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Sarika, n., Kumar, R., Tripathy, M. T. & Rönnow, D. (2019). An approach to improve gain and bandwidth in bowtie antenna using frequency selective surface. In: Bijaya Ketan Panigrahi, Munesh C. Trivedi, Krishn K. Mishra, Shailesh Tiwari, Pradeep Kumar Singh (Ed.), Smart Innovations in Communication and Computational Sciences: Proceedings of ICSICCS 2017, Volume 1. Paper presented at International Conference on Smart Innovations in Communications and Computational Sciences (ICSICCS 2017), Punjab, India, 23-24 June 2017 (pp. 219-227). Springer
Open this publication in new window or tab >>An approach to improve gain and bandwidth in bowtie antenna using frequency selective surface
2019 (English)In: Smart Innovations in Communication and Computational Sciences: Proceedings of ICSICCS 2017, Volume 1 / [ed] Bijaya Ketan Panigrahi, Munesh C. Trivedi, Krishn K. Mishra, Shailesh Tiwari, Pradeep Kumar Singh, Springer, 2019, p. 219-227Conference paper, Published paper (Refereed)
Abstract [en]

A novel approach of improving gain and bandwidth of bowtie antenna using Frequency Selective Surface (FSS) is presented. A 42 × 66 mm2 bowtie antenna is used. The 5 mm × 5 mm FSS unit cell consists of metallic square loop and grid wires on FR4 substrate with permittivity of 4.4 and loss tangent = 0.02. The effect of FSS layer on bowtie antenna is investigated in terms of parameters like gain and bandwidth. Simulation results show that gain and bandwidth of the bowtie antenna gets increased by a factor of two when the FSS layer is kept on it. Further, the effect of change of height of the substrate on gain and bandwidth is also studied. The proposed structure shows applications in X-band and Ku-band range. High-Frequency Structural Simulator (HFSS) software is used for the simulation. © Springer Nature Singapore Pte Ltd. 2019.

Place, publisher, year, edition, pages
Springer, 2019
Series
Advances in Intelligent Systems and Computing, ISSN 2194-5357, E-ISSN 2194-5365 ; 669
Keywords
Bandwidth enhancement, Bowtie, Frequency selective surface, HFSS, Bandwidth, Computer software, Microwave antennas, Bow tie, Bow-tie antennas, Change of heights, Frequency selective surface (FSS), Gain and bandwidths, High frequency HF, Frequency selective surfaces
National Category
Signal Processing
Identifiers
urn:nbn:se:hig:diva-27652 (URN)10.1007/978-981-10-8968-8_19 (DOI)2-s2.0-85049349640 (Scopus ID)978-981-10-8967-1 (ISBN)978-981-10-8968-8 (ISBN)
Conference
International Conference on Smart Innovations in Communications and Computational Sciences (ICSICCS 2017), Punjab, India, 23-24 June 2017
Available from: 2018-08-15 Created: 2018-08-15 Last updated: 2018-09-03Bibliographically approved
Sarika, ., Tripathy, M. R. & Rönnow, D. (2018). A wideband frequency selective surface reflector for 4G/X-Band/Ku-Band. Progress In Electromagnetics Research C, 81, 151-159
Open this publication in new window or tab >>A wideband frequency selective surface reflector for 4G/X-Band/Ku-Band
2018 (English)In: Progress In Electromagnetics Research C, ISSN 1937-8718, E-ISSN 1937-8718, Vol. 81, p. 151-159Article in journal (Refereed) Published
Abstract [en]

A Frequency Selective Surface (FSS) reflector with wideband response for 4G/X-band/Ku-band is proposed. The wideband FSS reflector consists of cascaded dual-layer patch FSS which is etched on separate layers of FR4 substrate. The targeted frequency range is 5–16 GHz. A wide stopband of 10.4 GHz (100% percent bandwidth) is obtained with two layers in cascade. The Equivalent Circuit (EC) method is used to approximate the simulated results. An extensive parametric study is also carried out to understand the effect of various combinations of FSS layers and their disposition. A panel of final FSS is fabricated where measured and simulated results agree well.

