| 1. |
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| 2. |
- Deleniv, Anatoli, et al.
(author)
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Modeling gap discontinuity in coplanar waveguide using quazi-static spectral domain method
- 2000
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In: International Journal of RF and Microwave Computer-Aided Engineering. - 1096-4290 .- 1099-047X. ; 10:3, s. 150-158
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Journal article (peer-reviewed)abstract
- An efficient computer technique based on the spectral domain method is presented to solve the problem of modeling coplanar gap discontinuity. Comparison with available published data is done to confirm the accuracy of the method.
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| 3. |
- Aslam, Bilal, et al.
(author)
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A compact implantable RFID tag antenna dedicated to wireless health care
- 2017
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : John Wiley & Sons. - 1096-4290 .- 1099-047X. ; 27:5
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Journal article (peer-reviewed)abstract
- Implantable tag antennas are an integral component of contemporary pervasive patient monitoring setups envisioned to reduce the medical errors and improve the quality of health care facilities. These tags, embedded into the human body, transmit critical patient information to the external equipment via a wireless communication link. This research article presents an implantable compact folded dipole antenna of size 10 mm 3 15 mm 3 2 mm, designed to operate in the industrial-scientificmedical band (2.4-2.48GHz). A three-layered phantom representing the human arm is used to evaluate the subcutaneous antenna performance. The tag antenna embedded in the middle of the fat layer offers a maximum gain of 216.3 dBi. The tag antenna performance as a function of implant position and phantom dimensions is analyzed. Link budget calculations show that with the achieved antenna gain the link power exceeds the required power by 38.37 dBm, and hence wireless communication is viable.
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| 4. |
- Aslam, Bilal, et al.
(author)
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A high capacity tunable retransmission type frequency coded chipless radio frequency identification system
- 2019
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : WILEY. - 1096-4290 .- 1099-047X. ; 29:9
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Journal article (peer-reviewed)abstract
- This article presents a 12-bit frequency coded chipless RFID system in the frequency range of 3 to 6 GHz. The system consists of a fully printable chipless tag and a pair of high-gain reader antennas. The tag also incorporates its own antennas to improve the read range. Information is encoded into frequency spectrum using a multi-resonant circuit. The circuit consists of multiple microstrip U and L-shaped open stub resonators patterned in a unique configuration. The proposed configuration aids in capturing more data in a reduced space as well as tunable frequency operation. Tag and reader antennas utilize techniques such as stepped impedance feeding line, defective partial ground plane, and stair-step patch structure to achieve wide-band impedance bandwidth in miniature size. The results of the wireless measurements in the non-anechoic environment show that the proposed system has a reading range of more than 20 cm. The presented system possesses great potential for low-cost short-range inventory tracking.
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| 5. |
- Aslam, B., et al.
(author)
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Miniaturized decoupled slotted patch RFID tag antennas for wearable health care
- 2017
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : John Wiley & Sons. - 1096-4290 .- 1099-047X. ; 27:1
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Journal article (peer-reviewed)abstract
- In this article, a couple of two-layered RFID tag antenna designs exhibiting improved performance descriptors for on-body applications are presented. The antennas are designed to operate in the microwave band (2.4–2.48 GHz) ensuring high data transmission rates ideal for real-time subject monitoring applications. The radiating element of both the antennas is a slotted patch structure provisioned with a pair of T-shaped slots realized on a commercial FR4 substrate. The augmentation of a systematic sequence of narrow comb-like etchings into the design enhances the impedance bandwidth considerably. A high permittivity silicon layer embedded with the radiating patch provides resilience from the human body dielectric losses. A modified antenna design utilizing patch miniaturization technique, resulting in an overall footprint reduction by 32%, is also proposed. The designed tag antennas offer a gain of more than 1.8 dBi and an attractive read range greater than 6.8 m in the operating band.
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| 6. |
- Aziz, Imran, et al.
