selectivity is proposed and investigated. It is formed by introducing a narrower and full reflectance band into a wider absorption band. For each absorbing unit cell, two independently magnetic and electric resonances with adjacent resonant frequencies are employed to develop the narrower and full reflectance band, while a dipole-shaped metal strip with a resister printed on one side of the supporting substrate and a ground plane is used to realize the wider absorption band. By retrieving relative equivalent circuits of each cell, the performance of the proposed absorber can be qualitatively analyzed. Simply through tuning the frequencies of the independently magnetic and electric resonances, the performance of the notched band can be adjusted with high notch-band-edge selectivity. A sample of an absorber with the notched band frequency from 8.2 to 9.8 GHz, good absorption band from 4.8 to 8.0 GHz and 10.2 to 16 GHz has been designed, fabricated, and measured. Good agreement among circuit analysis, simulation results, and measurement results is finally obtained.

Understand and Realize an ``Invisible Gateway'' in a Classical Way

We create an invisible gateway simply by putting electric and magnetic superscatterers in a metallic waveguide. The characteristics of the electric and magnetic resonators are analyzed in a metallic hollow waveguide, and the dual-mode superscattering property is discussed in detail to broaden the bandwidth of the invisible gateway. Good agreement is achieved between the simulation and measurement for such an invisible gateway. The present work help readers understand easily how an invisible gateway works (or makes sense) in a classical way without using any complex metamaterial or complicated method of transformation optics.

Design and Analysis of EMIT Filter and Diplexer

In this paper, a novel design of an E-plane waveguide filter, called electromagnetically induced transparency (EMIT) filter, is proposed. This EMIT filter is implemented by a rectangular ring (RR) on one side of the substrate and two strip lines resonators (SLRs) on the opposite side, which brings in electrically induced transparency and magnetically induced transparency by the electrical and magnetic couplings between the RR and SLRs, respectively. An equivalent circuit is developed further. Properties of high selectivity, low insertion loss, flat group delay, and small size of only about 0.2λg are realized by this design method. A sample has been fabricated and tested. The measured central frequency is 33.77 GHz with 3-dB fractional bandwidth of 9.4% and the minimum insertion loss in the passband is 0.5 dB. Using the proposed miniature EMIT filter, a diplexer is further designed with compact sizes and low insertion losses. The measured minimum insertion losses are 0.9 and 0.5 dB in the lower and upper passbands centered at 31.79 and 34.74 GHz with 3-dB relative bandwidths of 7.2% and 8.6%, respectively. Good agreements between the simulated and measured results are obtained both in the EMIT filter and the EMIT diplexer.

Investigations on cooling of cavity for power combiner

Cooling is very important for a high power combiner. This paper presents a thermal analysis on the cooling of cavity for power combiners. In this study, we concentrate on the influence from heat sink, cover of the cavity and the gaps between cavity and heat sink. At last the simulation result shows that aluminum box with copper plated on its outer surface can significantly reduce the maximum temperature of the cavity, which will improve the cooling of the power combiner.