High Selectivity Passband Research Articles

A high-selective multiple-mode bandpass filter design, applicating in both millimeter-wave 5G and WiFi systems

This paper proposes a millimeter-wave bandpass filter (BPF) with high selectivity, which can be applied in both 5G and WiFi systems. Two dual-mode resonators (DMRs) are adopted and analyzed coupled microstrip lines (CMLs) and can form six transmission poles (TPs) and four transmission zeros (TZs). Furthermore, a multiple-mode resonator (MMR) is presented based on the DMRs to realize a high selective passband. Additionally, five extra TZs are introduced by two pairs of open-circuited stubs and transversal signal interference (TSI), which are introduced by cross-coupling of two signal paths. These TZs significantly enhance out-of-band suppression performance. The proposed BPF is fabricated in ceramic process, and measurement results demonstrate a minimum insertion loss of −1.52 dB, a 3-dB passband from 38.3 to 48.2 GHz, a 30-dB rectangular coefficient of 1.21, and a 30-dB stopband extending to the test limit of 67 GHz.

Impedance-Controllable Embedded Resonator for Switchable High-Selectivity Metamaterial Rasorber

A new technique for designing a dynamically controllable transparent window in the metamaterial absorber is investigated. Active lossy layer and lossless layer are proposed to establish the rasorber. First, the impedance-controllable embedded resonator is presented as a choke to limit the current flowing through the lossy elements. The interdigital and meander lines are applied to independently equivalent the large lumped capacitor and inductor required for low-frequency (L/S-band) resonance. It is demonstrated that the impedance loading of the inductive embedded resonator makes for a miniaturized unit size of 0.086 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda_{L}$</tex-math> </inline-formula> . Then, the cascaded embedded resonator on the lossless layer realizes a switchable high-selectivity passband in the reflection band. The transition from transmission band to absorption band is reduced due to the sharp roll-off edges of the passband. Finally, the rasorber prototype is fabricated and validated by the free-space measurement. By switching the bias of the p-i-n diodes, a high-selectivity window at 2.2 GHz can be triggered while it keeps absorbing in the whole band (1.2–3.7 GHz, 102%) at window-off state. Principles of operation and synthesis procedure are presented in this article.

Wideband High Selectivity Filter Chips With Adjustable Bandwidth Based on IPD Technology

In this brief, two kinds of wideband high selectivity passband filter chips with adjustable bandwidth are proposed. Independent controllable transmission zeros are introduced on both sides of the passband by LC resonators. Two designs are analyzed and calculated by means of odd-even mode analytical method and ABCD matrix to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> -parameters matrix method. Finally, integrated passive device (IPD) technology was used to process two versions of broadband and narrowband filters for each design, with a total number of four filter chips. The measured results show that 3-dB fractional bandwidth (FBW) of the first design are 19.3% and 83.6% respectively, which have verified a large degree of freedom in bandwidth control. In addition, the return loss of four chips is better than 17 dB, the optimal insertion loss ranges from 1.31 dB to 2.73 dB, and the stopband rejection is better than 25.2 dB, indicating excellent overall performance.

Stimulated Brillouin Scattering-Based Microwave Photonic Filter With a Narrow and High Selective Passband

In this paper, we present a microwave photonic filter bandpass filter with narrow bandwidth and high quality (Q) factor is presented which with a bandwidth of 7.8 MHz, a gain response of 24 dB, and Q factor is 2412. This performance is achieved through tailoring one Brillouin gain spectrum by two Brillouin loss spectrums. By precise control of the individual pump power and frequency, a narrowed bandpass filter is generated. We achieve this performance through the mathematical formulation of the Stimulated Brillouin scattering (SBS) spectrum relative frequency shift and SBS pumps power ratio, resulting in precise parameters resolution of the narrowest filter bandwidth leading to experimentally demonstration. We further show the variation trend of the filter bandwidth and gain response, leading to exploit the general discipline of this technology.

Dual-Mode Filtering Switches Based on Hybrid Microstrip-Cavity Structures

Dual-mode filtering switches using hybrid microstrip-cavity structures are proposed in this article. TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> modes of the cavity act as the resonant modes to obtain a dual-mode filtering response. The microstrip line integrating the control circuit is employed as the feeding network. In the ON-state, the diode of the control circuit is reverse biased. Based on the electromagnetic (EM) coupling theory, the two modes are excited to attain filtering performance, and the loss of the diode is significantly alleviated. When the diode is forward biased, the two modes are suppressed and isolation in the OFF-state is realized. Benefiting from the hybrid microstrip-cavity configuration, the coupling between source/load and resonator is flexible to control. Single-band and dual-band filtering switches are constructed. The dual-band filtering switch processes high selectivity passband response in the ON-state, the insertion losses are 0.4 dB, and three transmission zeros are distributed in the two bands. In the OFF-state, the isolations of the two bands are below 37 and 30.7 dB, respectively. Thus, the dual-mode filtering switches maintain high- Q features as the cavities. Moreover, they have multifunctionality and flexibility compared to the conventional cavity structures fed by probes and waveguides.

A miniaturized frequency selective rasorber with high selectivity passband and wideband absorption properties

A miniaturized frequency selective rasorber (FSR) with high selectivity passband and wideband absorption properties is presented. Its performance as an absorber over a wide absorption band from 8.08 to 18.08 GHz through the structure of metal incurved square loop structure loaded resistors. The frequency selective surface (FSS) using Jerusalem cross array and metallic patch realizes the transmission frequency band from 2.7 to 3.52 GHz. And the insertion loss (IL) is 0.37 dB at 3.08 GHz. The symmetry and miniaturized elements design enable the proposed FSR to achieve satisfactory incident angle stability. Its small unit size effectively avoids the generation of grating lobes in the absorption band and the interference to Radar Cross Section (RCS) reduction.

