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Now showing items 17 - 32 of 94

  • Compact Substrate Integrated Waveguide (SIW) Monopulse Network for Ku-Band Tracking System Applications

    Chen, Haidong   Che, Wenquan   He, Qingqiang   Feng, Wenjie   Wei, Xu   Wu, Ke  

    A compact single-layer substrate integrated wave-guide (SIW) monopulse network for Ku-band tracking system applications is investigated and demonstrated in this work. The feeding network and the monopulse comparator are integrated into a substrate with a structure size of 8.2 lambda(0) x 9 lambda(0) at center frequency while 32 output ports are welded perpendicularly for connecting active transmit/receive modules. The optimal design of a 3-dB coupler with metallic slots and phase shifter with dual steps is presented. The relative frequency bandwidth (vertical bar S11 vertical bar, vertical bar S22 vertical bar, and vertical bar S33 vertical bar < 10 dB) of the network is 6%, in which the phase imbalance of all ports is less than 5.5 degrees[root mean square (rms)], the power imbalance is about 0.5 dB (rms). The insertion losses are about 3-5 dB and the isolations between the three channels are all better than 25 dB. The good performances of this SIW-based monopulse network are validated by measurements, showing the advantages of low cost, light weight, easy fabrication, etc. It presents an excellent candidate for Ku-band tracking systems or up-band millimeter-wave systems.
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  • Microstrip Diplexer Design Using Open/Shorted Coupled Lines

    Feng, Wenjie   Hong, Meiling   Che, Wenquan  

    A novel microstrip diplexer with high selectivity and isolation performance is proposed through the combination of two compact bandpass filters composed of open/shorted lines and an open stub, which are designed for LTE application. Six transmission zeros in the upper stopband are used to suppress the harmonic of the microstrip diplexer. The transmission zeros near the passband can be adjusted conveniently by only changing the electrical length of the open/shorted stubs. A diplexer prototype with two passbands at 1.8 GHz and 2.1 GHz is fabricated. The isolation between the two channels is greater than 40 dB from 0.1 to 6.5 GHz.
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  • High-Selectivity Wideband Balanced Filters Using Coupled Lines With Open/Shorted Stubs

    Gao, Xin   Feng, Wenjie   Che, Wenquan  

    Two novel high-selectivity wideband balanced filters using symmetrical/asymmetrical coupled lines with open/shorted stubs are proposed in this letter. Multiple transmission zeros are achieved to obtain sharp rejection and good out-of-band suppression for the differential mode, in which fixed transmission zeros can be realized by half-wavelength open stubs and adjustable transmission zeros can be realized by loaded open/shorted coupled lines. In addition, all the transmission zeros can be allocated to suppress the common mode from 0 GHz to 3 f(0) (f(0) is the center frequency of the passband). Two balanced filters with 3-dB fractional bandwidths of 22% and 21% are, respectively, designed and fabricated.
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  • Microstrip dual-band bandstop filter of defected ground structure and stepped impedance resonators

    Che, Wenquan   Feng, Wenjie   Deng, Kuan  

    This article presents a compact microstrip dual-band bandstop filter (BSF), in which one g/4 defected ground structure (DGS) pair is utilised to realise one stopband while two stepped impedance resonators (SIRs) help obtain another stopband and suppress the spurious harmonics. The design strategies and the equivalent circuits are introduced in detail. The measured results indicate 43.8% and 18.7% fractional bandwidth in the two stopbands (2.4GHZ and 5.2GHz) respectively, and the return loss is greater than 15dB in the whole passband. In addition, size reduction can be conveniently achieved by adjusting the length of the SIRs and DGS.
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  • LTCC Multilayered Substrate-Integrated Waveguide Filter With Enhanced Frequency Selectivity for System-in-Package Applications

    Chin, Kuo-Sheng   Chang, Chih-Chun   Chen, Cheng-Hua   Guo, Zengxu   Wang, Desong   Che, Wenquan  

    This paper presents a cross-coupled bandpass filter with stacked substrate-integrated waveguide cavities on lowtemperature cofired ceramic substrates. The proposed filter has a local multipoint distribution service band with a novel sameside- feed input/output structure. Conventionally, a cross-coupled structure generates only a single pair of transmission zeros. The proposed filter can generate two pairs of transmission zeros beside the passband, thereby providing an excellent cutoff rate in the stopband and improved frequency selectivity. The additional pair of transmission zeros is created by the sameside- feed structure, which constructs an additional source-load coupling path without increasing the circuit size. A multipath coupling diagram is used to illustrate the conformation of the second pair of transmission zeros and predict its behavior. The experimental filter exhibits responses centered at 27.95 GHz with an insertion loss of -2.8 dB, and a bandwidth of 9%. Two pairs of transmission zeros ( at 26.3 and 29.6 GHz, and at 23.2 and 37 GHz) around the passband were obtained, achieving excellent selectivity and a wide stopband.
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  • Effect of cylinder spacing on reflection and propagation of substrate-integrated waveguide

