scholarly journals Series-connected array of superconductor–insulator–superconductor junctions in the 100 GHz-band heterodyne mixer for FOREST on the Nobeyama 45 m telescope

2018 ◽  
Vol 71 (Supplement_1) ◽  
Author(s):  
Taku Nakajima ◽  
Hirofumi Inoue ◽  
Yumi Fujii ◽  
Chieko Miyazawa ◽  
Hiroyuki Iwashita ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Quartz Substrate ◽  
Impedance Matching ◽  
Characteristic Impedance ◽  
Noise Temperature ◽  
Coupling Efficiency ◽  
Wide Frequency Range ◽  
Quantum Limit ◽  
Receiver Noise ◽  
Sis Junction

Abstract We have designed and experimentally evaluated a series-connected array of superconductor–insulator–superconductor (SIS) junctions in the 100 GHz-band mixer for the multi-beam receiver FOREST on the Nobeyama 45 m millimeter-wave telescope. The construction of the junction chip comprised a waveguide probe antenna, impedance-matching circuit, SIS array junction, and choke filter, which were made from a superconducting niobium planar circuit on a quartz substrate. The multi-stage impedance-matching circuit between the feed point and the SIS junction was designed as a capacitively loaded transmission line, and it comprised two sections with high (∼90 Ω) and low (∼10 Ω) characteristic impedance transmission lines. The structure of this tuning line was simple and easy to fabricate, and the feed impedance matched with the SIS junction in a wide frequency range. The signal coupling efficiency was more than 92% and the expected receiver noise temperature was approximately twice the quantum limit for 75–125 GHz based on quantum theory. The array junction devices with three to six connected junctions were fabricated and we measured their performance in terms of the receiver noise temperature and gain compression in the laboratory. We successfully developed an array junction device with a receiver noise temperature of ∼15–30 K and confirmed that the improvement in the saturation power corresponded to the number of junctions. The newly developed array junction mixer was installed in the FOREST receiver and it successfully detected the 12CO(J = 1–0) molecular line toward IRC +10216 with the Nobeyama 45 m telescope.

scholarly journals Split striplines with adjustable parameters and devices based on them

2019 ◽  
Vol 30 ◽  
pp. 06015
Author(s):  
Nickolay Malyutin ◽  
Alexandra Malyutina ◽  
Georgiy Malyutin ◽  
Alexander Zabolotsky
Keyword(s):  
Frequency Analysis ◽  
Transmission Lines ◽  
Electromagnetic Coupling ◽  
Characteristic Impedance ◽  
Scattering Matrix ◽  
Wide Frequency Range ◽  
Strip Line ◽  
Frequency Range ◽  
Strip Lines

The split strip lines (SSL) with adjustable parameters and examples of devices based on them are examined. Changing the parameters of the split strip lines are carried out with the help of so-called controlling strips, coupled with parts of the split strip line and having a strong electromagnetic coupling with them. Between controlling strips and the screen the lumped regulating elements are included. In wide frequency range such strip structures can be considered as transmission lines with changeable characteristic impedance and changeable propagation coefficient. Frequency analysis of of scattering matrix S of controlled split strip lines with different circuits of strip inclusion is carried out. Examples of the use of split strip lines with adjustable parameters in the design of different devices were discussed.

scholarly journals Compact Liquid Crystal Based Tunable Band-Stop Filter with an Ultra-Wide Stopband by Using Wave Interference Technique

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Longzhu Cai ◽  
Huan Xu ◽  
Daping Chu
Keyword(s):  
Liquid Crystal ◽  
Impedance Matching ◽  
Wide Frequency Range ◽  
Ultra Wideband ◽  
New Wave ◽  
Wave Interference ◽  
Rejection Level ◽  
Band Stop Filter ◽  
The Individual ◽  
Uwb Applications

A wave interference filtering section that consists of three stubs of different lengths, each with an individual stopband of its own central frequency, is reported here for the design of band-stop filters (BSFs) with ultra-wide and sharp stopbands as well as large attenuation characteristics. The superposition of the individual stopbands provides the coverage over an ultra-wide frequency range. Equations and guidelines are presented for the application of a new wave interference technique to adjust the rejection level and width of its stopband. Based on that, an electrically tunable ultra-wide stopband BSF using a liquid crystal (LC) material for ultra-wideband (UWB) applications is designed. Careful treatment of the bent stubs, including impedance matching of the main microstrip line and bent stubs together with that of the SMA connectors and impedance adaptors, was carried out for the compactness and minimum insertion and reflection losses. The experimental results of the fabricated device agree very well with that of the simulation. The centre rejection frequency as measured can be tuned between 4.434 and 4.814 GHz when a biased voltage of 0–20 Vrms is used. The 3 dB and 25 dB stopband bandwidths were 4.86 GHz and 2.51 GHz, respectively, which are larger than that of other recently reported LC based tunable BSFs.

