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  • 1.
    Andersen, O.
    et al.
    Ericsson AB.
    Wisell, David
    Ericsson AB.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Measurement of ACLR with high dynamic range2008In: IEEE MTT-S International Microwave Symposium Digest, Atlanta, GA, 2008, p. 273-277Conference paper (Other academic)
    Abstract [en]

    In this paper a method to overcome the insufficient dynamic range of RF measurement instruments, i.e. signal generators and spectrum analyzers, for distortion measurements on feedforward and other highly linear amplifiers, is discussed. A circuit board is designed, built and verified. Its performance is found to be superior to traditional methods using filters, both from a technical performance and flexibility standpoint as well as from an economic view. ACLR measurements for WCDMA signals can be done well below -70 dBc using the produced circuit board. © 2008 IEEE.

  • 2.
    Andersen, Olav
    et al.
    Ericsson.
    Björsell, Niclas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    A Test-Bed Designed to Utilize Zhu’s General Sampling Theorem to Characterize Power Amplifiers2009In: Instrumentation and measurement technology conference 2009 I2MTC '09 IEEE, Singapore, 2009, p. 201-204Conference paper (Refereed)
    Abstract [en]

    Characterizing power amplifiers require test set-ups with performance superior to the power amplifiers. A commonly used method is to use an IQ-demodulator. However, problem arises due to imperfections in the demodulator such as IQ-imbalance; an alternative method is to use a direct down converter to intermediate frequency. The drawback then is the limited bandwidth. However, the required bandwidth of the ADC does not need to be exceptional. According to Zhu’s general sampling theorem is it enough to sample the output signal at the Nyquist rate of the input. However, even though the required sampling rate is reduced the demands on the analog bandwidth remains. Unfortunately, commercially available instruments such as vector signal analyzers can not be used for this purpose since their analog bandwidth is too small. In this paper a test-bed is designed to utilize the Zhu’s general sampling theorem. The RF front-end has frequency range of 500 MHz – 2.7 GHz and a bandwidth of 1 GHz. All performance data are verified with measurements.

  • 3.
    Andersen, Olav
    et al.
    Ericsson Telecom AB, Gävle, Sweden.
    Wisell, David
    Ericsson Telecom AB, Stockholm, Sweden.
    Staenvard, Patrik
    Ericsson Telecom AB, Gävle, Sweden.
    Keskitalo, Niclas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Extending the Bandwidth and Dynamic Range of Old RF Instruments to Meet State-of-the-Art Performance, Using a Synthetic Instrument Approach2009In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 58, no 2, p. 248-254Article in journal (Refereed)
    Abstract [en]

    A decrease in life cycle cost is a key issue for testing mobile communication systems. The rapid development and edge technology requires high-performance instruments and state-of-the-art measurement technology. New investments are expensive, but even older generation instruments are capable of extending their bandwidth and dynamic range to meet even the latest Third-Generation Partnership Project (3GPP) cellular measurement requirements by the addition of external hardware using a synthetic instrument approach. The novelty of this paper is the high performance on the most crucial parameters, i.e., the dynamic range and bandwidth achieved by only replacing some parts of the legacy instrument. Moreover, the demonstrated direct IF synthesis has a high degree of novelty at wide modulation bandwidths. It is desired to use virtual/synthetic instruments and make the signal processing in the software independent of the hardware, i.e., software-defined measurements (SDMs). In this paper, a state-of-the-art experimental setup for signal generation and signal analysis is demonstrated. A direct IF synthesis is used to generate a wideband code-division multiple-access (WCDMA) carrier with more than 72-dB adjacent carrier leakage ratio (ACLR) up to 12 parallel carriers with more than 68-dBc ACLR over a total bandwidth of 100 MHz. The signal analysis capabilities (e.g., ACLR performance) for a WCDMA carrier is better than -70 dBc and for a continuous wave better than -85 dBc over a bandwidth of 42.5 MHz. The critical RF downconverter in the setup is carefully designed not to degrade the dynamic range performance.

