127 research outputs found

    Design of Dual-Band Microstrip Rat Race Coupler with Circuit Miniaturization

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    Abstract- Rat race ring coupler with stepped-impedance sections is designed to have a dual-band characteristic. This is realized by attaching open stubs to both ends of each stepped-impedance section to create a phase of 900 at two designated frequencies. Transcendental equations are derived for solving impedance ratio R and lengths of the stepped-impedance sections. Circuit with miniaturized area can be obtained ifR> 1 is chosen. Such microstrip ring hybrids operating at 2.45/5.2 GHz with R = 1 and R = 4 are designed and fabricated. Experiments are performed to confirm the theory

    Microwave Slow-Wave Structure and Phase-Compensation Technique for Microwave Power Divider

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    In this paper, T-shaped electromagnetic bandgap is loaded on a coupled transmission line itself and its electric performance is studied. Results show that microwave slow-wave effect can be enhanced and therefore, size reduction of a transmission-line-based circuit is possible. However, the transmission-line-based circuits characterize varied phase responses against frequency, which becomes a disadvantage where constant phase response is required. Consequently, a phase-compensation technique is further presented and studied. For demonstration purpose, an 8-way coupled-line power divider with 22.5 degree phase shifts between adjacent output ports, based on the studied slow-wave structure and phase-compensation technique, is developed. Results show both compact circuit architecture and improved phase imbalance are realized, confirming the investigated circuit structures and analyzing methodologies

    Performance analysis of 180\ub0 HRR coupler used for direction finding with an antenna array

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    This paper presents the performance analysis of  hybrid rat race coupler, widely used in radio frequency (RF)/wireless communication systems to couple the power in the desired way. The  hybrid ring coupler consists of 4 ports, two for the input signals and two for the output signals, where sum and difference patterns of the applied two signals can be obtained at two output ports and usually called sum and difference ports. In this work, the couplers have been designed and simulated at central frequencies (fo) of 2.4 and 10 GHz using different types of substrates such as RT Duroid 5880 and FR4.  Furthermore, the coupler has been used for direction finding (angle-of-arrival estimation) application, where we combine the designed  hybrid rat race coupler with a simple two antenna elements array  (at fo=10GHz and RT Duroid =2.2) and fabricate the circuit in order to validate the performance of the coupler by measuring the direction of arrival (DoA) from  and  ports. The obtained results show that good performance can be achieved with the designs considered in this paper.

    Design and Fabrication of the Novel Miniaturized Microstrip Coupler 3dB Using Stepped Impedance Resonators for the ISM Applications

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    In this work, a novel miniaturized compact coupler using the shunt-stubs artificial transimission lines with high and low impedances is presented. Design of the proposed coupler is accomplished by modifying the length and impedance of the branch lines in the conventional structure with the planar resonators in order to achieve branch line coupler with compact size and improvement of the performances. First part of this work is focusing on the theorical study of the proposed resonators where the equations are obtained. Secondly, the proposed coupler is designed on FR4 susbtrate, and simulated by using the EM Solver (ADS from Agilent technologies and CST microwave studio) in order to operate in the ISM band. The obtained results show good agreement with the simulations and the coupler shows a good perfo6rmance in the hole bandwidth. The size of the proposed coupler is reduced around 50% compared to the conventional design. The last part conerns the fabrication and test of the proposed coupler. The measurement and simulation results are in good agreements