(author)
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28 GHz Circular Polarized Fan-out Antenna Array with Wide-angle Beam-steering
- 2022
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Publishing Corporation. - 1096-4290 .- 1099-047X. ; 32:3
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Journal article (peer-reviewed)abstract
- The article presents 28 GHz circular polarized antenna arrays designed in an embedded wafer level ball grid array (eWLB) package for 5G applications. The antenna arrays are realized on a re-distribution layer (RDL) in the fan-out region of the chip package. Two separate but identical arrays perform RX and TX operations where a crossed dipole is used as a building block of the array. These 4-element arrays have <−10 dB impedance bandwidth covering 25.3–29.8 GHz (4.5 GHz bandwidth) while presenting 10 dBi maximum realized gain. The measurement results show <3 dB axial ratio in the band 26–29.5 GHz, and the main beam can be steered in ±50° in the azimuth plane when array elements are fed by appropriate phases from the chip. The radio frequency module provides 31 dBm maximum equivalent isotropic radiated power (EIRP).
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| 7. |
- Chagtmi, Nadia, et al.
(author)
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Augmented Hammerstein model for the calibration of six-port based dual band wireless receivers
- 2019
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 29:2
-
Journal article (peer-reviewed)abstract
- Two architectures of concurrent dual-band six-port-based receiver (SPR), which are modeled and calibrated using the augmented Hammerstein model (AHM) are proposed for the first time in this article. The receivers are based on six-port junctions with one or two local oscillators (LO). The proposed single step calibration algorithms achieve the recovery of the two in-phase (I1 and I2) and quadrature (Q1 and Q2) components of an RF signal with two frequency components (RF1 and RF2). Experimental validations have been performed to verify the performance of the proposed concurrent dual-band receivers and to test the efficiency of the AHM based calibration algorithms. As a performance metric, the Error Vector Magnitude (EVM) has been measured to compare the transmitted and recovered baseband signals and to evaluate the performance and efficiency of the proposed calibration algorithms for the two receiver topologies. The IQ data has been recovered with EVMs no higher than 2% for the two LOs based receiver excited with a QAM modulated dual-band RF signal. The single LO based receiver has been tested with a dual-band LTE signal and the recovered IQ data exhibited EVMs no higher than 4%.
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| 8. |
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| 9. |
- Fan, Jin, et al.
(author)
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Investigation of ultra-wideband Bowtie antennas for phased array feed application
- 2020
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 30:11
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Journal article (peer-reviewed)abstract
- In this article, two new ultra-wideband (UWB) dual-polarized Bowtie antennas are investigated as the elements for a phased array feed for reflectors. In addition to its UWB impedance matching characteristic, the Bowtie antennas have stable large beam-width and a low cross-polar level over a wide frequency band with a compact size, which is an essence for phased array applications. The simulated and measured results state a low ohmic loss, good impedance matching (S11 below −15 dB) and good radiation performance, with a simple structure for easy manufacturing. The proposed antennas can be good candidates for phased array feed (PAF) in FAST and the SKA (square kilometer array) pathfinder PHAROS2 projects, and massive MIMO antennas in wireless communication systems.
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| 10. |
- Fanyaev, I., et al.
(author)
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Synthesis of novel 8 x 8 beam-forming network for broadband multibeam antenna array
- 2022
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In: International Journal of Rf and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 32:2
-
Journal article (peer-reviewed)abstract
- Synthesis of a novel 8 x 8 beam-forming network (BFN) for broadband multi-beam antenna arrays in the X-band has been proposed. The synthesized BFN has 6 less path crossings than a classic Butler matrix. The BFN design is realized using basic elements such as slot-line transition and magic-Ts. A numerical simulation for the analysis of the frequency characteristics of the proposed BFN is carried out. In addition, we offer a design of an eight-channel multibeam antenna array consisting of the synthesized BFN and Vivaldi antennas. Eight spatial beams cover approximately 120 degrees in the azimuth plane with a peak gain of 12 dB in the range of 8.3-11.7 GHz. The proposed broadband multibeam antenna array has good performance, compactness, and ease of fabrication that would be an attractive candidate for radar, satellite communication, and wireless computer networks.