    Wang, Lei   Che, Wenquan   Wang, Chao   Chang, Yumei   Wang, Zhanxian  

    The effects of cylinder spacing on the reflection and propagation of substrate-integrated waveguide (SIW) are investigated in this article. The reflection and propagation characteristics of SIW are simulated with HFSS in cases of different cylinder spacings. The simulation results show that, the cylinder spacing of SIW has much flexibility of selection, the return loss and insertion loss can be kept almost unchanged, provided that the cylinder spacings W
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  • A Novel Dual-Band Printed Monopole Antenna Based on Planar Inverted-Cone Antenna (PICA)

    Wang, Xia   Yu, Yang   Che, Wenquan  

    In this letter, a dual-band antenna based on planar inverted-cone antenna is proposed. Three pairs of slits are etched in the symmetrical circular arc sections of the inverted-cone-shaped structure to achieve the purpose of size reduction and dual-band performance. The frequency ratio and impedance matching can be adjusted flexibly by changing the parameters of the slits. The proposed antenna covers two relative impedance bandwidths of 26.5% and 12.3% with corresponding frequency bands 0.95-1.24 and 2.14-2.42 GHz, respectively.
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  • Tunable Dual-Band Filter and Diplexer Based on Folded Open Loop Ring Resonators

    Feng, Weijie   Zhang, Ying   Che, Wenquan  

    Tunable dual-band filter and diplexer based on folded open loop ring resonators (OLRRs) are proposed in this brief. Two pairs of OLRRs of different center frequencies are utilized to couple with microstrip transmission lines in these two devices, and there is no extra matching network in the diplexer structure. Maximal magnetic coupling and high isolation can be obtained by placing the resonators at proper positions along the feeding lines. The passband/channel frequencies of the dual-band filter/diplexer can be tuned independently by varying dc bias voltages applied to the varactors loaded at one end of the resonators. In addition, a broad harmonic suppression can be obtained by choosing appropriate lumped elements adding to the OLRRs. The performances of the proposed devices can be verified by the simulated and measured results.
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  • Compact Pattern-Reconfigurable Monopole Antenna Using Parasitic Strips

    Juan, Yue   Che, Wenquan   Yang, Wanchen   Chen, Zhi Ning  

    A monopole antenna array with pairs of switchable parasitic strips is proposed to realize eight beams for azimuth omnidirectional coverage. The proposed antenna consists of one active monopole and four pairs of parasitic elements. Each pair of parasitic elements is formed by two switchable parasitic strips. By switching p-i-n diodes, a pair of parasitic strips can be used as a director or a reflector. By introducing a shorter parasitic strip between the monopole and the longer strip, the radiation impedance of the monopole is increased when the monopole and the reflector/director are closely positioned. As a result, the diameter of the whole antenna array is only 0.1 lambda(0), where lambda(0) is the operating wavelength in free space. For demonstration, the antenna is designed to realize eight beams in the azimuth plane with a 45 degrees-angle interval at 1.575 GHz for global positioning service with the peak gain of all the beams larger than 7 dBi at the elevation angle of 60 degrees.
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  • High Selectivity Wideband Balanced Filters With Multiple Transmission Zeros

    Feng, Wenjie   Gao, Xin   Che, Wenquan   Yang, Wanchen   Xue, Quan  

    Two novel high selectivity wideband balanced filters based on open/shorted stubs with multiple transmission zeros are proposed in this brief. Two and four transmission zeros near each passband for the differential mode (DM) can be easily achieved for two balanced filters. In addition, the common mode can be suppressed with three and five transmission zeros with an insertion loss greater than 15 dB/20 dB over a wide frequency band. Two prototypes with 3-dB fractional bandwidths of 67.6% and 37.8% for the DM with an insertion loss greater than 15 dB (7.0-12.7 GHz) are designed and fabricated. A good agreement can be observed between the measured results and the theoretical expectations.
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  • A Novel UWB Antenna With Dual Notched Bands for WiMAX and WLAN Applications