  • 4.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Daponte, Pasquale
    Department of Engineering, University of Sannio, Italy.
    De Vito, Luca
    Department of Engineering, University of Sannio, Italy.
    Rapuano, Sergio
    Department of Engineering, University of Sannio, Italy.
    Automatic signal recognition for a flexible spectrum management2009In: XIX IMEKO World Congress, 2009, p. 568-573Conference paper (Refereed)
    Abstract [en]

    The paper presents the prototype of an automatic digital modulation classifier, to be used for signal recognition in frequency bands managed in a flexible way. The prototype is based on a Data Acquisition System, consisting of an Analog-to-Digital converter embedded in an evaluation board, a frame grabber and a Personal Computer. The modulation classifier is able to recognize the most used digital modulations. An experimental validation of the realized prototype in a radio environment is also provided.

  • 5.
    BUCCARDO, ALDO
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    A SIGNAL DETECTOR FOR COGNITIVE RADIO SYSTEM2010Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    The communication systems are changing. Cognitive Radio is an automatic adaptative system to improve the spectrum efficiency. It has intelligence to adapt itself to the environment to improve the transmission performancies. For this system, spectrum sensing function is very important so a signal detector is necessary. In this work a signal detector has been implemented in GNU Radio environment. GNU Radio is a platform that respects the Cognitive Radio aproach. It is flexible, software defined and cheap.

  • 6.
    Fraz, Hamza
    et al.
    Georgia Tech..
    Björsell, Niclas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Kenney, J. S.
    Georgia Tech..
    Sperlich, R.
    Texas Instruments.
    Prediction of Harmonic Distortion in ADCs using dynamic Integral Non-Linearity model2009In: Behavioral Modeling and Simulation Workshop, 2009. BMAS 2009. IEEE, 2009, p. 102-107Conference paper (Refereed)
    Abstract [en]

    This paper investigates the application of dynamic, Integral Non-Linearity (INL) model of Analog-to-Digital Converters (ADC) to predict the harmonic distortion in pipelined ADCs. The device used to validate the model is Texas Instruments' ADS6129; a 12-bit, 250 MSPS1 pipelined ADC. The performance of the model is measured using single tones in the first Nyquist zone, with an amplitude ranging between −1 dBFS2 and −46 dBFS. Total Harmonic Distortion (THD) and Spurious Free Dynamic Range (SFDR) are used as metrics to compare the performance of the model to the actual ADC. The results indicate that a model for High Code Frequency (HCF) INL is essential for correct prediction of distortion for input signals with small amplitudes. The results also suggest that dynamic INL models offer an effective method to model the distortion in ADCs until Nyquist frequency only. Beyond Nyquist frequency, the non-linear effects of Track and Hold (T/H) start manifesting and the INL model can no longer account for all the distortion seen at the output of ADCs.

  • 7.
    Händel, Peter
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies. Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Centre, Stockholm, Sweden.
    Prasad, Sathyaveer
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies. Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Centre, Stockholm, Sweden.
    Beckman, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Maximum likelihood estimation of reverberation chamber direct-to-scattered ratio2009In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 45, no 25, p. 1285-1286Article in journal (Refereed)
    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.

  • 8.
    Javashvili, Otar
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment.
    UWB Antennas for Wall Penetrating Radar Systems2009Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Basic properties and new design principles of ultra wideband Vivaldi antennas are presentedand discussed in this paper. The focus will be on the modeling of Vivaldi antenna design curves, by which it is constructed; its simulation results, realization and the measurements.

    According to the aim of this research the discussion starts with the review of the previous researches done for Vivaldi antennas. Introductory part of the report also contains the problem description for the current project and the classification of the goals to be achieved. As a theoretical review, the discussion initiates with the definitions anddescription of basic parameters of the antennas and covers a short presentation of UWBpulse-based radar system. The attention will be focused on UWB signals behavior and characterization, their propagation principles and basic troubles stands nowadays. As anapplication the wall penetrating Radar systems will be considered. The major part of thereport holds on the investigation of the design principles of Vivaldi Antenna andoptimization of the key parameters for achieving the best performance for radar. Theending part of the report shows the simulations and measurement results and theircomparisons following with conclusions/discussions.

