Author
Wenjie Feng
Other affiliations: Nanjing University of Information Science and Technology, Nanjing University, South China University of Technology ...read more
Bio: Wenjie Feng is an academic researcher from Nanjing University of Science and Technology. The author has contributed to research in topics: Band-pass filter & Passband. The author has an hindex of 27, co-authored 280 publications receiving 2638 citations. Previous affiliations of Wenjie Feng include Nanjing University of Information Science and Technology & Nanjing University.
Topics: Band-pass filter, Passband, Wideband, Microstrip, Stopband
Papers
More filters
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TL;DR: In this paper, two novel wideband differential bandpass filters based on a T-shaped structure are proposed, and two prototypes with 3-dB fractional bandwidth of 70% and 70.7% for the differential mode and insertion loss greater than 13.5 dB for common mode (0-19 GHz).
Abstract: Two novel wideband differential bandpass filters based on a T-shaped structure are proposed in this paper. Broad passband and wideband harmonic suppression for the differential/common mode can be easily achieved for the wideband differential filter without cross coupling, due to the controlled resonator frequencies of the shorted/open T-shaped structure. In addition, another more compact differential filter using cross coupling is proposed with two transmission zeros close to the passband to improve the selectivity for the differential mode. To verify the presented concept, two prototypes (er = 2.65, h = 0.5 mm) with 3-dB fractional bandwidth of 70% and 70.7% for the differential mode and insertion loss greater than 13.5 dB for common mode (0-19 GHz) are designed and fabricated. Good agreement can be observed between measured results and theoretical expectations.
146 citations
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TL;DR: In this paper, a novel filtering method based on the metasurface antenna (MSA) with radiation nulls is proposed without loading extra circuits, which can achieve the wideband filtering response in a low profile, as well as high gain with high aperture efficiency.
Abstract: A novel filtering method based on the metasurface antenna (MSA) with radiation nulls is proposed without loading extra circuits. Due to the specific multiunit structure of MSA, the filtering method is first realized on each radiating metasurface (MS) unit by introducing a multifolded U-shaped slot and a defected ground structure to generate lower edge radiation nulls. Meanwhile, coplanar parasitic patches are loaded around the MS units to provide upper edge nulls and simultaneously introduce extra in-band resonances for wide passband. Thus, a low-profile, wideband, and high-gain filtering antenna is readily constructed. To verify the concept, a prototype with a low profile of only $0.04\lambda _{{0}}$ is designed and fabricated. The simulated and measured results agree well, demonstrating a good performance with large impedance bandwidth of about 20%, high average gain of 8 dBi, and high aperture efficiency of about 90%, together with high out-of-band suppression levels of about 20 dB. In addition, the radiation patterns are symmetric in both the E- and H-planes with cross-polarization suppressions of over 20 dB. Compared with the reported filtering antennas, the proposed filtering MSA can achieve the wideband filtering response in a low profile, as well as high gain with high aperture efficiency.
117 citations
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TL;DR: In this article, the authors proposed that the differential mode should have excellent out-of-band rejection and high selectivity for the desired frequency band, while the common mode should be suppressed over a wider frequency band.
Abstract: With the development of wireless communication technology, radiofrequency (RF) circuits and integrated circuits are becoming more complex and packing more functionality and signals into an ever closer space, with a high level of electromagnetic interaction between circuit nodes and interference/crosstalk from substrate coupling and free space [1]. Balanced/differential circuit technology has become more important in modern communication systems because of good commonmode rejection that leads to relatively high immunity to environmental noise when compared with the single-ended technology [1]-[3], as shown in Figure 1(a) and (b). For balanced circuits, the differential mode should have excellent out-of-band rejection and high selectivity for the desired frequency band, while the common mode should be suppressed over a wider frequency band. In the past few years, many microstrip balanced filters for single band and dual band with common-mode suppression have been realized [4]-[10], with different balanced networks, balanced driven antennas, balanced amplifiers, and mixers [11]-[18].
93 citations
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TL;DR: Two novel balanced filters with wideband common mode suppression using dual-mode ring resonators with good in-band filtering performance and high selectivity are proposed in this paper.
Abstract: Two novel balanced filters with wideband common mode suppression using dual-mode ring resonators are proposed in this paper. Two and four transmission zeros close to the passband are realized to improve the selectivity for the differential mode. In addition, over 20-dB common mode suppression can be realized from 0 GHz to $5f_{0}$ ( $f_{0}$ is the center frequency of the passband), due to the all-stop transmission characteristic of the open/shorted coupled lines. To verify the presented concepts, two prototypes ( $\varepsilon_{r}=2.65$ , $h=1.0\ {\rm mm}$ ) with 3-dB fractional bandwidths of 22.9% and 21.9% for the differential mode are designed and fabricated. The theoretical and measured results agree well and show good in-band filtering performance and high selectivity.
92 citations
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TL;DR: Three novel wideband balanced-to-unbalanced filtering power dividers based on coupled lines based on coupling lines are proposed in this paper and show good performances for differential-mode out-of-band suppression, common-mode suppression, and isolation.