Place, publisher, year, edition, pages
Electromagnetics Academy, 2018
Keywords
Equivalent circuits, Reflection, Dual layer, FR4 substrates, Frequency ranges, Frequency selective surface (FSS), Parametric study, Simulated results, Wide band frequencies, Wide stopband, Frequency selective surfaces
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-26241 (URN)2-s2.0-85042380788 (Scopus ID)
Available from: 2018-03-15 Created: 2018-03-15 Last updated: 2018-04-25Bibliographically approved
Alizadeh, M., Händel, P. & Rönnow, D. (2018). Basis Function Decomposition Approach in Piece-Wise Modeling for RF Power Amplifiers. In: 6th Telecommunications forum TELFOR 2018: . Paper presented at 26th Telecommunications Forum TELFOR 2018, Belgrade, Serbia, 20-21 November 2018. Belgrade: Telecommunications society
Open this publication in new window or tab >>Basis Function Decomposition Approach in Piece-Wise Modeling for RF Power Amplifiers
2018 (English)In: 6th Telecommunications forum TELFOR 2018, Belgrade: Telecommunications society , 2018Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, a new approach is proposed to decompose the basis functions in a piece-wise modeling technique for nonlinear radio frequency (RF) power amplifiers. The proposed technique treats the discontinuity problem of the model output at the joint points between different operating points, whereas preserves the linear and nonlinear properties of the original model within each region. Experimental results show that the proposed technique outperforms the conventional piece-wise model in terms of model errors.

Place, publisher, year, edition, pages
Belgrade: Telecommunications society, 2018
Keywords
Nonlinear dynamic RF power amplifier, behavioral modeling, piece-wise models, digital predistortion.
National Category
Signal Processing
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:hig:diva-29303 (URN)10.1109/TELFOR.2018.8611865 (DOI)978-1-5386-7171-9 (ISBN)978-1-5386-7172-6 (ISBN)978-1-5386-7170-2 (ISBN)
Conference
26th Telecommunications Forum TELFOR 2018, Belgrade, Serbia, 20-21 November 2018
Note

Proceedings distributed on CD.

Available from: 2019-01-11 Created: 2019-02-18 Last updated: 2019-03-01Bibliographically approved
Alizadeh, M., Händel, P. & Rönnow, D. (2018). Behavioural modelling and digital pre-distortion techniques for RF PAs in a 3x3 MIMO system. International journal of microwave and wireless technologies
Open this publication in new window or tab >>Behavioural modelling and digital pre-distortion techniques for RF PAs in a 3x3 MIMO system
2018 (English)In: International journal of microwave and wireless technologies, ISSN 1759-0795, E-ISSN 1759-0787Article in journal (Refereed) Submitted
Abstract [en]

Modern telecommunications are moving towards (massive) multi-input multi-output systems in 5th generation (5G) technology, increasing the dimensionality of the system dramatically. In this paper, the impairments of radio frequency (RF)power amplifiers (PAs) in a 3x3 MIMO system are compensated in both time and frequency domains. A three-dimensional(3D) time-domain memory polynomial-type model is proposed as an extension of conventional 2D models. Furthermore, a 3D frequency-domain technique is formulated based on the proposed time-domain model to reduce the dimensionality of the model, while preserving the performance in terms of model errors. In the 3D frequency-domain technique, the bandwidth of a system is split into several narrow sub-bands, and the parameters of the system are estimated for each subband. This approach requires less computational complexity, and also the procedure of the parameters estimation for each sub-band can be implemented independently. The device-under-test (DUT) consists of three RF PAs including input and output cross-talk channels. The proposed techniques are evaluated in both behavioural modelling and digital pre-distortion(DPD) perspectives. The results show that the proposed DPD technique can compensate the errors of non-linearity and memory effects by about 23.5 dB and 7 dB in terms of the normalized mean square error and adjacent channel leakage ratio, respectively.

