| 1. |
- Ding, Xuhui, et al.
(författare)
-
A 16 × 16-Element Slot Array Fed by Double-Layered Gap Waveguide Distribution Network at 160 GHz
- 2020
-
Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 8, s. 55372-55382
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, a slot array with double-layered full-corporate-fed distribution network by ridge gap waveguide (RGW) in the G-band is presented. The array antenna proposed in this article contains $16\times 16$ -element radiation slots fed by air-filled ridge gap waveguide distribution network that achieves high-efficiency. Gap waveguide technology avoids the demand for perfect electrical contact in millimeter waves, therefore the expensive diffusion bonding and the laser welding processes are not demanded. Moreover, the high-accurate Computerized Numerical Control (CNC) machining is applied for the fabrication. Due to the limited layout space for the distribution network, two types of universal stepped cavity power dividers are presented in this article. The proposed array antenna is fed by a standard WR-5 waveguide at the bottom. Furthermore, the tested outcomes show that the proposed $16\times 16$ -element array has a gain larger than 30 dBi with over 50% antenna efficiency in the frequency range of 155–171 GHz.
|
|
| 2. |
- He, Zhongxia Simon, 1984, et al.
(författare)
-
Integrated-EBG Ridge Waveguide and Its Application to an E-Band Waveguide 32×32 Slot Array Antenna
- 2020
-
Ingår i: IEEE Open Journal of Antennas and Propagation. - 2637-6431. ; 1, s. 456-463
-
Tidskriftsartikel (refereegranskat)abstract
- A methodology of designing an E-band waveguide 32×32 slot array antenna with high-efficiency and low-cost manufacturing characteristics is proposed in this article, which is based on an integrated electronic bandgap (EBG) ridge waveguide designed by integrating a cross rectangle-hollow EBG structures in the conventional ridge waveguide. The integrated EBG structure intercepts the leakage from the unconnected gap in between the two metallic plates of the waveguide, and then it decreases the manufacturing cost without using the diffusion bonding technology and multi-layer welding assembly process. The design guideline is discussed, and then the antenna is fabricated. The measured radiation characteristics are in good agreement with predicted ones, which confirms that the proposed cross rectangle-hollow EBG structures is an attractive candidate of high-performance millimeter wave antenna.
|
|
| 3. |
- He, Zhongxia Simon, 1984, et al.
(författare)
-
Variable High Precision Wide D-Band Phase Shifter
- 2020
-
Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 8, s. 140438-140444
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a new concept of designing compact high precision millimeter-wave wideband variable phase shifters. The phase shifter is implemented with a stacked shim with extremely short length of 0.9 mm and two waveguide flange adaptors with length of 0.5 mm. High precision phase shifting is achieved over entire D-band (110-170 GHz) by rotating the shim 90 degrees from aligned to perpendicular with consistent impedance matching performance. In addition, a glide-symmetric holey electromagnetic bandgap (EBG) structure is adopted to avoid wave leakage from the gap between the shim and the flange adaptors. A proof-of-concept (PoC) demonstrator is designed, manufactured, and tested. The measured results show that the designed stacked shim phase shifter with embedded EBG structure ensures return loss higher than 10 dB across 110-170 GHz with a 75 mu m airgap between waveguide flanges. The studied phase shifter provides a 0.88ffi phase shifting with each degree of mechanical rotation. The fabricated PoC phase shifter has a worst-case insertion loss of 0.92 dB and a return loss of 20 dB across the entire 110-170 GHz band and a maximum phase shift of 30 degrees. At 10 degrees phase shifting, the measured insertion loss is lower than 0.52 dB, and return loss is higher than 23 dB, respectively.
|
|
| 4. |
- Jin, Cheng, et al.