Analysis of Characteristic of Microstrip Signal Loss in Course of Signal Transmission

2011 ◽  
Vol 194-196 ◽  
pp. 2229-2232
Author(s):  
Qing Song Xiong ◽  
Zhao Hua Wu ◽  
Pin Chen ◽  
Sheng Zhang
Keyword(s):  
Line Width ◽  
Transmission Lines ◽  
Coupling Effect ◽  
Signal Transmission ◽  
Characteristic Impedance ◽  
Signal Loss ◽  
Scattering Parameters ◽  
Scattering Parameter ◽  
Conductor Loss ◽  
Strip Lines

The effect of loss of transmission line on the transmission signal can’t be ignored in microwave circuits. Based on the theory of loss and microwave network principle, the effect of the width, parallel length and space of transmission lines on the scattering parameters’ insertion loss is analyzed in perspective of scattering parameters of the odd mode and even mode. The simulation results show that: when the other parameters are fixed, both the characteristic impedance and the conductor loss decrease non-linearly with the line width broadening; due to the coupling effect between micro-strip lines, the first trough frequency of the scattering parameter S21 curved line, that is the point the signal energy attenuate most seriously, decreases linearly with line width broadening and increases non- linearly with line spaces broadening.

scholarly journals Flexible Broadband Metamaterial Perfect Absorber Based on Graphene-Conductive Inks

Photonics ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 440
Author(s):  
Le Van Long ◽  
Nguyen Sy Khiem ◽  
Bui Son Tung ◽  
Nguyen Thanh Tung ◽  
Trinh Thi Giang ◽  
...  
Keyword(s):  
Impedance Matching ◽  
Optical Filters ◽  
Wide Frequency Range ◽  
Absorption Feature ◽  
Perfect Absorber ◽  
Frequency Range ◽  
Absorption Mechanism ◽  
Polarization Insensitive ◽  
Metamaterial Perfect Absorber ◽  
High Absorption

In this work, we proposed a flexible broadband metamaterial perfect absorber (FBMPA) by exploiting a pasted conductive-graphene ink on a polyimide substrate. For the flat FBMPA, an absorption over 90% was found to cover a wide frequency range (from 7.88 to 18.01 GHz). The high-absorption feature was polarization-insensitive and regarded as stable with respect to the oblique incidence up to 30 degrees of electromagnetic wave. The high absorption was maintained well even when the absorber was wrapped. That is, the FBMPA was attached to cylindrical surfaces (with the varying radius from 4 to 50 cm). For both flat and curved states, the absorption mechanism was explained by the perfect impedance matching and the dielectric loss of the proposed absorber. Our work provides the groundwork for the commercialization of future meta-devices such as sensors, optical filters/switchers, photodetectors, and energy converters.

scholarly journals A Novel Synthetization Approach for Multi Coupled Line Section Impedance Transformers in Wideband Applications

2022 ◽  
Vol 12 (2) ◽  
pp. 875
Author(s):  
Nan Zhang ◽  
Xiaolong Wang ◽  
Chunxi Bao ◽  
Bin Wu ◽  
Chun-Ping Chen ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Return Loss ◽  
Circuit Simulation ◽  
Characteristic Impedance ◽  
Fractional Bandwidth ◽  
Coupled Line ◽  
Variable Parameters ◽  
Line Section ◽  
Original Topology ◽  
Impedance Parameters

In this paper, a novel synthetization approach is proposed for filter-integrated wideband impedance transformers (ITs). The original topology consists of N cascaded coupled line sections (CLSs) with 2N characteristic impedance parameters. By analyzing these characteristic impedances, a Chebyshev response can be derived to consume N + 2 design conditions. To optimize the left N − 2 variable parameters, CLSs were newly substituted by transmission lines (TLs) to consume the remaining variable parameters and simplify the circuit topology. Therefore, there are totally 2N − N − 2 substituting possibilities. To verify the proposed approach, 25 cases are listed under the condition of N = 5, and 7 selected cases are compared and discussed in detail. Finally, a 75–50 Ω IT with 100% fractional bandwidth and 20 dB bandpass return loss (RL) is designed and fabricated. The measured results meet the circuit simulation and the EM simulation accurately.

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