    The report will be supportive for the antenna designers, who work for UWB systems andparticularly for Vivaldi antennas, as long as there are showing up detailed descriptions ofVivaldi antenna characteristics depending on its shape and substrate properties. The modelfor designing Vivaldi antennas, given in this project, can successfully be applied for almostall the cases used in practice nowadays.

  • 9.
    Landin, Per
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Isaksson, Magnus
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Keskitalo, Niklas
    University of Gävle, Center for RF Measurement Technologies.
    Tornblad, Olof
    Infineon Technologies.
    Sideband asymmetries in RF Power LDMOS Before and After Digital Predistortion2009Conference paper (Other academic)
    Abstract [en]

     The merging of the fields of RF engineering and signal processing has introduced concepts such as behavioral modeling and enabled digital linearization schemes for wireless devices, such as power amplifiers (PAs). Despite that this process has been going on for a number of years much work remains to be done. The links between physical behavior and mathematical models are far from well-understood as are the optimum strategies for device design. This study focus on digital predistortion properties of a one-stage PA consisting of a power transistor mounted in a test fixture. The device under test (DUT) is an Infineon PTF210451E, a 45W transistor intended for usage in the frequency bands 2010-2025 MHz and 2110-2170 MHz. The test fixture is also designed by Infineon Technologies.  The signal types used in the measurements are single and double carrier wideband code division multiple access (WCDMA) signals. The double carrier WCDMA signals have tone-spacings of 5, 10 and 15 MHz. Normal two-tone measurements are also presented. 

  • 10.
    Landin, Per Niklas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Isaksson, Magnus
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies.
    Tornblad, Olof
    A Study of memory effects of RF power LDMOS before and after digital predistortion2009In: Wireless and Microwave Technology Conference, 2009. WAMICON '09. IEEE 10th Annual, 2009, p. 1-5Conference paper (Refereed)
    Abstract [en]

    Sideband asymmetries in distortion products are created due to electrical and thermal memory effects and this can be difficult to correct for in a digital predistortion algorithm. In this study, sideband asymmetries in third-order intermodulation distortion products before and after digital predistortion were investigated using 2-tone and 2-carrier WCDMA signals. The parallel Hammerstein (PH) model was used in the digital predistortion algorithm. The sign of the asymmetries before correction were found to depend on power level. Memoryless correction lead to an increase in asymmetries for some power ranges whereas using a PH model of order 13 with only one order of memory length lead to good correction over a large power range.

  • 11.
    Landin, Per Niklas
    et al.
    University of Gävle, Center for RF Measurement Technologies.
    Nader, Charles
    University of Gävle, Center for RF Measurement Technologies.
    Björsell, Niclas
    University of Gävle, Center for RF Measurement Technologies.
    Isaksson, Magnus
    University of Gävle, Center for RF Measurement Technologies.
    Wisell, David
    Ericsson AB.
    Händel, Peter
    University of Gävle, Center for RF Measurement Technologies.
    Andersen, Olav
    Ericsson AB.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies.
    Wideband Characterization of Power Amplifiers Using Undersampling2009In: 2009 IEEE MTT-S International Microwave Symposium, Boston: IEEE MTT , 2009, p. 1365-1368Conference paper (Refereed)
    Abstract [en]

    In this paper a radio frequency power amplifier is measured and characterized by the use of undersampling based on the generalized Zhu-Frank sampling theorem. A test system has been designed allowing the bandwidth of the stimuli signal to be 100 MHz in the characterization process. That would not be possible with any vector signal analyzer on the market. One of the more challenging problem within the proposed concept is the model validation process. Here, two different techniques for model validation are proposed, the multitone and the spectrum scan validation methods.

  • 12.
    Miranda, Juan
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Gidlund, Mikael
    Coded OFDM in hybrid radio over fibre links2008In: GigaHertz Symposium 2008: Abstract Book, Göteborg: Chalmers , 2008, p. 16-16Conference paper (Other academic)
    Abstract [en]

    Distributed antenna systems based on Radio over Fiber (RoF) has proofed to be the most efficient solution to achieve in-building coverage in 3G systems [1]. Today 3G uses an air interface based on WCDMA. However, Coded Orthogonal Frequency Division

    Multiplexing (COFDM), has been selected in IEEE802.11a, WiMax and the long term evolution of 3G (LTE) due to its flexibility and robustness in fading environments [2].