Keywords
Radio frequency power amplifier, non-linearity, memory effects, multiple-input multiple-output (MIMO), digital pre-distortion.
National Category
Signal Processing
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:hig:diva-29304 (URN)
Available from: 2019-01-11 Created: 2019-02-18 Last updated: 2019-02-18Bibliographically approved
Alizadeh, M., Rönnow, D. & Händel, P. (2018). Characterization of Volterra Kernels for RF Power Amplifiers Using a Two-Tone Signal and a Large-Signal. In: 2018 International Conference on Communications, COMM 2018 - Proceedings: . Paper presented at 2018 International Conference on Communications (COMM), 14-16 June 2018, Bucharest, Romania (pp. 351-356). Institute of Electrical and Electronics Engineers (IEEE), 1
Open this publication in new window or tab >>Characterization of Volterra Kernels for RF Power Amplifiers Using a Two-Tone Signal and a Large-Signal
2018 (English)In: 2018 International Conference on Communications, COMM 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, Vol. 1, p. 351-356Conference paper, Published paper (Refereed)
Abstract [en]

The 3rd-order Volterra kernels of a radio frequency (RF) power amplifier (PA) are characterized using a large-signal and a two-tone probing-signal. In this technique, the magnitude and phase asymmetries of the kernels of the PA excited by the probing-signal are analyzed in different amplitude regions of the large-signal. The device under test is a class-AB PA operating at 2.14 GHz. The maximum sweeping frequency space of the probing-signal is 20 MHz. The results indicate that the Volterra kernels of the PA show different behaviors (frequency dependency and asymmetry) in different regions.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
Keywords
Kernel, Radio frequency, Baseband, Nonlinear systems, Frequency dependence, Frequency-domain analysis, Discrete Fourier transforms, nonlinear dynamic RF power amplifier, volterra kernels, asymmetry, two-tone test
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-27867 (URN)10.1109/ICComm.2018.8430119 (DOI)000449526000066 ()2-s2.0-85052507435 (Scopus ID)978-1-5386-2351-0 (ISBN)978-1-5386-2350-3 (ISBN)978-1-5386-2349-7 (ISBN)
Conference
2018 International Conference on Communications (COMM), 14-16 June 2018, Bucharest, Romania
Available from: 2018-09-06 Created: 2018-09-06 Last updated: 2019-02-18Bibliographically approved
Eroglu, A. & Rönnow, D. (2018). Design of multilayer and multiline microstrip directional coupler with closed form relations. Progress In Electromagnetics Research C, 83, 1-14
Open this publication in new window or tab >>Design of multilayer and multiline microstrip directional coupler with closed form relations
2018 (English)In: Progress In Electromagnetics Research C, ISSN 1937-8718, E-ISSN 1937-8718, Vol. 83, p. 1-14Article in journal (Refereed) Published
Abstract [en]

Design, simulation, implementation and measurement results of multiline and multilayer microstrip directional couplers are given with closed form relations. Step-by-step design procedure reflecting the design practice of directional couplers, which requires only information on coupling level, port impedances and operational frequency, is presented. The method based on the synthesis technique applied in the design of conventional two-line microstrip symmetrical directional couplers is adapted to design multilayer directional couplers with the aid of electromagnetic simulators using parametric analysis with curve fitting method. The proposed design method is compared with the measurement results and accuracy is verified. It has been also shown that the directivity of the couplers designed using the multilayer structure is improved significantly. A method such as the one presented in this paper can be used to design multilayer two-line and three-line directional couplers which can be integrated to the front end of an RFID systems to provide the required isolation between transmitter and receiver and prevent signal leakage due to use of conventional circulators.

