Chao Li

Bio: Chao Li is an academic researcher from Xidian University. The author has contributed to research in topics: Slot antenna & Dipole antenna. The author has an hindex of 1, co-authored 3 publications receiving 3 citations.

A Novel Center-Fed SIW Inclined Slot Antenna for Active Phased Array

Abstract: In this paper, a center-fed substrate integrated waveguide (SIW) inclined slot array antenna is designed for a one-dimensional active phased array. A novel coaxial-to-SIW transition is employed to realize the central feed for enhancing bandwidth. The antenna prototype printed onto a single-layer Rogers 5870 is composed of 32 × 16 inclined slots working at Ku-band. As shown in measured result, the bandwidth with return loss < −10 dB is from 16.6 to 17.1 GHz, and the sidelobe levels of arrays are below −24.8 dB at 16.8 GHz in H planes. The measured gain is 31.8 dB at 16.8 GHz with the aperture efficiency of 65%. The active phased array is assembled by an antenna and 32 Tx/Rx modules, and the measured results show that the main lobe can obtain a wide-angle scanning from −45 to 45 degrees in E planes. The antenna array is suitable for low profile small active phased array radars and communication systems that require spatial wide-angle scanning.

Ultra‐high‐frequency wideband circularly polarized crossed‐dipole antenna with wide axial‐ratio beamwidths for SATCOM applications

Abstract: In this study, an ultra-high-frequency (UHF) wideband circularly polarized (CP) crossed-dipole antenna with wide axial-ratio beamwidth (ARBW) is proposed for SATCOM applications. The antenna is composed of two pairs of dipoles with umbrella-shaped arms, and they are fed by a feeding network to generate CP radiation. Two pairs of parasitic patches are introduced symmetrically between the dipole arms and the ground plane. Due to coupling of the dipoles, currents can be induced on to the metal patches, which can not only decrease the antenna volume by increasing the current path of the dipole arms, but also additional radiation can be provided to enhance the ARBW. A prototype of proposed antenna was fabricated and measured. The measured results indicate that it operates at the UHF band ranging from 280 to 420 MHz, with a –10-dB impedance bandwidth of 40.5% and a 3-dB AR bandwidth of 42%. Furthermore, the antenna exhibits a 3-dB ARBW of more than 190 within a wide operating band of 23.1%.

Near-field terahertz probes with room-temperature nanodetectors for subwavelength resolution imaging

Abstract: Near-field imaging with terahertz (THz) waves is emerging as a powerful technique for fundamental research in photonics and across physical and life sciences. Spatial resolution beyond the diffraction limit can be achieved by collecting THz waves from an object through a small aperture placed in the near-field. However, light transmission through a sub-wavelength size aperture is fundamentally limited by the wave nature of light. Here, we conceive a novel architecture that exploits inherently strong evanescent THz field arising within the aperture to mitigate the problem of vanishing transmission. The sub-wavelength aperture is originally coupled to asymmetric electrodes, which activate the thermo-electric THz detection mechanism in a transistor channel made of flakes of black-phosphorus or InAs nanowires. The proposed novel THz near-field probes enable room-temperature sub-wavelength resolution coherent imaging with a 3.4 THz quantum cascade laser, paving the way to compact and versatile THz imaging systems and promising to bridge the gap in spatial resolution from the nanoscale to the diffraction limit.

Wideband SIW Slot-Array Design Based on Reflection-Slope-Synthesis Method for 5G Services

Abstract: In the last decade, substrate integrated waveguide (SIW)-based solutions have been successfully introduced as a proper compromise between conventional strip and waveguide technologies, allowing the implementation of typical waveguide structures on planar circuits, as slot arrays. In this letter, a new technical approach to design wideband antennas by using radiant slots, which are usually considered narrow-band structures, is presented. Commonly, an equivalent circuit composed of admittances, whose conductance and susceptance are computed by well-known analytic methods, is widely used to design slot arrays. However, they are aimed at narrow-band services. The new synthesis method is based on the slope of the S -parameters and the impedance shown by the slots to optimize their position and distribution along the SIW to achieve the broadband-impedance performance, as well as a least-mean-square (LMS) system to mitigate the beam-squint effect and not to degrade the beam bandwidth. The novel antenna presents a relative impedance bandwidth above 20%, by using four slots, while keeping the beam bandwidth and a radiation efficiency higher than $-$ 0.7 dB.

High Performance Millimeter Wave SIW Slotted Array Antenna

Abstract: |A high performance substrate integrated waveguide (SIW) slotted array antenna with low sidelobe level and optimum gain at 28 GHz is designed, and experimental results are presented with simulated data. In order to achieve a low sidelobe level, Chebyshev power coefficients in the form of slot displacements are applied to the SIW array antenna. A MATLAB program has been written to (cid:12)nd these slot displacements. This work entails investigating and designing the optimum microstrip to SIW transition over the Ka-band, designing a 1 (cid:2) 8 slotted SIW array antenna, and (cid:12)nally applying the Chebyshev power coefficients to the slots of the 1 (cid:2) 8 SIW array antenna. The fabricated prototype of a 1 (cid:2) 8 SIW slotted array antenna is tested, and its performance is studied in terms of gain and half power beam width (HPBW), compared with simulations. The measured results of the 1 (cid:2) 8 slotted SIW array antenna at 28 GHz have a j S 11 j of better than (cid:0) 20 dB, a gain of 13 dB, and an HPBW of 17 ◦ . The overall dimensions of the design at 28 GHz are 7 : 143 mm (cid:2) 51 : 8 mm (cid:2) 0 : 254 mm (0 : 667 (cid:21) o (cid:2) 4 : 84 (cid:21) o (cid:2) 0 : 023 (cid:21) o = 0 : 0766 (cid:21) 3 o mm 3 ).