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Antenna Load

The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform

Martin Štumpf – 1st expert on this subject based on the ideXlab platform

  • The Time-Domain Compensation Theorem and Its Application to Pulsed EM Scattering of Multiport Receiving Antennas
    IEEE Transactions on Antennas and Propagation, 2020
    Co-Authors: Martin Štumpf

    Abstract:

    The time-domain (TD) compensation theorem concerning a general $N$ -port Antenna system is derived with the aid of the reciprocity theorem of the time-convolution type. The compensation theorem describes the impact of a change in the Antenna Load matrix on receiving-Antenna-scattering properties. As such, the obtained results can serve as the basis for tailoring the pulsed echo of Loaded scatterers or for understanding the limitations of Thevenin’s and Norton’s Antenna equivalent circuits. Illustrative numerical examples concerning both linear and nonlinear Antenna Loads validate the TD compensation theorem.

  • The Time-Domain Compensation Theorem and Its Application to Pulsed EM Scattering of Multiport Receiving Antennas
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Martin Štumpf

    Abstract:

    The time-domain (TD) compensation theorem concerning a general N-port Antenna system is derived with the aid of the reciprocity theorem of the time-convolution type. The compensation theorem describes the impact of a change in the Antenna Load matrix on receiving-Antenna-scattering properties. As such, the obtained results can serve as the basis for tailoring the pulsed echo of Loaded scatterers or for understanding the limitations of Thévenin’s and Norton’s Antenna equivalent circuits. Illustrative numerical examples concerning both linear and nonlinear Antenna Loads validate the TD compensation theorem.

  • Controlling pulsed EM scattering of receiving Antennas: The one-port case
    2016 URSI International Symposium on Electromagnetic Theory (EMTS), 2016
    Co-Authors: Martin Štumpf

    Abstract:

    A time-domain compensation theorem concerning EM scattering of a one-port Antenna system is derived with the aid of the reciprocity theorem of the time-convolution type. The theorem describes the impact of a change in the Antenna Load on receiving-Antenna scattering properties. Applications of the theorem are found in controlling the pulsed echo of a receiving Antenna as well as in related theoretical aspects of receiving-Antenna scattering theory.

A. Chockalingam – 2nd expert on this subject based on the ideXlab platform

  • VTC Spring – Load Modulated Arrays Using Channel Modulation with RF Mirrors
    2019 IEEE 89th Vehicular Technology Conference (VTC2019-Spring), 2019
    Co-Authors: Sandeep Bhat, A. Chockalingam

    Abstract:

    MultiAntenna transmission using Load modulated arrays (LMAs) is gaining recent research interest. LMAs use a single central power amplifier and tune the Antenna Loads according to the information signal. In this paper, we propose a novel multiAntenna transmitter architecture that can enable high-rate transmissions using LMAs. The proposed architecture uses channel modulation with RF mirrors in conjunction with Antenna Load modulation to transmit information bits. The proposed architecture has two key advantages: 1) it facilitates simple construction of high-rate signal sets suited for LMAs, and 2) it requires significantly fewer channel coefficients to be estimated at the receiver compared to conventional channel modulation architectures. The proposed architecture is shown to achieve improved bit error performance compared to conventional Load modulation as well as spatial modulation, which are also single power amplifier transmission schemes. We also investigate the use of the proposed transmission scheme in a multiuser setting on the uplink. The proposed scheme not only offers the advantage of RF hardware simplicity at the user equipment but also requires fewer receive Antennas at the base station to achieve a target bit error performance.

  • Load Modulated Arrays Using Channel Modulation with RF Mirrors
    2019 IEEE 89th Vehicular Technology Conference (VTC2019-Spring), 2019
    Co-Authors: Sandeep Bhat, A. Chockalingam

    Abstract:

    MultiAntenna transmission using Load modulated arrays (LMAs) is gaining recent research interest. LMAs use a single central power amplifier and tune the Antenna Loads according to the information signal. In this paper, we propose a novel multiAntenna transmitter architecture that can enable high-rate transmissions using LMAs. The proposed architecture uses channel modulation with RF mirrors in conjunction with Antenna Load modulation to transmit information bits. The proposed architecture has two key advantages: 1) it facilitates simple construction of high-rate signal sets suited for LMAs, and 2) it requires significantly fewer channel coefficients to be estimated at the receiver compared to conventional channel modulation architectures. The proposed architecture is shown to achieve improved bit error performance compared to conventional Load modulation as well as spatial modulation, which are also single power amplifier transmission schemes. We also investigate the use of the proposed transmission scheme in a multiuser setting on the uplink. The proposed scheme not only offers the advantage of RF hardware simplicity at the user equipment but also requires fewer receive Antennas at the base station to achieve a target bit error performance.

  • LSE Precoder for Load Modulated Arrays with Channel Modulation
    IEEE Wireless Communications Letters, 1
    Co-Authors: Sandeep Bhat, A. Chockalingam

    Abstract:

    In this letter, we consider novel multiuser precoding techniques suited for Load modulated arrays (LMAs) on the downlink, wherein a base station employs an LMA to transmit data to multiple users. For implementation simplicity, it is desired that the Antenna Load impedance values in the LMA are drawn from a discrete set. For such LMAs with discrete-valued Load impedances, we propose an iterative precoding algorithm using the least square error (LSE) framework. For the same setting, we also propose a precoding scheme that employs channel modulation (CM) using radio frequency (RF) mirrors in each element of the LMA. This LMA-CM precoding scheme tunes the RF mirrors as well as Antenna Load modulators such that the instantaneous constraint of constant hypersphere signaling from a discrete set required for LMAs is satisfied. Improved distortion and bit error performance of the proposed schemes are reported.

S. Lindfors – 3rd expert on this subject based on the ideXlab platform

  • Behavioral level modeling of power amplifiers with varying Antenna Load
    2005 IEEE 61st Vehicular Technology Conference, 2005
    Co-Authors: T.s. Nielsen, S. Tawfik, T. Larsen, S. Lindfors

    Abstract:

    This paper presents an approach for behavioral level power amplifier modeling with varying Antenna Load. The derived model is based on device large signal S-parameter measurements of a commercially available W-CDMA power amplifier. A pulsed RF measurement setup, ensuring minimal device self-heating and providing variable complex Load impedance, is described in detail. The use of polar and Cartesian representation of the power amplifier Load impedance is discussed in terms of model complexity. The model validity is verified by comparing measured and simulate adjacent channel power ratios (ACPR). The measured and simulated ACPR show very good agreement and match at the nominal power amplifier drive level to within 2 dB over the maximum output VSWR ratings.

  • Fast predistorter adaptation to varying Antenna Load
    2004 IEEE 59th Vehicular Technology Conference. VTC 2004-Spring (IEEE Cat. No.04CH37514), 2004
    Co-Authors: T.s. Nielsen, S. Lindfors

    Abstract:

    The effect of varying power amplifier (PA) output VSWR is studied in a workfunction predistorter system. The resistive Load of a commercially available W-CDMA PA is tuned and the large-signal S-parameters measured. From the measurements, the optimum gain and phase predistortion functions are derived and studied. The predistorter coefficients are parameterized with a single variable that roughly fits optimum predistortion functions for other than nominal PA Loading conditions. The adaptation speed is evaluated in a complete predistorter system simulator and it is found that the number of iterations needed to adapt is reduced from 4 to 1.