Place, publisher, year, edition, pages
Electromagnetics Academy, 2018
Keywords
Curve fitting, Directional couplers, Elastic moduli, Electromagnetic simulation, Multilayers, Optical waveguides, Signal receivers, Closed-form relations, Curve fitting methods, Electromagnetic simulators, Multilayer microstrip, Multilayer structures, Operational frequency, Parametric -analysis, Transmitter and receiver, Design
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-26736 (URN)2-s2.0-85045089592 (Scopus ID)
Available from: 2018-06-04 Created: 2018-06-04 Last updated: 2018-06-04Bibliographically approved
Händel, P. & Rönnow, D. (2018). Dirty MIMO Transmitters: Does It Matter?. IEEE Transactions on Wireless Communications, 17(8), 5425-5436
Open this publication in new window or tab >>Dirty MIMO Transmitters: Does It Matter?
2018 (English)In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 8, p. 5425-5436Article in journal (Refereed) Published
Abstract [en]

The radio frequency transmitter is a key component in contemporary MIMO OFDM systems. A detailed study of a 2×2 MIMO transmitter subjected to correlated input data streams, nonlinear distortion, thermal noise, and crosstalk is provided by stochastic modeling. The effects of correlated input streams, crosstalk and nonlinearities are studied in detail, and exemplified both by approximate expressions and numerical simulations. Key results include exact and approximate expressions for the normalized mean-squared error (NMSE) for systems with or without digital predistortion, the relationship between NMSE and the signal-to-noise-and-distortion ratio, the properties of the distortion noise, and a novel design for power amplifier back-off for MIMO-transmitters subject to crosstalk. The theoretical derivations are illustrated by numerical examples and simulation results, and their relationship to state-of-the-art research are discussed. OAPA

Place, publisher, year, edition, pages
IEEE, 2018
Keywords
Bussgang theory, Crosstalk, input back-off, MIMO communication, Nonlinear distortion, OFDM, optimization, Orthogonal frequency division multiplexing (OFDM), power amplifier, Radio transmitters, Mean square error, Nonlinear optics, Orthogonal frequency division multiplexing, Power amplifiers, Radio frequency amplifiers, Radio transmission, Signal to noise ratio, Stochastic systems, Thermal noise, Transmitters, Approximate expressions, Input-back offs, Normalized mean squared errors, Radio frequency transmitters, Signal to noise and distortion ratio, Theoretical derivations, MIMO systems
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-27518 (URN)10.1109/TWC.2018.2843764 (DOI)000441933900034 ()2-s2.0-85048562714 (Scopus ID)
Available from: 2018-07-04 Created: 2018-07-04 Last updated: 2018-11-26Bibliographically approved
Sarika, n., Kumar, R., Tripathy, M. R. & Rönnow, D. (2018). Fractal frequency selective surface based band stop filters for X-band and Ku-band applications. In: Proceedings - 2017 3rd International Conference on Advances in Computing, Communication and Automation (Fall), ICACCA 2017: . Paper presented at 3rd International Conference on Advances in Computing, Communication and Automation (Fall), ICACCA 2017, 15-16 Spetember 2017; Dehradun, India.
Open this publication in new window or tab >>Fractal frequency selective surface based band stop filters for X-band and Ku-band applications
2018 (English)In: Proceedings - 2017 3rd International Conference on Advances in Computing, Communication and Automation (Fall), ICACCA 2017, 2018Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, band stop filters using Fractal Frequency Selective Surface (FSS) approach for X-band and Ku-band applications are presented. A 10 mm χ 10 mm FSS unit cell is used and is evolved into four stages to get the fractal approach. Numerical results are calculated using Finite element method solver for electromagnetic structures from Ansys ie. HFSS. The transmission coefficients for each stage confirm the band stop filter property of FSS for X-band and Ku-band. Variation in arm length 'd' is studied both in horizontal and vertical direction respectively to calculate the change in narrow bands and bandwidth.