    Co-design of Reconfigurable and Multifunction Passive RF/Microwave Components

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    In order to meet the market demands, multi-band communication systems that are able to accommodate different wireless technologies to be compatible with different wireless standards should be investigated and realized. Multifunction and multi-band RF front-end components are promising solutions for reducing the size and enhancing the performance of multi-band communication systems. This dissertation focuses on the design and implementation of different multifunction and tunable microwave components for use in multi-standard, flexible transceiver. For frequency-domain duplexing (FDD) communication systems, in which the uplink and downlink channels are carried on different RF frequencies, a diplexer is an essential component to separate the transmitting and receiving signals from the antenna. Electrically tunable diplexers simplify the architecture of reconfigurable RF-front end. Moreover, in modern communication systems, the crowding of the spectrum and the scaling of electronics can result in higher common-mode interference and even-order non-linearity issues. In this dissertation, three tunable compact SIW-based dual-mode diplexers, with various SE (single-ended) and BAL (balanced) capabilities, are introduced for the first time. The dual-mode operation results in a dependent tuning between the two ports. The presented designs are for SE-SE, SE-BAL, and BAL-BAL. However, based on the presented design concepts, any combination of the diplexer ports can be achieved in terms of supporting the balanced and single-ended system interface. The fabricated diplexers show low insertion loss, high isolation, good tuning range and high common mode rejection. Tunable bandstop filter (BSF) is one of the essential components in the design of RF front-ends that require wide-band operations. A wide-open front-end leaves the receiver vulnerable to jamming by high-power signals. As a result, this type of front-ends requires dynamic isolation of any interfering signal. Realization of such filters in a balanced configuration, as a second function, is an important step in the realization of full-balanced RF front-ends. Balanced (differential) circuits have many important advantages over unbalanced (single-ended) circuits such as immunity to system noise, reduction of transient noise generation and inherent suppression of even-order nonlinearities. All reported balanced filters are bandpass filters that target wide pass-bands and high common-mode rejection. These filters are necessary for wide-band RF front-ends but, as mentioned above, leave the system open to interferers and jammers. In this dissertation, a new differential coupling structure for evanescent-mode cavity resonators is developed, enabling the design of fully-balanced tunable BSF. The proposed filter is tunable from 1.57-3.18 GHz with 102% tuning range. In addition, over the full range, the measured 10-dB fractional bandwidth ranges from 1-2.4%, and the attenuation level is better than 47 dB. Lastly, Substrate Integrated Waveguide (SIW) evanescent-mode cavity resonators (EVA) are employed in the design of RF couplers, quadrature hybrid and rat-race couplers. These couplers are used in the design of numerous RF front-end components such as power amplifiers, balanced mixers, and antenna array feeding networks. Utilizing such resonators (EVA) in the design allows the couplers to have wide spurious-free range, low power consumption, high power handling capability and both tunability and filtering capabilities. The proposed quadrature hybrid coupler can be tuned starting from 1.32–2.22 GHz with a measured insertion loss range from 1.29 to 0.7 dB. The measured reflection and isolation are better than 12 dB and 17 dB, respectively. Moreover, the coupler has a measured spurious free range of 5.1–3fo (lowest–highest frequency). Regarding rat-race coupler, two designs are introduced. The first design is based on a full-mode cavity while the second one is more compact and based on a half-mode cavity. Both designs show more than 70% tuning range, and the isolation is better than 30 dB

    A Novel Simple Miniaturization Technique for Microstrip Couplers

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    This paper analyzes the new compact design of couplers based on the use of microstrip lowpass filters. The proposed design achieves significant reduction in coupler size while obtaining the same characteristics as of the conventional coupler. Prototype of the coupler with the central frequency of 1 GHz was produced on the substrate with dielectric permittivity of 4.4. The experimental results showed good agreement with numerical simulations. The size of the rat-race coupler was reduced by 83.7%. © 2019 IOP Publishing Ltd.Ministry of Education and Science of the Russian Federation, Minobrnauka: № 8.2538.2017/4.6Author are grateful for the simulation software NI-AWR Design Environment provided by the National Instruments Company. The research was executed by the grant of the Ministry of education and science of the Russian Federation (project № 8.2538.2017/4.6). The research was performed on equipment of the Urals Federal University common use center

    Compact coplanar waveguide power splitter with filtering capability based on slow-wave structures

