Browsing by Author "Heino, Mikko"

Now showing 1 - 11 of 11
  • Thumbnail Image
    Item
    Design of a Reference Dipole-Loop Antenna Array at 28 GHz
    (2019-03-01) Miah, Md Suzan; Heino, Mikko; Icheln, Clemens; Haneda, Katsuyuki; Department of Electronics and Nanoengineering; Katsuyuki Haneda Group
    This paper proposes an array antenna at 28 GHz that can be used to measure polarimetric omni-directional pathloss. The array consists of a printed microstrip dipole and loop with an integrated tapered balun structure. The design and experimental results of low profile microstrip dipole and loop antenna show wideband matching and radiation performance. Over 6 GHz of -10 dB impedance matching bandwidth has been achieved for the dipole, whereas the loop shows 0.2 GHz ranging from 27.9 to 28.1 GHz. A fairly good agreement between the simulated and measured radiation pattern validates our simulation method. The omni-directional behaviors of both dipole and loop make it suitable as a reference antenna for over-the-air antenna testing at 28 GHz.
  • No Thumbnail Available
    Item
    Design of wavetraps for isolation improvement in compact in-band full-duplex relay antennas
    (2014-10-20) Heino, Mikko; Venkatasubramanian, Sathya; Sähkötekniikan korkeakoulu; Haneda, Katsuyuki
  • No Thumbnail Available
    Item
    Eksentrisyyden aiheuttaman voiman mittaaminen oikosulkukoneessa eri staattorikäämin kytkennöillä
    (2011) Heino, Mikko; Arkkio, Antero; Sähkötekniikan korkeakoulu; Turunen, Markus
  • Thumbnail Image
    Item
    Empirical Evaluation of a 28 GHz Antenna Array on a 5G Mobile Phone Using a Body Phantom
    (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2021-11-01) Vähä-Savo, Lauri; Cziezerski, Christian; Heino, Mikko; Haneda, Katsuyuki; Icheln, Clemens; Hazmi, Ali; Tian, Ruiyuan; Department of Electronics and Nanoengineering; Katsuyuki Haneda Group; Katsuyuki Haneda Group; Huawei Technologies
    Implementation of an antenna array on a 5G mobile phone chassis is crucial in ensuring the radio link quality, especially at the millimeter-waves. However, we generally lack the ability to design antennas under practical operational conditions involving body effects of a mobile user in a repeatable manner. We developed numerical and physical phantoms of a human body for evaluation of mobile handset antennas at 28 GHz. While the numerical human model retains a realistic and accurate body shape, our physical phantom has a much simpler hexagonal cross section to represent a body. Gains of the phased antenna array configuration on a mobile phone chassis, called colocated array is numerically and experimentally evaluated. The array is formed by placing two sets of 4-element dual-polarized patch antenna arrays, called two modules, at two locations of a mobile phone chassis. Modules are intended to collect the maximum amount of energy to the single transceiver chain. Spherical coverage of the realized gain by the array shows that the experimental statistics of the realized gains across entire solid angles agree with numerical simulations. We thereby demonstrate that our antenna evaluation method reproduces the reality and our phantom serves repeatable tests of antenna array prototypes at 28 GHz.
