Wei He

Bio: Wei He is an academic researcher from Shenzhen University. The author has contributed to research in topics: Dipole antenna & Antenna (radio). The author has an hindex of 3, co-authored 18 publications receiving 158 citations. Previous affiliations of Wei He include City University of Hong Kong.

A Wideband Circularly Polarized Cross-Dipole Antenna

Abstract: This letter introduces a wideband circularly polarized (CP) cross-dipole antenna fabricated on a double-layered printed circuit board (PCB) substrate for 2.45-GHz ISM band wireless communications. Unlike conventional cross-dipole antennas, the proposed cross dipole is designed with wide open ends such that both impedance and axial-ratio (AR) bandwidths are enhanced. In addition, to excite the CP radiation effectively, a curved-delay line providing an orthogonal phase difference among the cross-dipole elements is attached at the corners of the sequentially rotated elements. By choosing a proper radius of the curved-delay line, a wide input impedance of the antenna can be realized. The antenna is center-fed by a 50- Ω coaxial cable and is placed above a square reflector to obtain a directional CP radiation pattern. With the advantage of centered feed, symmetric CP radiation patterns can be achieved across the entire operating bandwidth. Simulated and measured results confirm the proposed antenna produced good CP characteristics. An impedance bandwidth (for VSWR ≤ 2) of about 50.2% (1.99-3.22 GHz) and the 3-dB AR bandwidth of about 27% (2.30-2.9 GHz) around the center frequency of 2.45 GHz were measured. The antenna has an average CP gain of 6.2 dBic across the operating bandwidth and the maximum gain of 6.8 dBic at the center frequency. The size of antenna is 0.45λ×0.45λ×0.24λ.

Novel Reconfigurable Full-Metal Cavity-Backed Slot Antennas Using Movable Metal Posts

Abstract: Novel design concept of reconfigurable full-metal cavity-backed slot antennas (CBSAs) using movable metal posts is proposed in this article. It is found that the cavity mode with purely directional electric field is only affected by the metal post to be placed in parallel to its electric field. Thus, two orthogonal cavity modes TE101 and TE011 can be perturbed by two respective metal posts so as to independently tune the resonant frequencies of these two modes. Electromagnetic energy of the cavity modes can be radiated out through the slots on the top wall of the cavity. In this context, reconfigurable slot antennas with different functionalities, such as single-band, dual-band, dual-mode wideband, the tunable frequency with constant bandwidth, and tunable bandwidth with constant frequency, are thus constituted to demonstrate its attractive design feasibility. The frequency-reconfigurable cavity-back slot antenna with movable metal posts is proposed for the first time. The utilization of the metal posts allows us to achieve a continuous frequency tuning property, while the full-metal structure of the proposed antenna holds a high power-handling capacity and a high radiation efficiency. In final, a prototype of the dual-mode wideband slot antenna is designed, fabricated, and tested to reveal its total efficiency higher than 88% and stable radiation pattern over the tuning band. Good agreement between the measured and the simulated results well validates the presented design concept.

An Ultra-Wideband Circularly Polarized Asymmetric- $S$ Antenna With Enhanced Bandwidth and Beamwidth Performance

Abstract: This paper introduces an ultra-wideband circularly polarized (CP) asymmetric-S antenna with wide axial ratio beamwidth (ARBW) for C-band applications. The proposed antenna is realized by bending a linearly polarized dipole into asymmetric-S shape with variable trace width, which achieves CP radiation. Unlike the reported symmetric-S antenna, the proposed antenna is constituted with two unequal curved arms to enhance the bandwidth and beamwidth performances. Compared with the symmetric-S antenna, the proposed antenna demonstrates much wider AR bandwidth and wider ARBW over broader frequency range. A prototype is fabricated to verify the design principle. The measured and simulated results are very consistent and both indicate that the proposed antenna has a wide impedance bandwidth (VSWR <; 2) of 70.2% (3.58 to 7.46 GHz), and a wide 3-dB AR bandwidth of 84.8% (2.75 to 6.8 GHz). Moreover, maximum ARBW of 153° is achieved, and a 3-dB ARBW of more than 100° is maintained within a wide operation bandwidth of 46.3% (3.65-5.85 GHz).

Dual-Band and Tri-Band Parasitic Dipole Antennas for Wearable Applications

Abstract: Dual-band and triple-band(Tri-band) T-shaped dipole antennas with two couples of parasitic dipoles are proposed. Two or three resonances are realized by T-shaped printed dipoles and parasitic dipoles, respectively. The frequency of resonance depends on the width and length of parasitic dipoles. The proposed structure can achieve multiband operation. Both of the middle and upper operating frequencies can be easily controlled independently. Simulation results show that the maximum realized gains for tri-band antenna are 2.69 dBi, 1.65 dBi and 2.76 dBi at the resonant frequencies of 2.5 GHz, 4.6 GHz and 5.6 GHz, and the maximum realized gains for dual-band antenna are 3.11 dBi and 2.78 dBi at the operating frequencies of 2.5 GHz and 5.6 GHz. The proposed antennas are suitable for wearable applications.