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    A compact coplanar waveguide (CPW) power splitter with filtering capability is presented in this paper. The splitter consists of a pair of 70.71 Ω impedance inverters implemented by means of inductively and capacitively loaded slow-wave structures. Such slow-wave structures efficiently shorten the length of the inverters, thereby providing substantial size reduction to the power splitter. The filtering functionality is due to the Bragg effect, related to periodicity. The proposed splitter, designed to be functional at 1 GHz, exhibits good performance at that frequency, with measured return loss of 20.6 dB and insertion loss of 3.15 dB and 3.23 dB at the output ports. Moreover, the suppression level at the first, second and third harmonic frequency is better than 12.4 dB, 34.6 dB and 24.7 dB, respectively. As compared to the length of the ordinary inverters, the length of the constitutive slow-wave impedance is reduced by a factor of tw

    Expedite Design of Variable-Topology Broadband Hybrid Couplers for Size Reduction using Surrogate-Based Optimization and Co-Simulation Coarse Models

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    In this paper, we discuss a computationally efficient approach to expedite design optimization of broadband hybrid couplers occupying a minimized substrate area. Structure size reduction is achieved here by decomposing an original coupler circuit into low- and high-impedance components and replacing them with electrically equivalent slow-wave lines with reduced physical dimensions. The main challenge is reliable design of computationally demanding low-impedance slow-wave structures that feature a quasi-periodic circuit topology for wideband operation. Our goal is to determine an adequate number of recurrent unit elements as well as to adjust their designable parameters so that the coupler footprint area is minimal. The proposed method involves using surrogate-based optimization with a reconfigurable co-simulation coarse model as the key component enabling design process acceleration. The latter model is composed in Keysight ADS circuit simulator from multiple EM-evaluated data blocks of the slow-wave unit element and theory-based feeding line models. The embedded optimization algorithm is a trust-region-based gradient search with coarse model Jacobian estimation. We exploit a penalty function approach to ensure that the electrical conditions for the slow-wave lines are accordingly satisfied, apart from explicitly minimizing the area of the coupler. The effectiveness of the proposed technique is demonstrated through a design example of two-section 3-dB branch-line coupler. For the given example, we obtain nine circuit design solutions that correspond to the compact couplers whose multi-element slow-wave lines are composed of unit cells ranging from two to ten

    Reduced Dimensions Planar Rat Race Coupler Design

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    The design of a rat race directional coupler was investigated in the Cadence AWR Design Environment program. By using low-pass filters instead of quarter-wave sections, it was possible to reduce the size of the device by 82.3%. In this case, the following deterioration of frequency characteristics occurred: narrowing of the operating frequency band by 19.3%, an increase in imbalance, and a decrease in matching. Also, the area of the compact double ring coupler was reduced by 84.5% while the bandwidth was narrowed by 29.2%

    Compact Metamaterials Induced Circuits and Functional Devices

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    In recent years, we have witnessed a rapid expansion of using metamaterials to manipulate light or electromagnetic (EM) wave in a subwavelength scale. Specially, metamaterials have a strict limitation on element dimension from effective medium theory with respect to photonic crystals and other planar structures such as frequency selective surface (FSS). In this chapter, we review our effort in exploring physics and working mechanisms for element miniaturization along with the resulting effects on element EM response. Based on these results, we afford some guidelines on how to design and employ these compact meta-atoms in engineering functional devices with high performances. We found that some specific types of planar fractal or meandered structures are particularly suitable to achieve element miniaturization. In what follows, we review our effort in Section 1 to explore novel theory and hybrid method in designing broadband and dual band planar devices. By using single or double such compact composite right-/left-handed (CRLH) atom, we show that many microwave/RF circuits, i.e., balun, rat-race coupler, power divider and diplexer, can be further reduced while without inducing much transmission loss from two perspectives of lumped and distributed CRLH TLs. In Section 2, we show that a more compact LH atom can be engineered by combining a fractal ring and a meandered thin line. Numerical and experimental results demonstrate that a subwavelength focusing is achieved in terms of smooth outgoing field and higher imaging resolution. Section 3 is devoted to a clocking device from the new concept of superscatterer illusions. To realize the required material parameters, we propose a new mechanism by combining both electric and magnetic particles in a composite meta-atom. Such deep subwavelength particles enable exact manipulation of material parameters and thus facilitate desirable illusion performances of a proof-of-concept sample constructed by 6408 gradually varying meta-atoms. Finally, we summarize our results in the last section
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