  • Thumbnail Image
    Item
    Isolation improvement and user-effect modeling for antenna arrays in 5G and beyond
    (Aalto University, 2020) Heino, Mikko; Icheln, Clemens, Dr., Aalto University, Finland; Elektroniikan ja nanotekniikan laitos; Department of Electronics and Nanoengineering; Sähkötekniikan korkeakoulu; School of Electrical Engineering; Haneda, Katsuyuki, Assoc. Prof., Aalto University, Department of Electronics and Nanoengineering, Finland
    The evolution of mobile phone systems has been fast in the past decades with 5G systems closely being deployed. This development of mobile networks requires new techniques to solve the ever-increasing demand for the number of users, even higher data rates, and the problem of spectrum scarcity. This dissertation describes several novel electromagnetic designs and modelling methods that enable 5G and beyond communication systems. In-band full-duplex (IBFD) communication utilizes the same frequency band for receiving and transmitting simultaneously. Thus, the spectral efficiency is doubled in the best case compared to current half-duplex systems. However, the major problem of IBFD is the strong self-interference (SI) between the transmitter and the receiver on the same device. To make IBFD communication feasible, in the first part of this thesis, electromagnetic wavetraps are proposed as a method to improve isolation between the receiving and transmitting antennas of a device. Wavetraps are resonant structures usually placed between antennas to decouple them. They suppress surface currents and scatter the transmitted electromagnetic fields suitably to cancel out the naturally coupled fields at the location of the receiving antenna, thus increasing the antenna isolation. Planar wavetraps are designed for a multiple-input-multiple-output (MIMO) IBFD relay where planar antennas are used. The methodology for designing and optimising wavetraps is established utilizing the theory of characteristic modes. The clear positive impact of the wavetraps on antenna isolation is experimentally verified both in the anechoic chamber and in realistic multipath environments. The effects of multipath environment on the obtainable isolation are characterized. The thesis furthermore introduces an antenna decoupling structure for bi-directional IBFD communications, where the isolation between omnidirectional collinear dipoles is significantly enhanced. Communication at millimetre-waves (mm-waves) is essential in future mobile communications due to wide available bandwidth that enables very high data rates. The second part of the thesis considers the effect of a human body to mm-wave handset antennas operating at 28 GHz and 60 GHz. The effect of the proximity of fingers to handset antennas is studied giving novel approaches how to mitigate the effect by utilizing beamsteering and by a thin reflector decreasing the shadowing over 20 dB. Furthermore, characterization of shadowing and scattering due to an entire human body is made possible at 60 GHz with a novel simulation model which reduces the computational complexity while keeping the modelling accuracy. Mm-wave base stations in urban areas need to be deployed densely in future communication systems to cope with expected severe link blockage. The third part of the thesis introduces a PCB-based beamsteerable end-fire antenna array at 28 GHz for low-cost base stations. The antenna array is integrated with a switch network and high gain antenna elements, obtaining high measured realized gain even with the high losses of PCB technology at 28 GHz.
  • Thumbnail Image
    Item
    Passive Antenna Systems Embedded into a Load Bearing Wall for Improved Radio Transparency
    (2021-01-12) Vaha-Savo, Lauri; Atienza, Alejandra Garrido; Cziezerski, Christian; Heino, Mikko; Haneda, Katsuyuki; Icheln, Clemens; Lu, Xiaoshu; Viljanen, Klaus; Department of Electronics and Nanoengineering; Department of Civil Engineering; Katsuyuki Haneda Group; Structures – Structural Engineering, Mechanics and Computation; Department of Electronics and Nanoengineering; Katsuyuki Haneda Group; University of Vaasa
    Providing cellular network services inside residential or office buildings has become challenging, especially for fifth-generation networks that use higher carrier frequencies. Additionally, new energy-efficient buildings contain envelopes such as low-emissivity glass and new multi-layer thermal insulations, all of which - unintendedly but effectively - also block radio signals. As a solution to those problems of indoor coverage, we suggest the use of passive antenna systems embedded into the building walls. We propose a numerical evaluation method for determining the electromagnetic transmission coefficient and the thermal insulation of a typical building wall. Next, we investigate two antenna configurations embedded to the wall, a two-patch and a four-patch design, both operating around 3.5 GHz. We show from numerical simulations that those antenna systems increase the transmission coefficient of the wall. At the same time, we show that the four-patch design does not compromise the thermal insulation of the wall.
  • Thumbnail Image
    Item
    Real-Time Demonstration of Antenna Effects on Emulated Wireless Capsule Endoscope Links
    (2020-03) Stasiunas, Rytis; Miah, Md Suzan; Heino, Mikko; Haneda, Katsuyuki; Icheln, Clemens; Department of Electronics and Nanoengineering; Katsuyuki Haneda Group; Aalto University
    A real-time over-the-air video transfer platform is developed for a wireless capsule endoscope scenario. With this platform, we aim at providing an intuitive and instant understanding of antenna effects on both quantitative and qualitative radio link performance, e.g., on video image quality, on bit error rate (BER) and on constellation diagrams of digital modulation. The platform consists of a host computer and a universal software-defined peripheral, complemented with an endoscope capsule mockup including an antenna, a liquid body phantom for creating a realistic inbody-to-onbody radio link scenario and an on-body antenna. The antennas operate at 433 MHz, while the liquid mimics the complex permittivity of colon tissue at that frequency range. Uncoded orthogonal frequency division multiplexing with 2.3 MHz bandwidth is adopted as a physical layer. Footage of the real-time demonstration is available from the link in [1] and shows the clear effects on radio link performance when 1) the distance of the capsule antenna from the wall of the liquid phantom is increased, and 2) when capsule antenna is moved out of the liquid phantom. In both cases, disruption of the video images is observed, due to an increased BER. The BER plots are reproduced in this paper as evidence. The demonstration has been used for post-graduate education to deepen students' understanding of the importance of antenna design, while the same benefit may be expected when showing the video to clinical experts who operate capsule endoscopes.