    The objectives of the present investigation are therefore to examine the OFDM reliability in the nonlinearities and multipath posed by the RoF link, and how its performance can be improved by using representative linear block codes.

    As a measure of reliability, the Bit Error Rate (BER) of the uncoded and coded OFDMRoF system for Uplink (UL) and Downlink (DL) was simulated. The system modeling

    considers multipath fading from radio transmission [3] and Amplitude-to-Amplitude (AM/AM) and Amplitude-to-Phase (AM/PM) distortions produced by the Electrical-to-

    Optical (E/O) conversion and amplifying stages of the fiber link [4]. Several BCH and Reed-Solomon codes were studied with different code rates [5], complexity and interleaving depth. Their properties are related to system parameters such as Bit Energy

    per Noise Density, Input Back-Off (IBO) and modulation order.

    The Results show that using 4-QAM modulation with a moderate Input Back-Off (i.e. 4- 10dB), BCH and small Reed-Solomon codes can reduce BER by a factor even greater

    than 10 depending on the IBO. However, using 16-QAM modulation BER reduction is poor even if Reed-Solomon is used with large number of bits per symbol.

    Future work would consider using a more complex model for the E/O conversion and power amplifier, more sophisticated codes such as Turbo or LDPC, and the use of nonlinear channel

    estimation to further enhance system performance.

  • 13.
    Nader, Charles
    et al.
    University of Gävle, Center for RF Measurement Technologies.
    Altahir, Hibah
    University of Gävle, Center for RF Measurement Technologies.
    Andersen, Olav
    Ericsson AB.
    Björsell, Niclas
    University of Gävle, Center for RF Measurement Technologies.
    Condo, Edith
    University of Gävle, Center for RF Measurement Technologies.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies.
    De La Rosa, Hector
    Freescale Semiconductor Nordic AB.
    Automated multidimensional characterization of power amplifier for design and production2009In: 2009 IEEE Instrumentation and Measurement Technology Conference Proceedings, Singapore: I&M Society , 2009, p. 144-148Conference paper (Refereed)
    Abstract [en]

    Designing, optimizing and producing modern power amplifiers (PA) requires new and fast RF (radio frequency) measurement techniques capable of characterizing its real behavior. Power amplifiers are a truly multidimensional device where many desired performance parameters are contradictory to each other. This is especially true for the generation of modern communication PAs that require high efficiency, high linearity as well as high bandwidth. This paper presents a software-defined measurement setup for fast and cost efficient multidimensional measurements based on highly accurate standard instruments and a PC. The test bed as well as the graphical user interface is presented along with a demonstration of its functionality. During tuning of tank networks, drain quiescent current, and bias conditions, 3-dimensional graphs can be selected for the most appropriate axes of trade-off parameters to display a true behavior of the PA under test subjected to real-world or close to real-world signals. The measurement system offers the possibility to monitor envelope-tracking dynamic power consumption up to 100 MHz plus the possibility to use high crest factors.

  • 14.
    Nader, Charles
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Landin, Per Niklas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Björsell, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Isaksson, Magnus
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Wisell, David
    Ericsson AB.
    Händel, Peter
    KTH, EES, Signal processing lab.
    Andersen, Olav
    Ericsson AB.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies.
    Wideband Power Amplifiers Characterization by Undersampling: Zhu-Frank Sampling Theorem2009Conference paper (Other academic)
  • 15.
    Prasad, Sathyaveer
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Halim, Humam
    Beckman, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Evaluation of a Near Field Scanner for TRP and Radiation Pattern Measurements of GSM Mobile Phones2009In: 3RD EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, IEEE conference proceedings, 2009, p. 2122-2126Conference paper (Other academic)
    Abstract [en]

    In this paper a new tool for estimation of the radio performance of terminal antennas in terms of Total Radiated Power, TRP is tested and evaluated. The tool is known as Lab Express and is developed by the Canadian company EMSCAN.  The results from measurements performed with the Lab Express are compared with of the radiation patterns and total radiated power (TRP) estimates, measured with a CTIA approved Satimo SG24 chamber.