Dual-Mode Filtering Baluns Based on Hybrid Cavity-Microstrip Structures

Filtering baluns are proposed based on the hybrid cavity-microstrip structures in this article. The cavity acts as the resonator to obtain the filtering response. In the meanwhile, the microstrip feeding networks are used to excite multiple modes and achieve the balun characteristics simultaneously. The coupling mechanism between the slots and the cavities is utilized to analyze the single- and dual-band filtering baluns. Therefore, by combining the benefits of the cavities and the microstrip lines, multifunctional filtering baluns are realized. Besides, to reduce the volume and insertion loss further, a filtering balun based on the dielectric cavity-microstrip structure is presented and designed. It possesses high selectivity passband response, magnitude imbalance of 0.075 dB, and phase difference of 180° ± 0.2°. It is much smaller than that fed by the waveguide. On the other hand, it is easy to integrate with other components and robust in structure compared to that fed by the probe. Thus, the proposed hybrid structure not only maintains the high performance of the cavity but also has the flexibility of the planar circuit.

Fully Inkjet-Printed Dual-Mode Ring Bandpass Filter Using a Cross-Bridge Structure Embedded With a Metal–Insulator–Metal Capacitor

A fully inkjet-printed ring-resonator bandpass filter on a liquid crystal polymer was realized by using metal–insulator–metal (MIM) structures and via-hole interconnections. Two short stub feeding lines and a ring resonator were coupled using a cross-bridge structure embedded with an MIM capacitor to provide a high-selectivity passband, low insertion loss, and a more compact size. A stepped-impedance line was used as a perturbation to excite the dual mode of the ring resonator. Using the proposed method, a 29% fractional bandwidth was realized with four transmission zeros to improve the selectivity. In the passband, the minimal insertion loss and maximal return loss were −2.2 and −34.2 dB at 12.7 GHz, respectively. Fully inkjet-printed technology is recognized as a method of fabrication that results in a compact and low-cost 3-D integrated circuit package.

New Radiofrequency Exposure System with Real Telecommunication Signals

In recent years, there has been an increase in the number of studies on biological effects of Electromagnetic (EM) fields emitted from Base Transceiver Stations (BTSs). The biological effects of generated and real telecommunication signals produced by different types of exposure systems are discussed. However, the proper exposure methods for such experiments are very limited. We successfully developed a simple and cost-effective exposure unit with real GSM/DCS/UMTS signal from BTS containing proper modulations or intermittence (continuous, interrupted). Signal processing and conditioning unit is based on a Radiofrequency (RF) repeater. The downlink signal is filtered by integrated high selectivity passband filters and amplified to a required level. The main part of exposure unit is a Faraday cage with the specimen (exposure) area measuring 150 x 250 mm with E-field percent deviation less than 18%. This exposure system can be helpful in experiments with living organisms in in vivo studies and in vitro studies with normal or pathological cells and other micro scale structures being exposed to RF EM fields from BTS.

High selective frequency response in a complementary split ring resonator based transmission line

ABSTRACTIn this letter, a microstrip line based on complementary split ring resonator (CSRR) technology and coupled with square open‐loop resonator (OLR) is presented. The addition of OLR to the conventional CSRR‐loaded unit cell generates transmission zero in the upper stop band and improves the upper band rejection level without increasing the traversal dimensions. Consequently, a new high selective passband with increased bandwidth and a pair of transmission zeros at both lower and upper sides are formed due to the appropriate couplings among the resonators and the host microstrip line. Moreover, the geometry of the basic cell is quite simple without requiring complex configurations and via holes which is easy to fabricate and low in cost. For demonstration, a two‐stage transmission line prototype is fabricated and tested to experimentally validate the attractive out‐of‐band performance (&gt;36 dB) for filter applications as predicted in theory. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:12–15, 2017

HIGH SELECTIVITY DIFFERENTIAL BANDPASS FILTER USING DUAL-BEHAVIOR RESONATORS

A high selectivity differential bandpass filter (BPF) using two pairs of dual-behavior resonators (DBRs) is proposed in this letter. A high selectivity passband for the differential mode with second harmonic suppression is achieved, by utilizing shorted coupled lines with two short stubs. For the commonmode (CM) circuit, the CM responses can be suppressed over a wide frequency band by the loaded open/shorted stubs. To validate the feasibility of the proposed filter, a planar differential BPF (3-dB fractional bandwidth 4.9%) with good CM suppression is designed and fabricated. The theoretical and measured results agree well and show good in-band filtering performances and out-of- band harmonic suppression performances.

A NEW APPROACH OF DUAL-BAND FILTERS BY STEPPED IMPEDANCE SIMPLIFIED CASCADED QUADRUPLET RESONATORS WITH SLOT COUPLING

This paper presents novel approaches for dual-band bandpass filter design utilizing stepped impedance simplified cascaded quadruplet resonators (SI-SCQRs) with slot coupling. A pair of SISCQRs forms a cross coupled dual-band filtering path to provide high selectivity passband response, and a slot coupling structure provides SI-SCQRs with another filtering path for improving and controlling the performances of the dual-band filter such as insertion loss and bandwidth. Measured insertion losses are 0.26 dB and 1.2 dB, and return losses are better than 16.3 dB and 15.2 dB at the first and second Corresponding author: M.-P. Houng (mphoung@eembox.ncku.edu.tw).