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| 11. |
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| 12. |
- Isaksson, Magnus, et al.
(author)
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A Parameter-Reduced Volterra Model for Dynamic RF Power Amplifier Modeling based on Orthonormal Basis Functions
- 2007
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 17:6, s. 542-551
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Journal article (peer-reviewed)abstract
- A nonlinear dynamic behavioral model for radio frequency power amplifiers is presented. It uses orthonormal basis functions, Kautz functions, with complex poles that are different for each nonlinear order. It has the same general properties as Volterra models, but the number of parameters is significantly smaller. Using frequency weighting the out-of-band model error can be reduced. Using experimental data it was found that the optimal poles were the same for different input powers and for the different nonlinear orders. The optimal poles were also the same for direct and inverse models, which could be explained theoretically to be a general property of nonlinear systems with negligible linear memory effects. The model can be used as either a direct or inverse model with the same model error for power amplifiers with negligible linear memory effects.
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| 13. |
- Jabeen, Iqra, et al.
(author)
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Elliptical slot based polarization insensitive compact and flexible chipless RFID tag
- 2019
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : WILEY. - 1096-4290 .- 1099-047X. ; 29:11
-
Journal article (peer-reviewed)abstract
- A miniaturized, polarization insensitive, and fully passive chipless radio frequency identification tag is proposed in this research article. The realized tag is based on slotted elliptical structures in a nested loop fashion with identical lengths and widths of slot resonators. Alteration of data sequence is accomplished by addition and elimination of nested resonators in the geometric structure. The tag is capable to encode 10 bits of data and covers spectral range from 3.6 to 15.6 GHz. The formulated structure demonstrates polarization insensitive characteristic. The data encoding structure is analyzed and optimized for different substrates that are, Rogers RT/duroid/5880, Rogers RT/duroid/5870, and Taconic TLX-0 over the miniaturized footprint of 22.8 x 16 mm(2). The presented tag is robust, novel, compact, and flexible exhibiting a stable response to impinging electromagnetic waves at various angles of incidence.
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| 14. |
- Khan, T. A., et al.
(author)
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Radiation pattern synthesis in conformal antenna arrays using modified convex optimization technique
- 2022
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 32:11
-
Journal article (peer-reviewed)abstract
- In this paper, a modified convex optimization technique is used for radiation pattern correction in a cylindrical-shaped conformal microstrip array antenna. The technique uses numerical simulations to optimize the amplitude and phase excitations, with the goal to decrease the Euclidean distance between the desired field pattern and the obtained (simulated/measured) field pattern while maintaining the main beam direction, null's location, and side lobe levels under control. Two prototypes of (Formula presented.) and (Formula presented.) conformal microstrip antenna array deformed from linear/planar structure to the prescribed cylindrical shape, with different radii of curvature, are studied to demonstrate the performance of the proposed technique. The proposed convex optimization model when applied to conformal antenna array possesses fast computing speed and high convergence accuracy for radiation pattern synthesis, which can be a valuable tool for engineering applications.
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| 15. |
- Landin, Per N., 1983-, et al.
(author)
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Parameter Extraction and Performance Evaluation Method for Increased Performance in RF Power Amplifier Behavioral Modeling
- 2010
-
In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 20:2, s. 200-208
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Journal article (peer-reviewed)abstract
- A frequency-weighted parameter extraction method based on the performance evaluation criterion weighted error spectral power ratio (WESPR) is proposed. Performance of models extracted using the normalized mean square error (NMSE) are compared to the performances of models extracted using the WESPR. The results show an increase in performance with a decrease in model complexity.
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| 16. |
- Liu, Hui, et al.