Keywords
Band stop, filters, Fractal, Frequency Selective Surface, Filters (for fluids), Fractals, Frequency selective surfaces, Magnetic filters, Numerical methods, Band-stop, Band-stop filters, Electromagnetic structure, Fractal approach, Frequency selective surface (FSS), Numerical results, Transmission coefficients, Vertical direction, Notch filters
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-27651 (URN)10.1109/ICACCAF.2017.8344692 (DOI)2-s2.0-85049749215 (Scopus ID)9781509064038 (ISBN)
Conference
3rd International Conference on Advances in Computing, Communication and Automation (Fall), ICACCA 2017, 15-16 Spetember 2017; Dehradun, India
Available from: 2018-08-15 Created: 2018-08-15 Last updated: 2018-12-06Bibliographically approved
Kumar, R., Tripathy, M. R. & Rönnow, D. (2018). Multi-resonant Bowtie Antenna with Modified Symmetric SRR for Wireless Applications. IETE Journal of Research
Open this publication in new window or tab >>Multi-resonant Bowtie Antenna with Modified Symmetric SRR for Wireless Applications
2018 (English)In: IETE Journal of Research , E-ISSN 0974-780XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

A modified symmetric split ring resonator (MSSRR) loaded bowtie antenna with multi-band features over a range of 1.6–7.1 GHz is proposed in this paper. The antenna is designed on FR4 substrate with relative permittivity εr = 4.1 and thickness 1.5 mm. The fabricated antenna size is 40 mm × 58 mm. The Modified Symmetric SRR used beneath the substrate is novel and consists of two circles that are broken into four quarter circles by four rods. The effect of MSSRR location and its geometry is investigated and analysed thoroughly. The measurement results of the fabricated antenna are in good agreement with the simulation results, which confirms the proposed antenna design’s properties. ANSYS High Frequency Structural Simulator (HFSS) software is used for simulating the antenna.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2018
Keywords
Antenna, Bowtie, HFSS, Meta-material, Radiation pattern, SRR, Antennas, Computer software, Geometry, Microwave antennas, Ring gages, Wireless telecommunication systems, Bow tie, Bow-tie antennas, High frequency HF, Quarter circles, Relative permittivity, Split ring resonator, Wireless application, Directional patterns (antenna)
National Category
Signal Processing
Identifiers
urn:nbn:se:hig:diva-27359 (URN)10.1080/03772063.2018.1479663 (DOI)2-s2.0-85048508061 (Scopus ID)
Available from: 2018-06-25 Created: 2018-06-25 Last updated: 2019-01-08Bibliographically approved
Rönnow, D. (2018). pth-order inverse of the Volterra series for multiple-input multiple-output non-linear dynamic systems. IET Circuits, Devices & Systems, 12(4), 403-412
Open this publication in new window or tab >>pth-order inverse of the Volterra series for multiple-input multiple-output non-linear dynamic systems
2018 (English)In: IET Circuits, Devices & Systems, ISSN 1751-858X, E-ISSN 1751-8598, Vol. 12, no 4, p. 403-412Article in journal (Refereed) Published
Abstract [en]

A method to determine the pth-order inverse of the Volterra series of multiple-input multiple-output non-linear dynamic systems is presented; it combines time- and frequency-domain techniques to determine the Volterra series of the inverse as a function of the forward system's Volterra series. The method can be used for continuous and discrete time systems. Each operator of non-linear order n of the inverse is a function of the forward system's operators of non-linear order n and lower. It is shown that the pth-order post-inverse is equal to the pth-order preinverse. For the special case that there are no linear cross terms and that the linear memory effects are negligible the kernels of the forward and inverse models are approximately the same. In an example, an approximate inverse model of a model of a concurrent dual band radio frequency amplifier is derived. © The Institution of Engineering and Technology 2018.

Place, publisher, year, edition, pages
Institution of Engineering and Technology, 2018
Keywords
Codes (symbols), Continuous time systems, Digital control systems, Discrete time control systems, Feedback control, Frequency domain analysis, Inverse problems, Linear control systems, Radio frequency amplifiers, Telecommunication repeaters, Approximate inverse, Discrete - time systems, Dual band radios, Inverse models, Memory effects, Non-linear dynamic systems, Time and frequency domains, Volterra Series, MIMO systems
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-27865 (URN)10.1049/iet-cds.2017.0447 (DOI)000440944500013 ()2-s2.0-85051249953 (Scopus ID)
Available from: 2018-09-06 Created: 2018-09-06 Last updated: 2018-09-06Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2887-049x

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