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  • 1.
    Andersson, Daniel
    et al.
    Radarbolaget, Gävle.
    Wallin, Kjell
    Radarbolaget, Gävle.
    Javashvili, Otar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Beckman, Claes
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    M-Sequence UWB Radar for Industrial Applications2010Ingår i: Program of GigaHertz Symposium 2010, March 9-10, at Lund University, 2010Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Ultra Wideband Radar has the potential of dramatically improving the control and surveillance of industrial processes in confined areas. An example is the application of UWB radar for surveillance of furnaces for heath treatment of steel billets developed by Radarbolaget in Gävle.

    In our installation at AB Sandvik Materials Technology, we have shown that by using a non-destructive UWB Radar technique it is possible to visualize in real-time the ongoing process inside the furnace behind a 0.5 m thick ceramic wall. Since the operating temperature inside the furnace is 1200 °C, there is today no other known method capable of visualizing the process for the operator of the furnace. The system is therefore designed to sustain high temperatures and powerful electromagnetic disturbances while performing measurement with wide dynamics and high stability.

    The design of this radar is based on the idea of transmitting a continuous m-sequence and then detecting the correlated impulse response (see figure below). The wide bandwidth is a requirement for obtaining high spatial accuracy and resolution but puts further requirements on the design of the antennas and the electronics. Our results show that with this technique it is possible to determine the deformation of the steel billets inside the furnace with an accuracy of less than 5 mm. The radar system is also able to detect deformations in the furnace wall

    The m-sequence radar has many advantages over other UWB radar technologies since it e.g. does not require many analogue components. Its performance is a result of the choice of code length, sampling rate and averaging. However, the resolution is still limited by the impulse response of the analogue antenna (ringing).

    In this paper system parameters that affect the overall performance of an m-sequence radar are reviewed and means of enhancing its performance are discussed.

  • 2.
    Beckman, Claes
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Center for RF-Measurement Technology2008Ingår i: Radio Science and Communication, RVK08, 2008Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    In February 2006 the Centre for RF Measurement Technology was established at the University of Gävle (HIG). The long term objectives of the centre are to establish world leading research in the area of RF Measurement Technology, support education of radio engineers for local, national and international radio companies at HIG, become a natural collaboration partner for leading industry companies and universities and to support local and national small and middle sized companies in the radio business.

    Today the centre has collaboration with more than 15 national and international companies within 3 major projects in the field of RF measurement technology research spanning from power amplifiers and antennas to electromagnetic interference in industrial environments.

    The annual research budget is in the area of 10 MSEK. In addition to the research projects the centre also supports education and collaboration with local industry, high schools and community.

    The centre is located easy to find, well equipped laboratories in Gävle Technology Park, next to the University of Gävle campus.

  • 3.
    Beckman, Claes
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Verifying 3G License Coverage Requirements2011Ingår i: Advances in Vehicular Networking Technologies / [ed] Miguel Almeida, InTech , 2011, s. 339-356Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    In the beginning of the 21’st century, the 3rd generation mobile phone systems, 3G, were introduced all around the world. In most countries, spectrum for this technology was allocated through some kind of licensing procedure. In Europe, the prevailing approach was to allocatespectrum through auctions, a process which led to a situation where the European operators found themselves committed to pay a staggering 130Bilion Euros for their 3G licenses.However, in most European countries, the fee was not the only obligation put on thelicensee: A coverage, “roll-out” requirement was in many cases also connected to the license(Northstream, 2002). Typically, these coverage requirements required that the licenseescover a certain area at a certain point in time after that the licenses had been awarded.In order for the regulators to verify that the licensees had met the coverage requirement and,hence, complied with the regulation, a method for coverage verification was needed. Suchmethods have therefore since then been developed by several European regulators (e.g. PTS2004; ECC 2007). In this book chapter we describe some general underlying consideration for the verification of radio coverage in UMTS systems and in particular we describe the Swedishmethodology developed by the Swedish Telecom regulator Post & Telestyrelsen (PTS).