    The TRP and radiation pattern measurements are performed on 10 commercially available mobile phones at GSM 900 and GSM 1800 frequency bands. The dependency of the measured TRP on the positioning of the mobile phone on EMSCAN is also tested. Our results indicate that the TRP measured with Lab Express is well correlated with the results obtained from the Satimo SG24 chamber even though the Lab Express equipment seem to over estimate the TRP with on average about 4dB at 900MHz and about 1.3dB at 1800MHz.

  • 16.
    Prasad, Sathyaveer
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Ramachandran, Prasad
    University of Gävle, Center for RF Measurement Technologies.
    Mean Effective Gain Measurements of Mobile Phones using the Telia Scattered Field Measurement Method2007In: RFMTC07: The Conference on RF Measurement Technology for State of The Art Production and Design, Stockholm: KTH , 2007, p. 7-Conference paper (Other academic)
    Abstract [en]

    In this paper, the measurement procedure for estimation of mobile phone antenna performance is presented. This is achieved by considering the Mean Effective Gain (MEG) relative to half-wavelength dipole antenna as the figure of merit. MEG of 13 commercially available mobile phones is measured using the Telia Scattered Field (TSFM) Method in one channel at each of the GSM900 and DCS1800 bands. The measurements of these handsets are carried out in Rayleigh fading environment, characterized by the XPR obtained from the propagation measurements. The statistics of the measured envelope distribution have been fitted to Rayleigh, Rice and Weibull distributions with corresponding goodness of fit analysis. Further, the investigation focuses on the variation of MEG with the surrounding environment of propagation and also with the position of the mobile phone.

  • 17.
    Prasad, Sathyaveer
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Ramachandran, Prasadh
    Glazunov, Andres Alayon
    Beckman, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    EVALUATION OF THE TELIA SCATTERED FIELD MEASUREMENT METHOD FOR ESTIMATION OF IN-NETWORK PERFORMANCE OF MOBILE TERMINAL ANTENNAS2007Conference paper (Other academic)
    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.
    Qureshi, Rustam Mustafa
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Ring Resonator with single gap for Measurement of Dielectric Constants of Materials2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The significance of calculating and measuring dielectric constant is important for all the fields of study and research from biological science to electronics and telecommunication. It gives a better characterization of the material and helps to design the accurate system, and aside these two functions, it has numerous uses. Owing to its huge expediency, various measurement methods of dielectric constant of materials have been developed by scientists and engineers over the years. Each method has its limitations which affect the accuracy of the measurement; these limitations range from frequency, temperature, measurement environment to material under test.

    In this research work, we measured the resonant frequency of the ring resonator using different materials and then we measured the dielectric constant of different materials by using that resonant frequency. We discussed different common methods of measuring dielectric constant and the most accurate one, the resonant method, was chosen and driven upon .The project was done by making a mathematical analysis for the geometry of the ring resonator, wrote MATLAB script for the measurement of the resonant frequency, later designed and simulated in HFSS to obtain results which would be comparable to ones obtained in laboratory measurements.

    The ring was fabricated and taken to the laboratory for measurement of the resonant frequency for measuring dielectric constant of different materials; two monopole antennae were connected to the two ports of a vector network analyzer with one antenna serving as the transmitter and the other serving as the receiver. When we used the MUT in the gap of the ring resonator we saw frequency shift in the resonant frequency and we noted that resonant frequency.

    The resonant frequencies obtained were compared with the geometric parameters of the ring resonator and that of the MUT in an equation written into MATLAB script; this equation was used to extract the dielectric constant of the MUT and then we calculated the dielectric constant by using the resonant frequency of the MUT.

  • 19.
    Ramachandran , Prasadh
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Bengtsson , Olof
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Beckman, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Impedance determination of terminal power amplifiers for optimal antenna matching using load-pull method2009In: 2009 IEEE International Workshop on Antenna Technology: iWAT2009 : "Small Antennas and Novel Metamaterials", Santa Monica, California, 2009Conference paper (Refereed)
    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.