(author)
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Design of novel compact dual-band filtering power divider using stepped-impedance resonators with high selectivity
- 2016
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : John Wiley & Sons. - 1096-4290 .- 1099-047X. ; 29:3, s. 262-267
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Journal article (peer-reviewed)abstract
- A novel compact dual-band power divider with filtering responses is presented in this article. The proposed circuit utilizes coupled quarter-wavelength stepped-impedance resonators. By controlling these resonators, dual-band operation can be realized. Furthermore, a resistor is connected between the two open ends of the input feed line to obtain good isolation at two bands. Source load coupling is utilized to enhance the selectivity. To verify the proposed idea, a filtering power divider with the operating frequencies of 2.4 and 5.8 GHz is implemented. Good agreement between the simulated and measured results validates the proposed idea. The total size of the circuit is 0.23(g) x 0.28(g), where (g) is the guide wavelength of 2.4 GHz.
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| 17. |
- Piazzon, L., et al.
(author)
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Design Method for Quasi-Optimal Multiband Branch-Line Couplers
- 2014
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 24:1, s. 117-129
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Journal article (peer-reviewed)abstract
- In this article, the design approach, the implementation, and experimental results of multiband branch-line couplers operating at arbitrary frequencies are presented. The conventional branch-line coupler structure is adapted to multiband operation by shunting its four ports with multiband reactive networks. The performance of the proposed multiband couplers is theoretically analyzed and optimized through the even-odd mode circuit analysis. Dual-band (2.4-3.5 GHz), triple-band (1.5-2.4-4.2 GHz), and quad-band (1.5-2.4-3.5 GHz) microstrip branch-line couplers have been realized and tested to verify the design method. The good experimental results (input return loss greater than 15 dB and amplitude imbalance lower than 0.7 dB) show excellent agreement with theoretical and simulated ones, thus validating the proposed approach.
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| 18. |
- Reyaz, Shakila, et al.
(author)
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A W-band RF-MEMS switched LNA in a 70 nm mHEMT process
- 2015
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 25:7, s. 639-646
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Journal article (peer-reviewed)abstract
- This work presents a monolithic integrated reconfigurable active circuit consisting of a W-band RF micro-electro-mechanical-systems (MEMS) Dicke switch network and a wideband low-noise amplifier (LNA) realized in a 70 nm gallium arsenide (GaAs) metamorphic high electron mobility transistor process technology. The RF-MEMS LNA has a measured gain of 10.2-15.6 dB and 1.3-8.2 dB at 79-96 GHz when the Dicke switch is switched ON and OFF, respectively. Compared with the three-stage LNA used in this design the measured in-band noise figure (NF) of MEMS switched LNA is minimum 1.6 dB higher. To the authors' knowledge, the experimental results represent a first time demonstration of a W-band MEMS switched LNA monolithic microwave integrated circuit (MMIC) in a GaAs foundry process with a minimum NF of 5 dB. The proposed novel integration of such MEMS switched MMICs can enable more cost-effective ways to realize high-performance single-chip mm-wave reconfigurable radiometer front-ends for space and security applications, for example. (c) 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:639-646, 2015.
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| 19. |
- Satti, Javeria Anum, et al.
(author)
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Miniaturized humidity and temperature sensing RFID enabled tags
- 2018
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 28:1
-
Journal article (peer-reviewed)abstract
- A compact 27-bit linearly polarized chipless radio frequency identification tag is presented in this research. The proposed tag is designed with an overall tag dimension of 23 x 23 mm(2). The tag comprises of metallic (copper) rings-based structure loaded with slots. These slots correspond to a particular sequence of bits. The circular tag is analysed using 2 different substrates, that is, Rogers RT/duroid/5870 and flexible Rogers RT/duroid/5880. The radar cross-section response of frequency signatured tag is analysed for humidity and temperature sensor designs. Humidity sensing is achieved by deploying a DuPont Kapton HN heat resistant sheet on the shortest slot of the tag, that is, the sensing slot. Temperature sensing is attained using Rogers RT/duroid/5870 and Stanyl polyamide as a combined substrate. Hence, the miniaturized, robust, and flexible tag can be deployed over irregular surfaces for sensing purposes.
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| 20. |
- Wu, Zhe, et al.