  • 4.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Belkow, Elena
    Eklund, Lars
    Landmark, Urban
    Wirdemark, Per
    Verifying 3G License Requirements: some Preliminary Swedish Results2008Ingår i: The 68th IEEE Vehicular Technology Conference: VTC2008-Fall, 2008, s. 1-4Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In the year 2000, the Swedish Telecom regulator “Post&Telestyrelsen” (PTS) granted in a “beauty contest” four licenses for operation of 3G mobile networks. Through this process, the licensees committed themselves to cover 8.860.000 inhabitants of the Swedish population. In order to verify the coverage and confirm compliance with the license requirements, PTS, developed a test procedure in close collaboration with the licensees.

    The present paper gives an overview of the considerations behind the design of the test method and presents some preliminary results. Today all Swedish 3G operators comply with the licence requirement and it is concluded that a method for verifying the requirement accepted by the licensees is an important tool for successful licensing of spectrum and fulfilment of licensing obligations.

  • 5.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Eklund, Lars
    Karlsson, Bo
    Lindmark, Björn
    Ribbenfjärd, David
    Wirdemark, Per
    Verifying 3G licence requirements when every dB is worth a billion2006Ingår i: First European Conference on Antennas & Propagation: EuCAP 2006 / [ed] H. Lacoste & L. Ouwehand, 2006, s. 1-4Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the year 2000, the Swedish Telecom regulator: “Post&Telestyrelsen”, PTS, granted in a “beauty contest” four licenses for operations of 3G systems. To verify the coverage and the license requirements, PTS, has developed a test procedure where the field strength of the primary Common Pilot Channel, CPICH, is measured in a drive test. Designing such a test constitutes a number of challenges mainly due to the fact that in 3G the accuracy in the measurement needs to be extremely high since even a small systematic error of ~1dB could in Sweden have the consequence that each operator would have to build an extra +1000 sites at a staggering cost of ~1billion SEK!

    The present paper gives an overview of the considerations behind the design of the test method used for verification of the 3G licence requirements in Sweden.

  • 6.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Klahr, Stefan
    Ett ödesval för regionen2009Ingår i: Gefle Dagblad, Vol. 6 februariArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 7.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Lindmark, Björn
    Base station antennas for mobile communications2007Ingår i: 2007 IEEE International Symposium on Antennas and Propagation: Short Courses & Workshops, 2007Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    This course gives the participants a general overview of the application, implementation and design of current and future base station antennas for mobile communications. It is aimed at microwave, RF- and antenna engineers in the wireless area, but also useful for researchers looking for relevant research topics and system engineers needing a deeper understanding of the antenna component of their system. The course explains underlying theoretical and practical implementation aspects of base station antennas in mobile communication networks of today and the future.

    The course is divided into three main parts:

    (i) System Aspects,

    (ii) BTS Antenna Design,

    (iii) Diversity and MIMO

    In the first part the fundamental parameters of a base station antenna are discussed in the context of radio network design. In particular we discuss parameters such as gain, radiation patterns, frequency bands and power handling and put them in the context of cell planning, propagation and capacity.

    In the second part a general overview of base station antenna design is given. In particular the design aspects of radiators, feed networks and reflectors are discussed. Furthermore, a general discussion of array synthesis for base station antennas is given.

    In the final part of the course we give an overview of the underlying theory of diversity and MIMO systems. In particular we discuss the requirements that these systems put on the base station antennas in order to be able to deliver the data rates expected from WiMAX and the long term evolution of 3G systems.

  • 8.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Lindmark, Björn
    The evolution of base station antennas for mobile communications2007Ingår i: International Conference on Electromagnetics in Advanced Applications: ICEAA 07, 2007Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    During the last two decades, mobile telephony has virtually exploded around the world. Whereas fixed telephony has merely around 800 milion phone lines globally, cellular mobile telephony has today close to 4 bilion subscribers less than 20 years after the introduction of digital mobile telephony!