A wideband circularly polarized S ‐shaped slot antenna

Abstract: Funding information Mobility Program for Taiwan Young Scientists, Grant/Award Number: RW2019TW001; National Natural Science Foundation of China, Grant/Award Numbers: 62071306, 61801299, 61871433; Shenzhen Science and Technology Program, Grant/Award Numbers: JCYJ20200109113601723, GJHZ20180418190529516, JSGG20180507183215520 Abstract This article introduces a simple wideband circularly polarized (CP) S-shaped slot antenna for ISM band wireless communication applications. By using a wide curve S-shaped slot patch on the top side and a T-shaped feeding line on the bottom side of the substrate, the wideband CP wave is generated. The overall size of the proposed antenna is 0.85λ × 0.85λ × 0.011λ (λ is the wavelength of the lowest operating frequency) and it has a broad impedance bandwidth of 68.1% between 1.66 and 3.44 GHz for S11 < –10 dB and a 3 dB axial-ratio bandwidth of 57.1% between 1.68 and 3.06 GHz. Within the axial-ratio bandwidth, the measured gain of the proposed antenna ranged from 2.1 to 5.4 dBic. The measured results are in good agreement with simulated results. The new type of slot antenna with wide bandwidth and simple structure is a good candidate for various RFID applications.

A High-Efficiency Broadband Rectenna for Ambient Wireless Energy Harvesting

Abstract: This paper presents a novel broadband rectenna for ambient wireless energy harvesting over the frequency band from 1.8 to 2.5 GHz. First of all, the characteristics of the ambient radio-frequency energy are studied. The results are then used to aid the design of a new rectenna. A novel two-branch impedance matching circuit is introduced to enhance the performance and efficiency of the rectenna at a relatively low ambient input power level. A novel broadband dual-polarized cross-dipole antenna is proposed which has embedded harmonic rejection property and can reject the second and third harmonics to further improve the rectenna efficiency. The measured power sensitivity of this design is down to $- {\bf 35}\;{\bf dBm}$ and the conversion efficiency reaches 55% when the input power to the rectifier is $- {\bf 10}\;{\bf dBm}$ . It is demonstrated that the output power from the proposed rectenna is higher than the other published designs with a similar antenna size under the same ambient condition. The proposed broadband rectenna could be used to power many low-power electronic devices and sensors and found a range of potential applications.

Crossed Dipole Loaded With Magneto-Electric Dipole for Wideband and Wide-Beam Circularly Polarized Radiation

Abstract: A crossed dipole that is loaded with a magneto-electric dipole to produce the wideband and wide-beam circularly polarized radiation characteristics is proposed. The crossed dipole is incorporated with double-printed vacant-quarter rings to feed the antenna. The antenna is backed by a metallic cavity to provide a unidirectional radiation pattern with a wide axial-ratio (AR) beamwidth and a high front-to-back ratio. Experimental results showed that the prototype with an overall size of $120\times 120\times30.5~\hbox{mm}^3$ has a $\vert { S}_{11}\vert bandwidth of 1.274–2.360 GHz and a 3-dB AR bandwidth of 1.39–1.82 GHz. The antenna showed a right-hand circular polarization (CP) radiation with a very wide 3-dB AR beamwidth ( $>165^{\circ}$ ) and a high radiation efficiency ( $ > 94\%$ ) within the operational bandwidth.

Crossed Dipole Antennas: A review.

Abstract: Crossed dipole antennas have been widely developed for current and future wireless communication systems. They can generate isotropic, omnidirectional, dual-polarized (DP), and circularly polarized (CP) radiation. Moreover, by incorporating a variety of primary radiation elements, they are suitable for single-band, multiband, and wideband operations. This article presents a review of the designs, characteristics, and applications of crossed dipole antennas along with the recent developments of single-feed CP configurations. The considerations of profile miniaturization, radiation pattern control, bandwidth enhancement, and multiband operation are emphasized.

Broadband Circularly Polarized Patch Antenna With Parasitic Strips

Abstract: A patch antenna with parasitic strips is presented for wideband circular polarization. In order to broaden the axial-ratio (AR) bandwidth of the original corner-truncated patch, four parasitic strips are sequentially rotated and gap-coupled around the patch. A capacitive-coupled feed with a small disc on the top of the feeding probe is utilized to obtain a wide impedance-matching bandwidth. Moreover, another disc-loaded shorting pin is placed at the center of the antenna to adjust the squint beams and improve the gains along $ + z$ -axis. Measured results show that the proposed antenna with a low profile of $0.13{\lambda _0}$ obtains a global bandwidth of 24% (2.32–2.95 GHz) for $\vert{S_{11}}\vert , ${\rm AR} , and average gain of 8 dBic.

Single-Feed Ultra-Wideband Circularly Polarized Antenna With Enhanced Front-to-Back Ratio

Abstract: This communication presents a single-feed ultra-wideband circularly polarized (CP) antenna with high front-to-back ratio (FBR). The antenna is composed of two orthogonally placed elliptical dipoles printed on both sides of a substrate. To realize high FBR, a novel composite cavity is also proposed and integrated with the presented crossed dipoles, which effectively reduces the backlobe of the crossed dipoles. Simulation results are in good agreement with the measured results that demonstrate an impedance bandwidth from 0.9 to 2.95 GHz (106.5%) and a 3-dB axial ratio (AR) bandwidth from 1 to 2.87 GHz (96.6%). The measured FBR is about 30 dB across the whole global navigation satellite system (GNSS) band. Compared with other reported single-feed wideband CP antennas, the antenna has advantages such as a wider CP bandwidth and lower backlobe radiation.