    Jiang, Wen   Che, Wenquan  

    A novel planar ultrawideband (UWB) antenna with dual notched bands is proposed and investigated. The antenna consists of a square patch and a modified grounded plane. To realize dual notched bands characteristics, a T-shaped stub embedded in the square slot of the radiation patch and a pair of U-shaped parasitic strips beside the feed line is used. The advantage of this antenna is the high rejection level in the stopband. The measured results show that the proposed dual-notched-bands planar antenna shows a very wide bandwidth from 2.8 to 11.0 GHz defined by voltage standing wave ratio, VSWR < 2, with two notched bands of 3.3-4.0 GHz (WiMAX band) and 5.05-5.90 GHz (WLAN band), respectively. Both the experimental and simulated results of the proposed antenna are presented, indicating that the antenna is a good candidate for various UWB applications.
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  • Analytical Design of Compact Dual-Band Filters Using Dual Composite Right-/Left-Handed Resonators

    Shen, Guangxu   Che, Wenquan   Feng, Wenjie   Xue, Quan  

    A new kind of compact dual-mode dual-composite right-/left-handed resonators is proposed. Dual-band bandpass filters (BPFs) are consequently designed with over 88% size reduction. To assist the filter design, an analytical design method is further presented, with which one filter can be designed flexibly according to the desired frequencies and bandwidths (BWs). To alleviate the design difficulties, a synthesis design technique and a feedback-based optimization process are both employed. In addition, the independent control of frequencies, BWs, and coupling coefficients are also realized, which provide large freedom for designing BPFs. To ensure the feasibility of the design method, the valid ranges of center frequency and BW ratios are first determined. Furthermore, four compact BPFs are designed with a large/small center frequency ratio (3.11/1.6) and a large/small BW ratio (2.52/0.52). Good agreement between the measurements and simulations are observed, indicating the validity of the proposed design method.
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  • A Novel Hybrid Method for Estimating Channel Temperature and Extracting the AlGaN/GaN HEMTs Model Parameters

    Zhang, Mi   Che, Wenquan   Ma, Kaixue  

    A new hybrid method for estimating channel temperature and extracting the AlGaN/GaN high electron mobility transistors (HEMTs) model parameters is proposed in this paper. The method studies the temperature-dependent feature of access resistances and estimates the channel temperature of tested device by using a novel scanning channel temperature optimization approach. For the first time, the relationship between thermal resistance (R-th) and bias voltage is used to ensure the accuracy of the HEMT device model. The estimated channel temperatures are experimentally verified by using the Raman spectroscopy method. For different sizes of the AlGaN/GaN HEMT device, the simulation results based on the proposed model are compared with the conventional model as well as the commercial model, a better agreement with the measurement data for the proposed method is achieved.
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  • Wideband power dividers with improved upper stopband using coupled lines

    Feng, Wenjie   Zhao, Chaoying   Ma, Xueke   Che, Wenquan  

    Three novel wideband microstrip power dividers with improved upper stopband using coupled lines are proposed in this study. Wide upper stopband can be obtained by the multiple transmission zeros realised by the stepped coupled lines. Isolation resistors are proposed to achieve wideband power division isolation for the power dividers. Three wideband microstrip power dividers with division bandwidths of 47% (1.76-2.84 GHz), 47% (1.75-2.83 GHz), and 47.8% (1.75-2.85 GHz) are designed and fabricated. The upper stopband for the last two power dividers can be extended up to five and six octaves.
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  • Wireless Power Transfer With Three-Ports Networks:Optimal Analytical Solutions

    Monti, Giuseppina   Che, Wenquan   Wang, Qinghua   Costanzo, Alessandra   Dionigi, Marco   Mastri, Franco   Mongiardo, Mauro   Perfetti, Renzo   Tarricone, Luciano   Chang, Yumei  

    A wireless transfer link between three magnetically coupled resonators has been considered. Two different configurations have been investigated. In one case a single transmitter and two receivers are present. In the other case two transmitters and a single receiver are employed. For each case optimal analytical solutions for the load values that maximize the power delivered to the load(s) and the efficiency have been found and validated by comparisons with circuit simulations.
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  • Formula Derivation and Verification of Characteristic Impedance for Offset Double-Sided Parallel Strip Line (DSPSL)

    Che, Wenquan   Gu, Liming   Chow, Y. L.  

    Double-sided parallel strip line (DSPSL) is a versatile microwave transmission line. With an offset, it allows for large variations of the characteristic impedance and therefore flexibility for the design of novel microwave devices. In this letter, a formula for the characteristic impedance of DSPSL is derived by the fuzzy EM method and verified by commercial software. Very good agreement is observed.
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