    In the centre of a mobile cell is the base station antenna whose vertical and horizontal beam pattern creates the borders. The first base station antennas deployed for cellular communications were omni-directional in the horizontal plane. These antennas are typically based on stacked circular dipole elements fed by a series feed network. However, as the need for capacity increased more radio channels were being used and the radio networks soon reconfigured to 3 sector systems. The base station antennas in these type of systems typically has half power beam widths in the horizontal plane of around 65 degrees and the elements are fed by corporate feed networks.

    Through the choice of antenna length and the selection of vertical element positions and excitations a broad range of antenna gains and vertical beam patterns can be achieved. We show that for a linear array the gain is mainly determined by the vertical and horizontal beam widths but reduced by losses in the feed network. The electrical down tilt is needed to provide good coverage within the desired cell and is preferred to mechanical down tilt as it is independent of horizontal angle. Remotely adjustable electrical down tilt is also available today and an important cost saver during the expansion part of a network. As we will see, system requirements on reduced channel interferencemlead to a simple expression for the necessary phase shift in such an array.

    Due to the rapid increase in subscribers it was soon realized by the regulators around the world that one frequency band for digital mobile communications was not enough to provide the capacity needed. Therefore, in the mid 90-ties second frequency bands were introduced in both North America and Europe. Since operators are not keen to put up bigger towers and more antennas, ´this development called for dual-band antennas. The introduction of the UMTS band in the beginning of this millennium of course then called for triple band functionality!

    Traditionally the diversity is achieved by using two receive antenna branches separated in space. In mobile phone networks, all base stations for macro cellular communications incorporate diversity on the up-link. Otherwise it would be virtually impossible to communicate with a low power mobile over the rapidly fading channel. Since space diversity uses two horizontally separate antennas positioned about 20 wavelengths apart it become soon of interest for the operators to incorporate polarization diversity. With polarization diversity only one dual polarized antenna is used for each sector at the base. In order to ensure good polarization diversity it is necessary and sufficient to have symmetrical patterns with equal power in horizontal and vertical polarization.

    In 3G it is of great interest to strengthen the up- and down-links in order to be able to increase the data rates from today’s 16kbit/s (voice) to a wireless broadband of around 10Mbits/s. However, in the Long Term Evolution of 3G, LTE, data rates of up to and around 100MBits/s are expected. In order accomplish this diversity at the base station will not be enough but complemented by multiple branch reception and transmission at both the base station and the mobile terminal (Multiple-Input-Multiple-Output, MIMO systems). For such arrays it is of interest to reduce the mutual coupling between elements. Although the mutual coupling could be compensated for by perfect channel estimation it is still of interest to reduce the coupling in practice in order to be able to handle the mismatch loss. In order to do so the use of e.g. corrugations, hard and soft surfaces as well as Electronic Band Gap, EBG materials for the inclusion into the antenna structure has been studied.

    In conclusion we find that the base station antenna has developed dramatically during the last two decades and base station antenna technology may become a key enabler for the Long Term Evolution of 3G.

  • 9.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Smith, Gregory
    Shared Networks: Making Wireless Communications Affordable2005Ingår i: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 12, nr 2, s. 78-85Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the wake of the substantial financial commitments incurred by European and other UMTS network operators in the form of licence fees, licensees have turned to network sharing as a means of reducing the capital requirements needed to bring 3G services to market. The reception from European regulators has been mixed, due to concerns that this inhibits competition, slow buildout, or otherwise result in reduced consumer benefits. The authors believe that the generic product life cycle model provides insights that indicate that network sharing, within an appropriately constructed regulatory framework, is not a threat to vigorous competition in the 3G industry, and in fact is one of the keys to stimulating the development of advanced, ubiquitous, affordable services.