  • No Thumbnail Available
    Item
    Sähkömagneettisen säteilyn vaikutus ihmiseen tulevissa 5G-matkaviestinverkoissa
    (2019-05-21) Ojala, Vili; Heino, Mikko; Sähkötekniikan korkeakoulu; Turunen, Markus
  • Thumbnail Image
    Item
    Self-user shadowing effects of millimeter-wave mobile phone antennas in a browsing mode
    (2019-03-01) Heino, Mikko; Icheln, Clemens; Haneda, Katsuyuki; Department of Electronics and Nanoengineering; Katsuyuki Haneda Group
    In this paper a simulation method for estimating the shadowing effect of a human at millimeter-wave frequencies is presented. The shadowing effect is studied at 28 GHz and at 60 GHz for the case when a user holds a mobile phone. Both single-hand grip and two-hand grip browsing scenarios are studied with a dual-polarized mobile phone antenna. We use the integral equation method combined with a surface-impedance-based material model for the human. It is found that at 28 GHz the human body causes shadowing of up to 22 dB behind torso and head of the human, while at 60 GHz shadowing is up to 30 dB. On the other hand, in some other directions the human body effectively increases radiation by up to 5-10 dB through scattering and reflection. The novel method using a detailed human shadowing model is useful in evaluating mm-wave mobile terminal antenna performance in realistic multipath propagation environments.
  • Thumbnail Image
    Item
    Total array gains of millimeter-wave antennas on a mobile phone under practical conditions
    (2018) Haneda, Katsuyuki; Heino, Mikko; Järveläinen, Jan; Department of Electronics and Nanoengineering; Katsuyuki Haneda Group
    This paper studies a gain of an antenna array implemented on a mobile device operating at a millimeter-wave (mm-wave) radio frequency. Assuming that mobile phones at mm-wave range operate with a single baseband unit and analog beamforming like phased arrays, its total array gain comes from signal precoding or combining in excess to the omni-directional pathloss. The total array gain circumvents the ambiguity of conventional array gain which cannot be uniquely defined as there are multiple choices of a reference single-element antenna in an array. Two types of 8-element patch antenna arrays implemented on a mobile phone chassis, i.e., uniform linear array (ULA) and distributed array (DA) both operating at 60GHz, are studied. The gain is evaluated in a small-cell scenario in an airport shows that the DA achieves higher median gain by up to 8dB than the ULA when different orientations of the mobile phone are considered along with a body torso and a finger of a person operating the phone. There are always postures of the mobile phone where the ULA cannot see the line-of-sight due to directionality of the patch antenna on the mobile phone chassis and of body and finger shadowing, leading to outage array gain of -15dB. The DA has much smaller variation of the gain across different orientations of the phone, even when the human torso shadowing and user's finger effects are considered.
  • Thumbnail Image
    Item
    Total Array Gains of Polarized Millimeter-Wave Mobile Phone Antennas
    (2018-08-20) Haneda, Katsuyuki; Heino, Mikko; Jarvelainen, Jan; Department of Electronics and Nanoengineering; Katsuyuki Haneda Group
    This paper studies a gain of an antenna array implemented on a mobile device operating at a millimeter-wave radio frequency. Assuming that mobile phones at millimeterwave range operate with a single transceiver chain and analog beamforming like phased arrays, its total array gain is attributed to average gains of antenna elements and signal precoding or combining gains in excess to received power from a single-element dual-polarized omni-directional antenna. The total array gain circumvents the ambiguity of conventional array gain which cannot be uniquely defined as there are multiple choices of a reference single-element antenna in an array. Different polarized 8-element patch antenna arrays implemented on a mobile phone chassis, i.e., uniform linear array (ULA) and distributed array (DA) operating at 60 GHz, are studied. The antenna elements are placed so that they cover vertical, slanted or horizontal polarizations. The gain is evaluated for different orientations of the chassis along with effects of a body torso and a finger of a person operating the phone. The gain in a small-cell scenario shows that DA achieves higher gains than ULA regardless of polarization states of antenna elements at the base and mobile stations, and of the existence of line-of-sight in the links. Antenna polarizations do not make much impact on the total array gain as random orientation of a mobile phone and finger shadowing modifies the polarization states. The results show that antenna array geometry is more influential design aspect than polarization when a single transceiver chain is considered.