Wen Jun Li

Bio: Wen Jun Li is an academic researcher from Hangzhou Dianzi University. The author has contributed to research in topics: Slot antenna & Antenna efficiency. The author has an hindex of 4, co-authored 4 publications receiving 248 citations.

Bandwidth-Enhanced Low-Profile Cavity-Backed Slot Antenna by Using Hybrid SIW Cavity Modes

Abstract: A bandwidth enhanced method of a low-profile substrate integrated waveguide (SIW) cavity-backed slot antenna is presented in this paper. Bandwidth enhancement is achieved by simultaneously exciting two hybrid modes in the SIW-backed cavity and merging them within the required frequency range. These two hybrid modes, whose dominant fields are located in different half parts of the SIW cavity, are two different combinations of the and resonances. This design method has been validated by experiments. Compared with those of a previously presented SIW cavity-backed slot antenna, fractional impedance bandwidth of the proposed antenna is enhanced from 1.4% to 6.3%, its gain and radiation efficiency are also slightly improved to 6.0 dBi and 90%, and its SIW cavity size is reduced about 30%. The proposed antenna exhibits low cross polarization level and high front to back ratio. It still retains advantages of low-profile, low fabrication cost, and easy integration with planar circuits.

A Gain Enhanced Cavity Backed Slot Antenna using High Order Cavity Resonance

Abstract: A gain enhanced method of substrate integrated waveguide (SIW) cavity backed slot antenna by using a high order cavity resonance has been presented in this paper. When the TE220 resonance is excited in the SIW cavity, a high gain radiation with the gain of 8.1 dBi can be achieved, which is about 2.7 dB higher than that of the previously presented SIW cavity backed slot antenna by using the TE120 or TE210 resonance. This design method can be extended to using the higher order cavity resonances such as TE230, TE330 and TE440 etc. to get a much higher gain radiation. Compared with an antenna array which has the same gain, the proposed antenna has advantages of simple feed network and more compact size.

Cavity backed dual slot antenna for gain improvement

Abstract: A simple method of gain improvement for the cavity backed slot antenna based on the substrate integrated waveguide technique has been presented in this article. By using dual slot at the cavity edges to substitute a single slot at the cavity center as the radiating element, gain of the cavity backed slot antenna has been improved about 1.7 dB whereas its total size is little reduced. The proposed antenna has high radiation performance and keeps the advantages low profile, easy integration, and low cost fabrication. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2767–2769, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25582

A 2∗2 antenna array consisting of low profile cavity backed slot antennas

Abstract: A 2∗2 antenna array constructed by using a new substrate integrated waveguide (SIW) cavity-backed slot antenna as its single element is proposed in this paper. Comparing to that of a single antenna element, the antenna array gain has been improved of 5.8 dB. The proposed antenna array has a lot of advantages, such as low profile, light weight, easy fabrication with low cost and convenient integration with planar circuit, due to using SIW structure.

Compact Half Diamond Dual-Band Textile HMSIW On-Body Antenna

Abstract: A novel wearable dual-band textile antenna, designed for optimal on-body performance in the 2.4 and 5.8 GHz Industrial, Scientific and Medical bands, is proposed. By using brass eye-lets and a combination of conducting and non-conductive textile materials, a half-mode substrate integrated waveguide cavity with ground plane is realized that is very compact and flexible, while still directing radiation away from the wearer. Additional miniaturization is achieved by adding a row of shorting vias and slots. Beside excellent free space performance in the 2.4 and 5.8 GHz bands, respectively, with measured impedance bandwidth of 4.9% and 5.1%, maximal measured free-space gain of 4.1 and 5.8 dBi, and efficiency of 72.8% and 85.6%, very stable on-body performance is obtained, with minimal frequency detuning when deploying the antenna on the human body and when bent around cylinders with radii of 75 and 40 mm. At 2.45 and 5.8 GHz, respectively, the measured on-body gain is 4.4 and 5.7 dBi, with sufficiently small calculated SAR values of 0.55 and 0.90 W/kg. These properties make the proposed antenna excellently suited for wearable on-body systems.