  • 20.
    Ramachandran, Prasadh
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Method and Arrangement for Matching an Antenna2008Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A method and an arrangement for matching the antenna of a radio device in transmitting condition. The antenna impedance in the output of the power amplifier of a transmitter is adjusted by means of a π-shaped reactive matching circuit, the component values of which can be selected from a relatively wide array of the alternatives. The component values are selected by means of the multiple-way switches, which only are located in the transverse branches of the matching circuit. The switches are set (706) by the control unit, input variables of which being the SWR value provided by the directional coupler, the operating band used each time and a value of the transmitting power. The matching is based on an adjusting process to be executed at regular intervals, in which process the control unit tries different combinations of the switch states and finally selects (710) the combina¬ tion, which brings the lowest SWR value. In the beginning of the adjusting process the control unit reduces (705), on grounds of the current values of the input variables, the number of the combinations to be tried. The antenna matching maintains relatively good, although the internal output impedance of the amplifier and the impedance from the output towards the antenna would strive to differ from each other for external reasons, a band changing or a change in the outptut power.

  • 21.
    Ramachandran, Prasadh
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Milosavljevic, Zlatoljub
    Beckman, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Adaptive Matching Circuitry for Compensation of Finger Effect on Handset Antennas2009In: EuCAP 2009: 3rd European Conference on Antennas and Propagation, Berlin, 2009, p. 801-804Conference paper (Refereed)
    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.

  • 22.
    Stenumgaard, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Radiated Emission from Personal Computers: a Safety Risk for TETRA Systems?2008In: 2008 International Symposium on Electromagnetic Compatibility - EMC Europe, IEEE , 2008, p. 1-3Conference paper (Refereed)
  • 23.
    TESHOME, ABIY TEREFE
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    FPGA based Eigenvalue Detection Algorithm for Cognitive Radio2010Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Radio Communication technologies are undergoing drastic demand over the past two decades. The precious radio resource, electromagnetic radio spectrum, is in vain as technology advances. It is required to come up with a solution to improve its wise uses.

    Cognitive Radio enabled by Software-Defined Radio brings an intelligent solution to efficiently use the Radio Spectrum. It is a method to aware the radio communication system to be able to adapt to its radio environment like signal power and free spectrum holes. The approach will pose a question on how to efficiently detect a signal.

    In this thesis different spectrum sensing algorithm will be explained and a special concentration will be on new sensing algorithm based on the Eigenvalues of received signal. The proposed method adapts blind signal detection approach for applications that lacks knowledge about signal, noise and channel property. There are two methods, one is ratio of the Maximum Eigenvalue to Minimum Eigenvalue and the second is ratio of Signal Power to Minimum Eigenvalue.

    Random Matrix theory (RMT) is a branch of mathematics and it is capable in analyzing large set of data or in a conclusive approach it provides a correlation points in signals or waveforms. In the context of this thesis, RMT is used to overcome both noise and channel uncertainties that are common in wireless communication.

    Simulations in MATLAB and real-time measurements in LabVIEW are implemented to test the proposed detection algorithms. The measurements were performed based on received signal from an IF-5641R Transceiver obtained from National Instruments.

     

  • 24.
    Zhao, Hai
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Gui, Lin
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Penta-Band Coupling Element Based Mobile Phone Antenna2009Book (Other academic)
    Abstract [en]

    This thesis presents a study on built-in type low profile and low volume mobile phone antennas. In a coupling element based antenna, the chassis is the main radiator and the antenna elements are the exciters for the wave modes at low frequency. The main work of this thesis is to demonstrate and investigate the performance of the coupling element based antenna and study a variety of cases with different physical lengths and different physical heights. The investigation is done by using simulators. The performance is evaluated by analyzing the impedance bandwidth and the efficiency. For the study, antenna prototypes integrating miniaturized matching circuits were modeled. Two antenna structure prototypes were manufactured and measured. The Measured results are presented and compared with simulations. Finally, the performance of the coupling element based antenna is compared with planar inverter-F antenna (PIFA) and discussed.

  • 25.
    Zhao, Hai
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Lin, Gui
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Claes, Beckman
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Design of a Coupling Element Based Penta-band Mobile Phone Antenna2009In:  Antennas & Propagation Conference, 2009. LAPC 2009. Loughborough, 2009, p. 209-212Conference paper (Refereed)
    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 - 25 of 25
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