(författare)
-
Low-Cost mmWave Metallic Waveguide Based on Multilayer Integrated Vertical-EBG Structure and its Application to Slot Array Antenna Design
- 2022
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:3, s. 2205-2213
-
Tidskriftsartikel (refereegranskat)abstract
- A novel methodology to create metallic waveguides with multilayer integrated vertical-electromagnetic bandgap (EBG) structure is proposed in this article, and the structure realizes low-cost millimeter-wave (mmWave) slot array antennas. A multilayer stack of easy-to-process thin metallic etching plates is introduced to design mmWave waveguide using compression fit instead of diffusion bonding and welding assembly process. The electromagnetic (EM) wave leakage from the gaps between the metallic plates is suppressed using the vertical-EBG structure and antiphasing feeding. The dispersion diagrams of the vertical-EBG unit cell are investigated to illustrate the suppression of leakage. Another leakage wave intercepting methodology is adopted by antiphase feeding to prevent leakage wave from the adjacent slot subarrays. Finally, two examples of 2 $\times $ 8 and 8 $\times $ 8 slot array antennas are presented to verify our design concept. The measured impedance bandwidths of the two antennas are 77.1-84.6 GHz (9.3%) and 78.6-84.9 GHz (7.7%). In addition, the 3 dB broadside gain bandwidths are 73.1-85.3 GHz (15.1%) and 76.8-84.4 GHz (9.4%). The results show the aperture efficiencies up to 56.4%.
|
|
| 5. |
- Jin, Cheng, et al.
(författare)
-
Ultra-Wide-Angle Bandpass Frequency Selective Surface
- 2021
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 69:9, s. 5673-5681
-
Tidskriftsartikel (refereegranskat)abstract
- A novel theory is proposed in this paper to design a bandpass frequency selective surface (FSS) with a stable angular response. Based on this theory, the performance of the structure is closely related to its tangential and normal components of permittivity and permeability. Theoretical formulas are derived to realize a high-efficiency transmission response with angular independency. To validate our design concept, an ultra-wide-angle bandpass FSS with metallic strips and square patch printed on the dielectric substrate is designed, and it exhibits a characteristic impedance matching for nearly all incident angles from 0° to 80°. Moreover, varactor diodes are mounted at the center of the square patch, and the transmission window can be tuned by changing the capacitance of the varactors from 6.07 GHz to 6.61 GHz without affecting its ultra-wide-angle characteristic. Finally, a prototype of the tunable ultra-wide-angle bandpass FSS is fabricated and measured, and the experimental results are in satisfying agreement with the predicted ones.
|
|
| 6. |
- Sun, Xiaoming, et al.
(författare)
-
Adjustable hardness of hydrogel for promoting vascularization and maintaining sternness of stem cells in skin flap regeneration
- 2018
-
Ingår i: Applied Materials Today. - : Elsevier. - 2352-9407. ; 13, s. 54-63
-
Tidskriftsartikel (refereegranskat)abstract
- The matrix mechanical stiffness of biomaterials plays an important role in the pluripotency and biological function of stem cells in the microenvironment. It is a key step to adjust the stiffness of biomaterials for inducing stem cells to promote vascularization in order to promote damaged tissue repair. In this study, we transplant adipose derived stem cells (ADSCs) within an in situ forming dextran hydrogel with controllable mechanical strength formed by cross-linking glycidyl methacrylate derivatized dextran and dithiothreitol, which can regulate the stemness and biological functions of stem cells. We show that softer dextran hydrogel can better maintain stemness markers expression of ADSCs, and significantly stimulate ADSCs to secrete angiogenic factors. The ADSCs-encapsulated hydrogel distinctly promote the skin flap survival compared to direct cell injection. Bioluminescence imaging analysis shows that in situ forming dextran hydrogel can improve cells retention, and postmortem analysis reveals that the transplanted ADSCs with hydrogel can promote vascularization. These results support the use of injectable dextran hydrogel for skin ischemia tissue regeneration. (C) 2018 Elsevier Ltd. All rights reserved.
|
|