  • 10.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Smith, Gregory
    Shared Networks: More than making wireless communication affordable2005Ingår i: Vehicular Technology Conference, 2005: VTC 2005-Spring., 2005, s. 2984-2988Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the wake of the substantial financial commitments incurred by European and other UMTS network operators in the form of license fees, licensees have turned to network sharing as a means of reducing the capital requirements needed to bring 3G services to market. The reception from European regulators has been mixed, due to concerns that this inhibits competition, slow build-out, or otherwise result in reduced consumer benefits. The authors believe that the generic product life-cycle model provides insights that indicate that network sharing, within an appropriately constructed regulatory framework, is not a threat to vigorous competition in the 3G industry, and in fact, is one of the keys to stimulating the development of advanced, ubiquitous, affordable services.

  • 11.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Smith, Gregory
    The Benefits of network Sharing2005Ingår i: Radiovetenskap och Kommunikation: RVK 2005, 2005, s. 147-151Konferensbidrag (Övrigt vetenskapligt)
  • 12.
    Händel, Peter
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle. Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Centre, Stockholm, Sweden.
    Prasad, Sathyaveer
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle. Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Centre, Stockholm, Sweden.
    Beckman, Claes
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Maximum likelihood estimation of reverberation chamber direct-to-scattered ratio2009Ingår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 45, nr 25, s. 1285-1286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The exact maximum likelihood estimator of the direct-to-scattered ratio of the Rician channel in a reverberation chamber is derived and its performance analysed. It is shown that the estimator obeys a non-central F-distribution, the mean value and variance of which are derived. For well stirred chambers, it is shown that the systematic error in the estimated ratio may be significant.

  • 13.
    Ikram, Amna
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Beckman, Claes
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Irmscher, Stefan
    Laird Technologies.
    Design and Development of a Multiband Loop Antenna for Cellular Mobile Handsets2011Ingår i: IEEE International Workshop on Antenna Technology, 2011, s. 251-254Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the results of the design and characterization of a loop antenna for mobile cellularh andsets. Based on a typical smart phone antenna geometry, a bottom mounted off-ground meanderline loop antennah as been designed, which has the potential to cover the required bands of Long Term Evolution (LTE) US 700MHz, Global System for Mobile communications (GSM) 824-960MHz, Digital Communication System (DCS) 1710-1880 MHz, Personal Communication Services PCS 1850-1990 MHz, Universal Mobile Telecommunications System (UMTS) 1920-2170MHz and LTE EU 2500. The carrier volume of 50*10*5mm3 and ground plane of length 100mm is used. The carrier permittivity εr is 2.66 and loss tangent tanδ is 0.00629 @2.44GHz. Copper is used as a metal part of the antenna having conductivity of 5.8e7 S/m and thickness of 0.1mm. The antenna supports balanced and unbalanced modes for certain frequencies. It is highly efficient in terms of small volumetric size for a given bandwidth of operations. The antenna generates weak near field electric and magnetic fields complying with the standards for the Specific Absorption Rate (SAR) and Hearing Aid Compability (HAC). The impact of body effects on the radiation efficiency has been quantified. The measured results of the prototype are in good agreement with the simulated results.

  • 14.
    Krishna, Pothula Hari
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Cánovas, Victor
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Ramachandran, Prasadh
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Beckman, Claes
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Multi-band PIFA for combined 3G and DVB-H Terminals: a preliminary study2007Ingår i: 2007 IEEE International Workshop on Antenna Technology: Small & Smart Antennas, Metamaterials and Applications : iWAT 2007, S²AMA : conference proceedings : Cambridge, UK, March 21-23, 2007, Piscataway, NJ: IEEE , 2007, s. 439-442Konferensbidrag (Refereegranskat)
    Abstract [en]

    Based on the work by Ciais et. al, a small, efficient and low profile Planar Inverted-F antenna with multi-band operations for the use in mobile telephones has been studied. The antenna was designed using a High Frequency Structure Simulator, HFSS, built and verified. In order to increase the bandwidth of the antenna from the original design it is further optimized by frequency tuning using the shorts of different parasitic element. The resulting antenna operates over two wide bands from (710-1200) MHz and from (1750-2170) MHz, covering five cellular bands and the upper part of the UHF-band allowing it to be used in terminals combining cellular and DVB-H operations.