Enhanced Isolation of a Closely Spaced Four-Element MIMO Antenna System Using Metamaterial Mushroom

Abstract: A double-layer mushroom structure is proposed to enhance the interelement isolation of a four-element antenna system, wherein four closely positioned substrate-integrated cavity-backed slot (SICBS) antenna elements are configured for multiple-input multiple-output (MIMO) applications. A wall with a double-layer mushroom structure is positioned in between the four antenna elements. An antenna prototype with a ground plane size of ${\mathbf{0}}.{\mathbf{96}}\;{{\mathbf{\lambda }}_{\mathbf{0}}} \times 0.96\;{{\mathbf{\lambda }}_{\mathbf{0}}}$ ( ${{\mathbf{\lambda }}_{\mathbf{0}}}$ is the free space-wavelength at 2.4 GHz) demonstrates an enhanced interelement isolation of 16 dB for parallel-directed antenna element pairs, while the isolation of the orthogonally directed antenna element pairs remains unchanged over the operating bandwidth ( $\vert {{\mathbf{S}}_{{\mathbf{11}}}}\vert ) of 2.396 –2.45 GHz. With the enhanced isolation larger than 42 dB between each antenna element pair, the envelope correlation coefficient (ECC) is lower than 0.02 across the operating bandwidth. The simulated and measured results validate the good MIMO diversity performance of the proposed antenna system.

Broadband Substrate Integrated Waveguide Cavity-Backed Bow-Tie Slot Antenna

Abstract: A novel design technique for broadband substrate integrated waveguide cavity-backed slot antenna is demonstrated in this letter. Instead of using a conventional narrow rectangular slot, a bow-tie-shaped slot is implemented to get broader bandwidth performance. The modification of the slot shape helps to induce strong loading effect in the cavity and generates two closely spaced hybrid modes that help to get a broadband response. The slot antenna incorporates thin cavity backing (height <;0.03λ 0 ) in a single substrate and thus retains low-profile planar configuration while showing unidirectional radiation characteristics with moderate gain. A fabricated prototype is also presented that shows a bandwidth of 1.03 GHz (9.4%), a gain of 3.7 dBi over the bandwidth, 15 dB front-to-back ratio, and cross-polarization level below -18 dB.

Wearable Textile Half-Mode Substrate-Integrated Cavity Antenna Using Embroidered Vias

Abstract: A wearable textile antenna based on the fundamental mode of a half-mode substrate-integrated semicircular cavity is presented. The antenna operates around 5 GHz and is manufactured with two layers of silver fabric conductors, on the top and bottom of a low-permittivity low-loss foam with minimal water absorption. The vias are realized with five passes of conductive yarn with a diameter of 0.12 mm placed every 1 mm. Their precise arrangement is obtained using computerized embroidery. Compared to other antenna concepts, this design features minimal manufacturing complexity as it does not require accurate patterned cutting of textile conductors. Good isolation from the human body and robustness in terms of deformation are further key characteristics of this structure. This letter provides design guidelines and investigates realistic issues associated with the manufacturing technique. A good agreement between simulated and measured performance with a gain of 7.2 dB validates the concept.

Design and Analysis of SIW Cavity Backed Dual-Band Antennas With a Dual-Mode Triangular-Ring Slot

Abstract: Substrate integrated waveguide (SIW) cavity backed dual-band triangular-ring slot (TRS) antennas are proposed for planar integration. First, a low profile dual band 45 ° linearly polarized (LP) antenna is designed and analyzed. The dual-mode TRS is proposed and developed by simultaneously exciting the mode of the slot and the mode of the patch inside the slot. To minimize the antenna size, the lowest mode (TE110 mode) of the SIW cavity is adopted to excite the TRS. The -10 dB impedance bandwidth at the higher band is 5.9%, 58.3% wider than that of the conventional SIW cavity backed slot antenna. The interactions of the SIW cavity, the slot mode and the patch mode are analyzed with circuit models and verified by full wave simulations, which provides a new insight into the SIW cavity backed antennas. Then, by exciting a pair of the 45° LP antennas with an SIW coupler, a circularly polarized (CP) dual band antenna with a small frequency ratio of 1.26 is developed. The two antennas are fabricated and tested, and the measured and simulated results agree well.