(author)
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A wide-band all-metal and high-gain omnidirectional antenna with simple prototype
- 2022
-
In: International Journal of RF and Microwave Computer-Aided Engineering. - : WILEY. - 1096-4290 .- 1099-047X. ; 32:1
-
Journal article (peer-reviewed)abstract
- An all-metal dipole two-element array antenna is proposed to achieve a wide-band impedance bandwidth and an omnidirectional radiation pattern. The concept of this antenna derives from a quarter-shorted magnetic dipole structure. The proposed antenna consists of an air-filled metallic parallel bi-plate and two dipole elements. The dipole elements are perpendicularly fabricated at the open end of the bi-plate. Fed by a single coaxial SMA connector in the center of this structure, a quasi-TEM mode in the bi-plate can be excited similar to the parallel waveguide. Based on the multiple resonances and line-array effect, the proposed antenna can achieve a wide-band working bandwidth and a stable omnidirectional pattern. Simulated and experimental results confirm that this antenna has a peak gain of 4.16 dBi and a relative impedance bandwidth of 72% (0.8-1.7 GHz). The proposed antenna can be used in UAV (unmanned aerial vehicle) application.
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| 21. |
- Xiao, Fei, et al.
(author)
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Quasi-TEM approach of coupled-microstrip lines and its application to the analysis of microstrip filters
- 2012
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In: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 22:1, s. 131-139
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Journal article (peer-reviewed)abstract
- In this article, the quasi-TEM approach is successfully used to analyze coupled-microstrip lines of finite length, which are usually used for the coupling between the source/load and resonators in microstrip filters. First, an orthogonal expansion method is used to extract the per-length inductance and capacitance matrices. The authors then obtain the impedance matrix or admittance matrix, which relates the voltages and currents at both ends of coupled-microstrip lines. To verify our theory, an example is presented, i.e., a Y-shaped dual-mode bandpass microstrip filter, for which, the equivalent circuit model based on the quasi-TEM analysis of coupled-microstrip lines is accurately set up. The approach in this article is applicable to planar microstrip lines with arbitrary number of conductors, under the quasi-TEM assumption.
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| 22. |
- Xu, Xin, et al.
(author)
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Broadband and low-loss composite right/left-handed transmission line based on broadside-coupled lines
- 2019
-
In: International Journal of RF and Microwave Computer-Aided Engineering. - : WILEY. - 1096-4290 .- 1099-047X. ; 29:8
-
Journal article (peer-reviewed)abstract
- A novel composite right/left-handed (CRLH) transmission line (TL) structure is proposed and investigated. This structure consists of a pair of broadside-coupled lines and a shorted stub. First, its fundamental characteristics and the relation between its electrical parameters and bandwidth are studied utilizing the TL theory. Then, closed-form design equations with flexible parameter selection are given. Finally, several microstrip implementations of the proposed structure are developed to verify our theoretical results. It is shown that the proposed structure can achieve a very wide left-handed (LH) and right-handed (RH) bandwidth with low insertion loss and low return loss.
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| 23. |
- Zahra, Anum, et al.
(author)
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A chipless RFID tag for smart temporal applications
- 2018
-
In: International Journal of RF and Microwave Computer-Aided Engineering. - : WILEY. - 1096-4290 .- 1099-047X. ; 28:8
-
Journal article (peer-reviewed)abstract
- A compact, robust, chipless radio frequency identification (RFID) tag is proposed. Resonant elements patterned in a concentric fashion encode data in the spectral domain employing frequency shift encoding. The proposed tag encodes 28.25 data bits over a miniscule physical footprint of 25 x 25 mm(2). The formulated scheme is demonstrated to be viable for encoding of temporal variables. The electromagnetic performance of the presented design is investigated for different laminates: Rogers RT/duroid (R) 5880 and Taconic TLX-0. Multiple tag prototypes employing a variety of substrates are realized and evaluated for in-laboratory performance. The proposed design is compared with existing work reported in literature. Code density of 4.52 bits/cm(2) has been successfully achieved. The tag design operates from 3.07 to 10.6 GHz and is readily realizable on flexible laminates. Smart retail, intelligent packaging, adaptive ticketing, and similar time-related applications can be materialized using the proposed tag.
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