  • 15.
    Prasad, Sathyaveer
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Beckman, Claes
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Comparison of Four Different Methods to Estimate the Radiated Power from Mobile Phones2010Ingår i: 2010 Loughborough Antennas and Propagation Conference, LAPC 2010, 2010, s. 425-428, artikel-id 5666216Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In this paper, the radiated power is estimated for various commercially available mobile phones using the Telia Scattered Field Measurement method (TSFM), In-Network performance estimation and the EMSCAN near field scanner: "Lab-Express". The results are then compared with the radiated power measured using the Satimo Star Gate 64/24 system. Our measurement results suggest that the radiated power measured in the TSFM method correlates to a great extent both with the Star Gate System and the In-network method suggesting that the TSFM method can be used an alternative tool to in-network measurements and also can be used for standard reference measurements provided accuracy and repeatability are accounted according to the standards. However, the results from the Star Gate system were weakly correlated to the results from the Lab-Express suggesting that Lab-Express cannot replace Star Gate System for standard reference measurements but can only serve as a good tool for testing antennas during design and development phases.

  • 16.
    Prasad, Sathyaveer
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Medawar, Samer
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Beckman, Claes
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Estimation of the Rician K-factor in Reverberation Chambers for Improved Repeatability in Terminal Antenna Measurements2008Ingår i: 30th Annual Symposium of the Antenna Measurement Techniques Association (AMTA), Boston, Mass.: AMTA-2008 , 2008, s. 6-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The in-network performance of the mobile phone depends highly on the terminal antennas. Their performance may reduce the coverage and the capacity of the whole network. Hence, an antenna measurement method that accurately emulates the in-network radio environment is much desired.

    The reverberation, or mode-stirred, chamber is a cavity resonator with a high Q factor used for testing the performance of terminals and terminal antennas in a controlled field environment. In order to create a homogeneous field inside the chamber, emulating an isotropic multipath environment, mode stirrers are used.

    The Rician K-factor is a statistical parameter that describes the field distribution in the chamber and is defined as the ratio of the unstirred to stirred field components in the chamber. This K-factor varies from zero to infinity. In order to be able to accurately repeat a measurement performed in a reverberation chamber it is, hence, of greatest importance to accurately determine the Rician K-factor from said measurements.

    In this paper, a statistical model for the electromagnetic fields in reverberation chamber is reviewed for a Line of Sight (LOS) environment. An Estimator of the Rician K-factor is derived and its accuracy is verified.

  • 17.
    Prasad, Sathyaveer
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Ramachandran, Prasadh
    Glazunov, Andres Alayon
    Beckman, Claes
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    EVALUATION OF THE TELIA SCATTERED FIELD MEASUREMENT METHOD FOR ESTIMATION OF IN-NETWORK PERFORMANCE OF MOBILE TERMINAL ANTENNAS2007Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In this paper we present and evaluate a method for estimation of in-network performance of mobile terminal antennas developed by the Swedish telecom operator Telia.

    The Telia Scattered Field Measurement (TSFM) Method is intended to give a better estimate of the performance of the mobile terminal antenna as in an in-network fading scenario. The parameter measured from the TSFM method is referred to as the Scattered Field Measurement Gain, SFMG, i.e. the Mean Effective Gain, MEG, measured relative to a half wave dipole antenna. MEG includes the radiation pattern of the mobile terminal antenna as well as an estimate of polarization and directional losses that occur due to the propagation environment.

    In this study it is found that the TSFM method provides a good measure of the in-network performance of the mobile terminal antenna. Furthermore, it is shown that the SFMG measured with this method is found to be well correlated with the Total Radiated Power Gain, TRPG, or radiation efficiency. This suggests that the Total Radiated Power, TRP, may be a good measure of the in-network performance of mobile terminal antennas if measured with proper adjustment to the antenna and propagation channel mismatch.