Abstract: Three novel wideband balanced-to-unbalanced filtering power dividers based on coupled lines are proposed in this paper. Multifunctional power dividers can replace various cascaded single devices to decrease integration mismatching loss and circuit size. The wideband response can be easily realized by the coupled lines structures. To further improve the differential-mode passband selectivity, open/shorted coupled lines and half-wavelength open stubs are applied to introduce two transmission zeros near the passband, respectively. In addition, a resistor in the middle of two single-ended ports can be used to realize isolation between out ports. To verify the proposed concepts, three prototypes of wideband balanced-to-unbalanced filtering power dividers operating at 2 GHz are designed and fabricated with the 4-dB differential-mode bandwidths of 80.5%, 71.5%, and 80%. All the structures show good performances for differential-mode out-of-band suppression, common-mode suppression, and isolation.
84 citations
Cited by
More filters
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685 citations
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08 Dec 1998TL;DR: In this article, the authors consider the unique features of UWB technology and propose that the FCC should consider them in considering changes to Part 15 and take into account their unique features for radar and communications uses.
Abstract: In general, Micropower Impulse Radar (MIR) depends on Ultra-Wideband (UWB) transmission systems. UWB technology can supply innovative new systems and products that have an obvious value for radar and communications uses. Important applications include bridge-deck inspection systems, ground penetrating radar, mine detection, and precise distance resolution for such things as liquid level measurement. Most of these UWB inspection and measurement methods have some unique qualities, which need to be pursued. Therefore, in considering changes to Part 15 the FCC needs to take into account the unique features of UWB technology. MIR is applicable to two general types of UWB systems: radar systems and communications systems. Currently LLNL and its licensees are focusing on radar or radar type systems. LLNL is evaluating MIR for specialized communication systems. MIR is a relatively low power technology. Therefore, MIR systems seem to have a low potential for causing harmful interference to other users of the spectrum since the transmitted signal is spread over a wide bandwidth, which results in a relatively low spectral power density.
644 citations
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TL;DR: In this paper, two novel wideband differential bandpass filters based on a T-shaped structure are proposed, and two prototypes with 3-dB fractional bandwidth of 70% and 70.7% for the differential mode and insertion loss greater than 13.5 dB for common mode (0-19 GHz).
Abstract: Two novel wideband differential bandpass filters based on a T-shaped structure are proposed in this paper. Broad passband and wideband harmonic suppression for the differential/common mode can be easily achieved for the wideband differential filter without cross coupling, due to the controlled resonator frequencies of the shorted/open T-shaped structure. In addition, another more compact differential filter using cross coupling is proposed with two transmission zeros close to the passband to improve the selectivity for the differential mode. To verify the presented concept, two prototypes (er = 2.65, h = 0.5 mm) with 3-dB fractional bandwidth of 70% and 70.7% for the differential mode and insertion loss greater than 13.5 dB for common mode (0-19 GHz) are designed and fabricated. Good agreement can be observed between measured results and theoretical expectations.
146 citations
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TL;DR: The proposed multi-dipole antenna with switchable 0°, +45°, 90° and −45° linear polarizations is able to overcome the polarization mismatching and multi-path distortion in complex wireless channels as in BWCS.
Abstract: This paper presents a multi-polarization reconfigurable antenna with four dipole radiators for biomedical applications in body-centric wireless communication system (BWCS). The proposed multi-dipole antenna with switchable 0°, +45°, 90° and −45° linear polarizations is able to overcome the polarization mismatching and multi-path distortion in complex wireless channels as in BWCS. To realize this reconfigurable feature for the first time among all the reported antenna designs, we assembled four dipoles together with 45° rotated sequential arrangements. These dipoles are excited by the same feeding source provided by a ground tapered Balun. A metallic reflector is placed below the dipoles to generate a broadside radiation. By introducing eight PIN diodes as RF switches between the excitation source and the four dipoles, we can control a specific dipole to operate. As the results, 0°, +45°, 90° and −45° linear polarizations can be switched correspondingly to different operating dipoles. Experimental results agree with the simulation and show that the proposed antenna well works in all polarization modes with desirable electrical characteristics. The antenna has a wide impedance bandwidth of 34% from 2.2 to 3.1 GHz (for the reflection coefficient ${\leq}$ −10 dB) and exhibits a stable cardioid-shaped radiation pattern across the operating bandwidth with a peak gain of 5.2 dBi. To validate the effectiveness of the multi-dipole antenna for biomedical applications, we also designed a meandered PIFA as the implantable antenna. Finally, the communication link measurement shows that our proposed antenna is able to minimize the polarization mismatching and maintains the optimal communication link thanks to its polarization reconfigurability.
117 citations
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TL;DR: In this article, two planar efficient wideband electrically small monopole filtennas are presented, one directly evolved from a common planar capacitively loaded loop (CLL)-based filter and the other consisting of a driven element augmented with a CLL structure and slots etched into its ground plane.
Abstract: Two planar efficient wideband electrically small monopole filtennas are presented. The first one directly evolved from a common planar capacitively loaded loop (CLL)-based filter. This filtenna possesses a flat realized gain response within the operational band and good band-edge selectivity. The second filtenna consists of a driven element augmented with a CLL structure and with slots etched into its ground plane. It expands the fractional impedance bandwidth of the first case from 6.28% up to 7.9%. It too has a gain response that remains flat over its operational bandwidth and even higher band-edge selectivity. Both filtennas are electrically small: $ka . The experimental results, which are in good agreement with their simulated values, demonstrate that both filtennas exhibit excellent impedance matching, high radiation efficiency, flat gain response, and steep skirts at both band edges, as well as producing monopole radiation patterns that are uniform and nearly omnidirectional in their H-planes.
95 citations