  • 18.
    Ramachandran , Prasadh
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Bengtsson , Olof
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Beckman, Claes
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Impedance determination of terminal power amplifiers for optimal antenna matching using load-pull method2009Ingår i: 2009 IEEE International Workshop on Antenna Technology: iWAT2009 : "Small Antennas and Novel Metamaterials", Santa Monica, California, 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present a single tuner based load-pull method for characterization of optimal antenna load impedance in mobile terminals. In the proposed load-pull set-up the mobile terminal itself is used as a source. The presented method can provide valuable data for antenna design since it determines the optimal impedance at the antenna connector/pad taken into account the full output circuitry of the mobile terminal. It reveals the modification of the power amplifier, PA, output impedance caused by the presence of saw filter, antenna switch, and transmission line possibly present between the PA and the antenna. With the presented method it is not only possible to characterize the optimum antenna impedance to present to the terminal in different bands and channels but also to reveal the impedance miss-match sensitivity for each channel.

  • 19.
    Ramachandran, Prasadh
    et al.
    Pulse Finland Oy.
    Milosavljevic, Z
    Pulse Finland Oy.
    Beckman, Claes
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Adaptive penta-band handset antenna with hand effect compensation2012Ingår i: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, E-ISSN 1751-8733, Vol. 6, nr 1, s. 79-86Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The increase in the number of cellular operating bands and the ever-increasing criteria antenna size reduction has pushed the need to use switchable antenna structures. Further, the presence of a hand in the close vicinity of the antenna causes deterioration in performance. The authors present a switchable antenna technique, evaluate the effect of the human hand on it and discuss a novel method to compensate for the mismatch. A penta-band switchable planar inverted-F antenna covering 824-960 and 1710-2170-MHz has been used in this study. The presence of the hand was observed to cause 2.0-6.0-dB loss in efficiency for the low band. Using the proposed extra-ground antenna switching method and the dynamic antenna matching, technique the total efficiency of the antenna can be improved by 0.5-2.5-dB compared to the mismatched case.

  • 20.
    Ramachandran, Prasadh
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Milosavljevic, Zlatoljub
    Beckman, Claes
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Adaptive Matching Circuitry for Compensation of Finger Effect on Handset Antennas2009Ingår i: EuCAP 2009: 3rd European Conference on Antennas and Propagation, Berlin, 2009, s. 801-804Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present and evaluate the effect of hand on terminal antenna and discuss a method to compensate for the mismatch. A dual band PIFA was used in this study. The presence of the hand was observed to cause 2-6dB loss in efficiency in low-band and 2-4dB loss in highband.In this study we propose a dynamic antenna matching (DAM) technique to improve matching level that can improve the total efficiency of the antenna by 2 – 4dB compared to the mismatched case.

  • 21.
    Zhao, Hai
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Lin, Gui
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Claes, Beckman
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Design of a Coupling Element Based Penta-band Mobile Phone Antenna2009Ingår i:  Antennas & Propagation Conference, 2009. LAPC 2009. Loughborough, 2009, s. 209-212Konferensbidrag (Refereegranskat)
    Abstract [en]

    Based on the work by Vilanen et al., a small, low profile and efficientcoupling element based antenna with penta-band operations for the use inmobile telephones has been studied. The antenna was designed using the HighFrequency Structure Simulator, HFSS, from Ansoft. Two prototypes withdifferent antenna profile heights have been built, verified and tested. Thebandwidth of the antenna is extended compared to the original design. Alumped element based network is used to optimize the matching. Theresulting antenna operates (|S11|≤-5 dB) from 824 to 1300MHz and from1710 to 2170MHz, covering in total five cellular bands with an efficiencybetter than -3dB and a total volume of less than 4cm3.

1 - 21 av 21
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